Change Log

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog and this project adheres to Semantic Versioning.

[Unreleased]

Language Support

General Features

Improvements

Fixes

[v7.0] - 2024-09-26

Language Support

Select expressions of packed arrays now always return an unsigned type, as mandated by the LRM
Clocking skew delays now properly require a constant value
Enforce that static methods can't have override specifiers
The error for invalid state-dependent path conditions in specify blocks can now be downgraded with -Wspecify-condition-expr for compatibility with other tools
Added support for the optional system tasks and functions from Annex D in the LRM: $countdrivers, $list, $input, $key, $nokey, $reset, $reset_count, $reset_value, $save, $incsave, $restart, $scope, $scale, $showscopes, $showvars, $sreadmemb, $sreadmemh, $getpattern
Added support for the optional compiler directives from Annex E in the LRM: `default_decay_time, `default_trireg_strength, `delay_mode_distributed, `delay_mode_path, `delay_mode_unit, `delay_mode_zero
Rules about nondegeneracy of sequences and properties are now enforced (thanks to @likeamahoney)
Special case rules about how name resolution works in bind directives are now enforced
Changed the definition of "simple types" to include string to allow using it as a target for assignment pattern fields (thanks to @likeamahoney)
Rules for inconsistent net types connected via an implicit named port connection are now enforced (thanks to @likeamahoney)

Clarifications in IEEE 1800-2023

Assertion clocking events can't reference automatic variables
The .* token sequence is actually two separate tokens that can be separated by whitespace
Functions in constraints cannot have inout arguments
Constraint subexpression can be of any type as long as their final expression type is numeric and they don't reference random variables
The argument to $isunbounded must be a parameter name (only enforced as a pedantic warning in slang)
Edge-sensitive paths in specify blocks can specify an edge keyword without also including a data source expression
Only bidirectional switches allow connections to nets with user-defined net types (other primitives do not)

New Features in IEEE 1800-2023

Constraint expressions and random variables can have real types
dist expressions can have a default specifier
dist expressions can have real types
solve-before constraints can specify array.size() as well as regular random variables
disable soft constraints can target array.size()
Constraint blocks can have override specifiers (initial / extends / final)
Covergroups can inherit from covergroups in parent classes
Coverpoints can have real types
Covergroups have new options: cross_retain_auto_bins and real_interval
New system functions $timeunit, $timeprecision, and $stacktrace

General Features

Added -Wunsigned-arith-shift which warns about suspicious arithmetic right shifts of unsigned types
Added -Wstatic-init-order and -Wstatic-init-value which warn about static initializers that depend on uninitialized values or an undefined order of other static initializers
Added -Wfloat-int-conv and -Wint-float-conv which warn about implicit conversions between floating point and integer types
Added -Wfloat-narrow and -Wfloat-widen which warn about implicit conversions between floating point types of differing widths
Added -Wunused-import and -Wunused-wildcard-import which warn about unused import directives
Added -Warith-op-mismatch, -Wbitwise-op-mismatch, -Wcomparison-mismatch, and -Wsign-compare which all warn about different cases of mismatched types in binary expressions
slang-netlist has experimental support for detecting combinatorial loops (thanks to @udif)
Added --allow-merging-ansi-ports (included in "vcs" compat mode) which allows non-standard behavior in which ANSI module ports can duplicate net and variables declared within the module
Added --ast-json-source-info which includes source line information when dumping an AST to JSON (thanks to @KennethDRoe)
Added --enable-legacy-protect which enables support for nonstandard / legacy protected envelopes: Verilog-XL style `protect directives and Verilog-A style // pragma protect comments

Improvements

Default value expressions for parameters that are overridden are now checked for basic correctness and other parameters they reference will not warn for being "unused"
Made several minor improvements to the locations reported for propagated type conversion warnings
Sped up Compilation object construction by reorganizing how system subroutines are created and registered
Improved the parser error reported when encountering an extraneous end delimiter in a member list
Various fixes and improvements were made to slang-netlist (thanks to @jameshanlon, @udif)
Added options to slang-tidy to better control what gets output (thanks to @Sustrak)
Added a bunch of new checks to slang-tidy (thanks to @JoelSole-Semidyn)
Improved handling of source files that contain non-UTF8 comments (thanks to @udif)
Fixed and improved various parts of the SyntaxRewriter API (thanks to @sgizler)

Fixes

Fixed several AST serialization methods (thanks to @tdp2110, @likeamahoney, @Kitaev2003, @cyuzuzo-j)
Fixed the return type of DPI import tasks
Fixed a bug that caused some inout ports to warn as "unused"
Fixed the checking of the extends override specifier when the containing class has no base class
Fixed a case where bracketed delay expressions in sequence concatenations were not checked for correctness
Fixed the type of the iterators used in with-expressions for covergroup bins
Fixed a bug that sometimes prevented printing the correct scope for type alias names in diagnostic messages
Fixed the hierarchical path string created for symbols inside of unnamed generate blocks (thanks to @povik)
Fixed spurious errors that could occur when using generic class instantiations inside uninstantiated generate blocks
Correctly disallow passing expressions of void type to format style system functions (thanks to @tdp2110)
Fixed a bug where parameters that referred to themselves via hierarchical reference would cause a crash instead of reporting a diagnostic
Fixed PATHPULSE$ specparam initializers to allow providing only one value instead of requiring two (thanks to @likeamahoney)
Fixed PLA tasks to accept concatenation expressions as arguments without reporting an error about the direction of the argument bounds (thanks to @likeamahoney)
Fixed a bug that could cause spurious errors in uninstantiated generic class definitions
Fixed the Symbol::getHierarchicalPath API to round-trip correctly
Fixed JSON serialization of integers to round-trip correctly
Fixed a bug in resolving defparam values inside of generate loops
Fixed checking of event arguments in system timing check functions
Fixed checking of deferred assertion function calls (thanks to @likeamahoney)
Correctly issue an error if a sequence or property has a formal argument with the same name as a local variable declaration (thanks to @likeamahoney)
Fixed a case of recursive property instantiation that was incorrectly disallowed (thanks to @likeamahoney)
Fixed bugs in checking for overlapping user-defined primitive table rows (thanks to @likeamahoney)
Fixed infinite loops in the parser when encountering constraint blocks with certain kinds of invalid tokens in them (thanks to @likeamahoney)
Fixed errors in assigning to select expressions involving members of virtual interfaces (thanks to @micron-ian)

[v6.0] - 2024-04-21

Language Support

Added --allow-bare-value-param-assigment (included in 'vcs' compat mode) to allow a non-standard module instantiation syntax where a single parameter value can be supplied without including parentheses
Added --allow-self-determined-stream-concat (included in 'vcs' compat mode) to allow the use of streaming concatenation expressions in self-determined contexts (instead of just in assignments)
Added --allow-multi-driven-locals (included in 'vcs' compat mode) to allow subroutine local variables to be driven by multiple always_ff / always_comb blocks
Added full support for SystemVerilog libraries and configurations
Added support for equality comparisons between virtual interfaces and actual interface instances (thanks to @likeamahoney)
Ref args are now correctly disallowed in fork-join_any and join_none blocks
Wildcard port connections now correctly avoid importing new symbols into a scope via wildcard imports
Added support for referencing interface instances in unpacked array concatenations involving virtual interface arrays

Clarifications in IEEE 1800-2023

Unsized integer literals can be any bit width, not just capped at 32 bits.
Unpacked unions are allowed as net types
Time literals should be scaled but not rounded to the current time precision
Multiline block comments are allowed in macro definitions
Set membership operations (case statements, inside operator) always allow unbounded literals
Unbounded literals can only be assigned to parameters with simple bit vector types
$cast arguments don't need to be singular at compile time
Checking for multi-driven variables in subroutines invoked from always_comb/_latch/_ff doesn't apply to tasks, only functions
Non-blocking assignments to elements of dynamic arrays are not allowed
Static casts are assignment-like contexts
Tagged union expressions must be primaries only (binary expressions are not allowed)
Severity system tasks should work in constant functions (and behave as elaboration-time tasks)

New Features in IEEE 1800-2023

Triple quoted (multiline) string literals
Macro stringification with triple quoted strings
Type parameters and the type() operator can now refer to incomplete forward typedefs
Type parameters can now specify a type restriction just like forward typedefs
The `timescale directive is disallowed inside design elements
Boolean expressions in conditional directives (ifdef, ifndef)
Function call expressions can be chained (slang already supported this but several issues related to it were fixed)
type(this) is now allowed in static contexts within class declarations
Soft packed unions
The index method of array iterators can be renamed via an argument to the method call
Unpacked arrays have a built-in map method
Classes can be declared final
Class constructor argument lists and extends argument lists can be declared default
Class methods can be declared initial, extends, and final
Added the weak_reference built-in class
Interface classes can be declared within other classes
The built-in process class is declared final
Value ranges gain new absolute / relative tolerance operators
ref static subroutine arguments

General Features

Added -Wmultibit-edge (on by default) to warn about clock edge triggers on multibit expressions
Added -Wint-bool-conv and -Wfloat-bool-conv to warn about multibit integer and floating point expressions used in a boolean context
Added -Wuseless-cast to warn about explicit casts to the same type as the underlying expression
Added -Wunknown-sys-name to allow downgrading the error that occurs when referencing an unknown system task or function
Added compilation unit listings to allow fine grained control over how sources are parsed into separate compilation units (including separating macro defines and include directories on a per-unit basis)
Added --defaultLibName to control the name of the default source library
Added --std to choose which version of the LRM slang should conform to. By default this is "1800-2017" but can be set to "1800-2023" to enable new features added in the recently published update to the SystemVerilog LRM.
Added a new experimental tool, slang-hier, that prints elaborated instances in a design (thanks to @udif)

Improvements

--cmd-ignore and --cmd-rename now also work with options that include a value via an equals expression
Information about module/interface/program definitions are now included in AST JSON output
slang-reflect has been improved to support reflecting more complex types for local parameters (thanks to @Sustrak)
Rewrote analysis of user-defined primitive tables to be much more efficient; previously primitives with large numbers of inputs could take a very long time to analyze
Command line defines now take precedence over defines in Verilog source files, which matches the behavior of other tools (thanks to @udif)
-Wvector-overflow has been improved to not warn when forming minimum negative integer literals
Backslashes at the end of lines in command files are now ignored instead of causing errors (thanks to @udif)

Fixes

Fixed several crashes in slang-tidy (thanks to @likeamahoney)
Fixed a bug where a missing `endif directive didn't always cause an error to be issued
Fixed the use of the this handle in non-static class property initializer expressions
Fixed a bug where use of the unqualified randomize would sometimes find std::randomize when it should have found a class-local randomize method
Fixed several spurious lexer errors when otherwise invalid tokens are used inside stringified macro expansion
Fixed a crash in the Python SyntaxVisitor bindings
Correctly allow instance paths to be used in assert control system function arguments
Fixed a bug where multi-driver checks for called subroutines didn't apply when one of the source procedures was a plain always block
Fixed bug in parsing empty action blocks for sequences and properties
Fixed the Python bindings for Type::isBitstreamType
Fixed a crash when calling getResolutionFunction on built-in net types
Fixed a bug in the checking of forward typedef type restrictions
Fixed the end spacing of stringified macro expansions
Fixed a macro expansion corner case where an escaped identifier that ends in a backslash was not considered as a line continuation for the macro body
Fixed several cases where invalid syntax could lead to follow on errors with malformed messages
Fixed several crashes related to corrupted source files containing embedded null characters or invalid UTF8 sequences
Fixed a crash that could occur when a source file ended in an invalid hex escape inside an unterminated string literal
Fixed an infinite loop when parsing a malformed list of terminals in a primitive declaration
Fixed an infinite loop caused by malformed recursive checker instantiations
Fixed an infinite loop when parsing case statements with malformed pattern items
Added checking for several missing invalid corner cases in user-defined primitive declarations
Fixed the propagation of unbounded literals through parameters used in expressions
Fixed handling of nested modules to be properly independent of each other when there are multiple instances of their parent module
Fixed handling of bind directives that target nested modules
Fixed handling of bind directives that appear in uninstantiated generate blocks
Fixed handling of include files that don't contain a newline character (thanks to @ihathbeer)
Fixed handling of classes that declare a member named "\new" with an escaped identifier
chandles are properly allowed in non-edge event expressions
Correctly disallow wait fork and expect in functions and final blocks
Fixed bug in computing bounds for assignments to slices of unpacked arrays
Fixed macro argument parsing when there are (* and *) tokens in them
Fixed a bug in SVInt::operator< when comparing the smallest possible negative integer (thanks to @Krym4s)
Correctly allow non-blocking assignments with a timing delay to be used in always_ff blocks (thanks to @udif)
Fixed checking of overlapping primitive table rows when the '-' output character is used (thanks to @udif)
Fixed checking for which kinds of functions are allowed in deferred assertion actions and sequence match items
Fixed a couple of places where range selects were not properly checked for overflow
Fixed sorting of diagnostics when buffers are loaded in non-deterministic order
Added error handling for packages that try to import themselves
Type references and assignments of type void are now correctly disallowed
Fixed several bugs in slang-netlist (thanks to @jameshanlon)
Fixed --allow-toplevel-iface-ports when used with interface arrays

[v5.0] - 2023-12-26

Language Support

Added support for specifying a modport when connecting an interface array port
Implicitly typed parameters that have range specifications are now considered assignment-like contexts (this behavior is not specified in the LRM but more intuitively matches user expectations)
Added support for using assignment patterns as lvalues (which finally finishes full support for assignment patterns)
Added partial support for SystemVerilog configurations. Support is incomplete and may be buggy.
Index selects after range/part selects are now disallowed, to conform to the LRM as well as match the behavior of other tools
An error is now issued for interface ports that connect hierarchically through a generate or instance array, as mandated by the LRM
An error is now issued for generic interface ports that are connected via a wildcard connection, as mandated by the LRM
Rules about where classes with private members are allowed to be used in bitstream casts are now enforced
Relaxed requirement that DPI import declarations have an explicit return type to match behavior of other tools
Added -Wdpi-pure-task to allow downgrading the error that DPI import tasks cannot be marked pure
Added --relax-string-conversions (included in "vcs" compat mode) to allow strings to implicitly convert to integers
Added --allow-recursive-implicit-call to allow implicit call expressions to be recursive function calls for compatibility with other tools

General Features

Minimum required compiler versions have been bumped to GCC 11, clang 16, and Xcode 15 (should be the last bump for a while)
Minimum required cmake version has been bumped to 3.20
Added --allow-toplevel-iface-ports to allow top level modules that have interface ports
Added -Wconstant-conversion which warns about conversions inside constant expressions that lose information
Added -Wsign-conversion which warns about implicit integral conversions that change sign
Added a -L option to control the default source library search order
The --diag-hierarchy option now takes a parameter of "always", "never", or "auto" to allow forcing or hiding instance paths in diagnostics

Improvements

Made several improvements to -Wimplicit-conv to make it less noisy
Cleaned up internal code related to wide character support for Windows. slang now relies on the relatively new utf-8 code page support in Windows; this does mean that Unicode paths will now only be handled correctly on or after Windows Version 1903 (May 2019 Update).
The maximum size of a type has been increased to 2^31 bytes (which matches VCS)
The --suppress-warnings feature has been optimized to not perform unnecessary filesystem operations

Fixes

Fixed a case where -Wimplicit-conv would not be issued for mismatching struct types
Fixed a crash when $static_assert condition is parenthesized
Fixed the count of compilation errors reported when using -Werror along with --suppress-warnings
Fixed -Wvector-overflow to work correctly with signed literals
Fixed the type infered for parameters that are assigned vector literals larger than 32-bits wide
SystemVerilog class types (and other types that contain them) are now limited to the max object size supported by slang (the same limit for structs and arrays that was already present)
Fixed a few places where large types or expressions could result in internal overflow of variables tracking their sizes, which could cause crashes or other strange behavior. Now a proper error is issued.
A proper error is now issued for duplicate local variables inside of properties and sequences
Fixed a crash when trying to connect an extern subroutine implementation to an interface array port
Fixed a spurious error about signals being multi-driven from uninstantiated generate blocks
Fixed a spurious error when streaming concatenations are used in port connections of uninstantiated modules
An appropriate parse error is now issued for generate blocks that are missing a body
Fixed a crash when classes with cycles in their members are used in a cast expression
Fixed a bug in parsing parameter ports when their type was explicitly package scoped and the parameter keyword was elided
Fixed a bug in the slang driver that prevented showing instance paths in diagnostics
An error is now issued for invalid use of the unique and priority keywords in else blocks

[v4.0] - 2023-08-10

Language Support

Finished full support for user-defined primitives by adding error checking for table entries
Support for whitespace between the two characters of the dist weight operators has been added for compatibility with other tools -- this is an error by default but can be downgraded as needed. See -Wsplit-distweight-op.
Added support for net aliases
Added support for checkers
Added support for extern modules/interfaces/programs/primitives, along with wildcard port lists in declaration headers

General Features

slang now requires a C++20 compatible compiler to build (e.g. minimum GCC 10)
New warnings -Wport-width-expand and -Wport-width-trunc separate out width warnings that occur in port connections from general expressions elsewhere. This makes it easier to find and target these specific cases of width mismatches.
New option --suppress-macro-warnings that functions similarly to --suppress-warnings except that it applies to the original definition location of macros instead of their expansion location. This is useful if, for example, you want to hide warnings from 3rd party macros (like from UVM) that you use in your own code.
A new experimental tool called slang-netlist has been added (thanks to @jameshanlon) -- see the readme for more details
A new experimental tool called slang-reflect has been added (thanks to @Sustrak) -- see the readme for more details
The slang build optionally supports obtaining dependencies via conan.io -- see the docs for details.
The slang driver now accepts file patterns to make it easier to select groups of files
Initial support for source libraries and library map files has been added. This is only for specifying input files right now but in future releases will be expanded to work with SystemVerilog config declarations.

Improvements

When dealing with duplicate module/interface/program definitions (where the error has been downgraded to a warning) slang will now make use of the first definition seen instead of any later ones, to better match the behavior of other tools
Improved the warnings issued for unused 'inout' ports
Macros declared in slang headers have been namespaced to avoid polluting user code
Several hash table implementations used by slang (ska::flat_hash_map, unordered_dense, StringTable) have been removed and consolidated into using boost::unordered. The library includes a minimal boost_unordered.hpp header to avoid needing to depend on all of boost.
Added a dependency on the mimalloc custom allocator (can be disabled if desired)
A number of small optimizations (including the switch to boost::unordered and use of mimalloc) combine to improve general slang compilation performance by about 10%
slang can now build correctly with exceptions and RTTI disabled, to allow integration with other codebases that disable use of these features
The slang driver will now parse input files in multiple threads by default. This can be disabled with --threads=1. This feature is not supported when using --single-unit.
The --libdir feature will now search for files based on interface port declarations in addition to module instantiations (thanks to @AndrewNolte)
Support for visitors has been added to the Python bindings (thanks to @tdp2110)
Low-level file loading routines in slang have been rewritten to use platform-level APIs. This should slightly improve performance, but more importantly it allows slang to report system-specific error messages when file loading fails.
Failed file loads invoked via the Python bindings now raise an appropriate Python exception
The --suppress-warnings option has been changed to take a file pattern instead of a directory path prefix. Existing uses of this flag will need to be updated to the new behavior.
Most command line arguments that accept multiple values now accept those values as a comma-separated list in addition to repeating the argument multiple times
slang can now read input from stdin by specifying a file named '-'

Fixes

Fixed a bug that prevented indexing into an interface array when accessing that array hierarchically
break and continue statements are now correctly disallowed from controlling a loop outside of a fork-join block
Duplicate driver checking now applies to signals accessed via modports
Subroutine ports with initializers will now issue an appropriate error
Subroutine argument default values are now checked for the correct direction and count as drivers for target symbols
Fixed messaging generated by elaboration system tasks when arguments are invalid
Fixed an off-by-one error in symbol lookup location for detecting whether parameters are used before they are declared
Fixed a few return value policies in the Python bindings that were incorrect
Fixed a bug where a continuous assign statement that referenced an implicit net more than once would cause an error about duplicate net declarations
Fixed the use of the $global_clocking system functions in direct event controls
Fixed an erroneous diagnostic when checking which kinds of expressions are allowed in a binary and or or property expression
Fixed parsing of tagged patterns when followed immediately by a &&& predicate
Added tests and fixed resulting issues found in AST serialization and visitation methods
The Compilation constructor now ensures it safely only adds type diagnostic printing callbacks once, to allow multithreaded use of separate Compilation objects
Fixed the error message reported for -Wimplicit-port-type-mismatch -- it was reporting the wrong types involved
Fixed parsing of parameter ports that have multiple declarators -- previously later parameters in the list were not being associated with the prior type declaration

[v3.0] - 2023-03-18

Highlights

As of this release slang passes 100% of the tests at https://github.com/chipsalliance/sv-tests (the only tool able to do so).

Language Support

Added support for specify module timing paths
Added support for specify pulsestyle and showcancelled directives
Added support for PATHPULSE$ specparams
Added support for system timing checks
Added support for program namespacing rules
Added support for anonymous programs
Added support for DPI open array typed arguments
Added support for $inferred_clock and $inferred_disable
Finished full support for bind directives
Finished full support for defparams

General Features

New option --obfuscate-ids when used with --preprocess will replace all identifiers in the output with obfuscated alphanumeric strings (thanks to @Sustrak)
Added a group of new warnings to report on unused code elements; see -Wunused
A new (currently experimental) tool, slang-tidy, has been added as a place to collect more in-depth or project-specific static analysis rules (thanks to @Sustrak).
New option --suppress-warnings allows suppressing warnings from one or more file paths, intended to allow easily hiding warnings from 3rd party code

Improvements

The default library name for slang has been changed to "libsvlang" to avoid clashing with an existing "S-lang" package on most Linux systems. The library name is now configureable via CMake.
Errors about unknown package names are now ignored in lint-only mode
Drastically improved the performance of overlapping driver checking and driver loop unrolling. For large projects this may reduce compile times by as much as 80-90%.
Net charge strength and drive strength have been added to the AST
Added human-friendly names for function arguments in Python bindings (thanks to @Kuree)
Conditional statements in constant functions now implement unique/priority semantics (thanks to @HungMingWu)
Procedural force/release of bit selects or part selects is an error according to the LRM; this error can now be downgraded to a warning for compatibility with other tools (thanks to @udif)
Implicit named port connections with inequivalent types are disallowed by the LRM; this error can now be downgraded to a warning for compatibility with other tools
When printing type names in diagnostics, if more than one type shares the same simple name, they will now be disambiguated with their full path
A new --timescale option allows setting a default time scale for design elements. If this option is not set, there is no default and an error will be issued if not all elements have a time scale specified (as required by the LRM).

Fixes

Parameters used inside specify blocks will now issue an appropriate warning
Fixed an issue where the parser erroneously allowed selects of integer literal expressions
Top-level programs are now automatically instantiated, just like top-level modules
Implicit covergroups declared inside classes were previously not being checked for correctness
Fixed parser handling of spacing within always@( *) statements being misinterpreted as a closing attribute token (thanks to @godblesszhouzhou)
Fixed a bug in the lookup location used for non-ansi port symbol attribute expressions
Fixed -Werror to actually work
Tweaked handling of unbased unsized literals to reduce false-positive width warnings
Changed scoped access to incomplete forward typedefs to be allowed as long as the final name in the chain is not a type (matches behavior of other tools)
The parser now correctly disallows attributes on assignment operators
References to compilation unit items from within packages is now correctly disallowed
Hierarchical references from packages to items outside that package are now correctly disallowed
Bit-vector system functions (such as $countbits) can now be used with bitstream types (as opposed to just integral types)
Max size limits for packed and unpacked arrays and structs are now strictly enforced
Invalid inferred time scales will now issue an appropriate error
Fixed a bug in arithmetic of large constants at compile time (thanks to @adream307)

[v2.0] - 2022-10-29

Highlights

This release focuses on making slang much more usable as a library. There's been a large amount of refactoring and reorganizing to make usage more straightforward. The CMake build was rewritten, and documentation showing how to integrate the library has been improved. Python bindings have been added to make it easy to use slang in scripts and tools.

Language Support

Added support for modport port expressions
Added support for modport exports and extern interface methods (including the rules for extern forkjoin methods)
Directionality of modport ports is now enforced (e.g. assigning to an input modport port is now an error)
Added full support for SystemVerilog's pattern matching feature, including usage in constant expressions
Added parsing support for config declarations
The parser now enforces syntax rules around specify block edge descriptors
Port connection slicing across arrays of instances is now also allowed with implicit port connections
Access to static class data members via an incomplete forward typedef is now allowed
Compile-time constant out-of-bounds element and range selects have always been an error in slang. The LRM allows for them to either be an error or optionally to result in 'x and compilation to continue -- to support this option the resulting errors have been changed to suppressible warnings (though still set to errors by default).
`pragma protect directives are now validated for correctness and encoded text is now decoded by slang (in all four decoding formats mentioned by the LRM). Actual encrypted text is not decrypted but just skipped instead -- it's very unlikely any IP vendor will ever provide slang with a decryption key so there's little point in implementing it.
Duplicate module / interface / program / primitive definitions have been made a suppressible error to support legacy workflows (thanks to @udif)

General Features

New warning: -Wempty-body (on by default) warns about likely accidental usage of semicolons after a loop or if condition that causes the body to be empty
New warning: -Wreversed-range (on by default) warns about a reversed open range that will behave as if it's an empty set instead
Added Python bindings for the library
Driver code has been factored out of the slang-driver tool into a Driver class that can be consumed by users of the library that are creating their own frontend tools
slang now treats all input source files as being UTF-8 encoded. Previously slang required all sources to be ASCII encoded but did not strictly enforce that, and could behave incorrectly when encountering non-ASCII characters. Now all characters are validated and UTF-8 sequences are handled correctly (and are allowed without issue inside string literals and code comments). Invalid UTF-8 sequences are diagnosed and a warning will be issued.
The default set of warnings was tweaked - some were added and some removed. See the Warning Reference for more information about which are on by default.
The --libraries-inherit-macros flag was added to allow macros defined in primary source files to bleed over into automatically loaded library files. The --single-unit option must also be used when providing this option.
New options --cmd-ignore and --cmd-rename can be used when you have existing command files with option flags designed for another tool to process (thanks to @udif)
New option --ignore-directive can be used to ignore vendor-specific preprocessor directives that would otherwise cause slang to flag an error (thanks to @udif)
Added --time-trace to profile where slang is spending its compilation time

Improvements

slang now reports a better error when you forget to put parenthesis after a module or interface instantiation
Lots of internal code cleanup, static analysis and lint fixes, and cleanup of TODOs in this release
Large integers printed in diagnostics will now be abbreviated to avoid filling the console with tons of digits
Added a limit to the size of instance arrays, to avoid hangs and running out of memory when typos produce huge array sizes. Use --max-instance-array if you run into the limit in a real design.
Made several improvements to parser error recovery to cover common coding errors
Several improvements were made to the SyntaxVisitor and SyntaxRewriter helper classes (thanks to @HungMingWu)
Many improvements were made to the cmake build and installation flow. slang should be much more easily consumed as a library in downstream projects.
Wrote more documentation and improved the doc build and its presentation
A lot of code was reorganized internally into more easily discovered locations. Library code is now organized into namespaces.
slang should now build correctly as a shared library out of the box
Made several minor optimizations across the library that should add up to about 10-15% compilation speed improvement for typical workflows
The minimum compiler version for slang was bumped to GCC 9. This will move to GCC 10 (and allow use of C++20 features) after the next release.

Fixes

Fixed ICE when a subroutine declaration refers to itself in its own return type declaration
Fixed several issues with Unicode path handling on Windows
Fixed a parser bug where a colon followed immediately by a line comment would be parsed incorrectly (thanks to @HungMingWu)
Fixed a parsing bug with restrict property statements
Fixed several crashes and internal assertions in corner cases discovered by fuzz testing
Fixed a number of cases where a proper diagnostic in an error scenario would be followed by one or more spurious diagnostics -- now only the one proper diagnostic is issued
Fixed a number of cases where a diagnostic with a formatted message might put an empty string into that message, which was confusing and not helpful
Constraint blocks are now correctly disallowed outside of class declarations
The $bits system function can now correctly reference automatic variables from static initializers
Fixed struct member declarations that referred to other members in the same struct type as part of their type declaration
Fixed handling of defparams when there are infinitely recursive modules in the design
The macro list printed by --macros-only is now sorted for consistent ordering between runs
Fixed a bug where diagnostic pragmas were not correctly handled when found in automatically loaded library source files
Source files listed in command files are now processed strictly in order relative to files listed in other command files, which gives predictable behavior when treating them as a single unit
The check for maximum include stack depth was erroneously including all files in its count when using single-unit builds
Fixed a bug that could cause case statements in constant expression to be misevaluated under certain conditions
Fixed the inferred type of untyped parameters when initialized from an equivalent but not matching type expression
Fixed a bug in the parser that could misparse delayed statements after an event control expression

[v1.0] - 2022-06-25

Highlights

slang can now detect and enforce all of the various rules surrounding multiple drivers on nets, variables, and ports. This release also comes with support for functional coverage constructs, opt-in support for hierarchical names used within constant expressions, and some additional compatibility functionality to make it easier to use with codebases that primarily build with other, less-conformant tools.

As of this release, no pre-built binaries will be included. They were of limited usefulness and difficult to maintain and so it's not worth providing them -- build from the source release instead.

Language Support

Added full support for covergroups, cover points, cover crosses, coverage bins and options.
Added support for untyped mailboxes.
Hierarchical references can now be used in constant expressions by passing the --allow-hierarchical-const flag. This is not strictly legal in SystemVerilog but other tools allow it and so slang supports it for compatibility.
Added support for non-ansi interface ports.
Added support for user-defined nettypes in module and interface port lists.
Added support for non-ansi "multiports" and sliced ports.
Added support for explicit ansi and non-ansi ports.
Added support for generic interface ports.
Added support for nested module and interface declarations.
Added the LRM rules for port collapsing of dissimilar net types.
Added rules around multiple drivers or mixed continuous and procedural drivers for variables and uwires.
Added rules for port connection directions (input vs output).
Added rules to disallow reading output clock variables or continuous assignments to the target of a clock variable.
Added rules to disallow assertion local variables from being driven by more than one output local variable formal argument.
Added rules about what timing controls are allowed in always_comb / always_latch / always_ff.
Added rules for user-defined nettype resolution functions.
Added LRM-specified warnings when net port coercion occurs.
Added full support for interconnect nets.
Added support for let declarations and nettypes inside of statement blocks.

General Features

A missing include directory passed to the driver tool is now a warning instead of an error.
A --compat flag was added to allow specifying general compatibility requirements with other tools. Currently only vcs is supported as a value. This enables a bunch of other flags to try to be compatible with VCS as much as possible.
+incdir and +define flags were added to increase compatibility with other tools.
Support for "command files" was added -- use the -F and -f flags to specify the path to a command file. Command files allow more conveniently specifying large lists of files and command line options to an invocation of the tool. See Command Files for more detail.
Added a $static_assert elaboration task that takes a condition and fails compilation if that condition is false. See Nonstandard Built-In Functions for an example.
Added a --relax-enum-conversions flag to do less strict type checking of enum conversions, for compatibility with other tools.
Integer literal overflow is now a warning instead of an error.
All warning flags are now documented with examples here: Warning Reference
The -Wno-top warning flag was renamed to -Wmissing-top to avoid confusion with the -no prefix.
Added a --allow-dup-initial-drivers flag which allows duplicate drivers from initial blocks instead of causing an error, for compatibility with other tools.
By default, procedural for loops will be unrolled if possible before checking for duplicate driver errors. The LRM is actually more strict and does not allow this looser form of driver checking, so a --strict-driver-checking flag has been added to disable it. More details at Driver Loop Unrolling.

Fixes

A better error is reported when trying to hierarchically refer to a type name.
$unit based names are no longer erroneously considered hierarchical.
The coverage system functions now allow a standalone $root as an argument.
Finished a bunch of TODOs and corner case handling in port declarations.
Made several tweaks to the parser's error recovery to get better diagnostics for commonly made mistakes.
Fixed issues with non-ansi port declarations that used named types.
Port initializers are now correctly required to be constants.
The $dumpvars function is now allowed to dump nets as well.
Fixed ICE when exporting an imported enum member from a package.
Fixed the printing of hierarchical path names in diagnostics.
Fixed macro stringification of substituted string literals.
Parameters with unpacked dimensions are now allowed to have a partially inferred type (with a logic base element type).
Report an error for variables connected to inout ports.
Report an error for unconnected ref ports.
Top-level modules cannot have ref ports.
Fixed JSON serialization of method prototype arguments.
A better error is reported when trying to assign to a constant.
Correctly disallow inout uwire ports.
Fixed how subroutine argument types are inferred if not explicitly provided.
Fixed a bug that allowed some errors in class randomize lookups to go unreported.
Fixed a double reporting of errors when enums have an invalid base type.
Fixed selection of enum values that are members of a struct declaration.
Fixed type compatibility checking for types that share the same source syntax but live in different logical places in the hierarchy.
Report an error if there are cycles in a class inheritance chain.
Fixed the threshold for unrecoverable lexer errors to not include warnings in the count.
Fixed some corner cases where lvalues of system methods were not properly validated.
Correctly error if there are duplicate out-of-block class method definitions.
Correctly require for loop variable declarations to have initializers.
Fixed a few parsing corner cases for user-defined primitives.
Correctly disallow assertion local variables from being referenced in event expressions.
Fixed an incorrect implicit conversion of string literals inside of concatenation expressions.

[v0.9] - 2022-01-06

Highlights

This release focused on fixing bugs, improving compatibility with other tools, and internal code cleanup. There were still some good language additions though, such as let expressions and randsequence statements.

Language Support

Added the built-in coverage control methods and predefined macros (thanks @jrudess)
Added the PLA system tasks (thanks @jrudess)
Added support for let declarations and let expressions
Added support for package export directives
Added full support for union data types, including packed / unpacked / packed tagged / unpacked tagged variants
Added support for randcase statements
Added support for randsequence statements
Added more support for assignment patterns and cleaned up various corner cases and error handling issues. The only thing still not supported for assignment patterns is when they are used as an lvalue.
Added support for $psprintf as a non-standard alias for $sformatf for compatibility with other tools
Allow macros to be named after keywords for compatibility with other tools
Added support for extended foreach array name syntax for compatibility with other tools. For example:

int array[2][2];
foreach (array[i]) begin
    foreach (array[i][j]) begin
        array[i][j] = (i + 1) * (j + 1);
    end
end

Allow macro argument substitution inside of escaped identifiers for compatibility with other tools
Allow macro expanded arguments to insert line continuations when used inside another define directive for compatibility with other tools
Added support for clocking blocks in modports
Added support for accessing clocking blocks through virtual interfaces
Changed rand_mode and constraint_mode to always be considered functions for compatibility with other tools
Specifying a lifetime on a method prototype has been changed from an error to a warning, to make life easier for legacy codebases

General Features

The minimum required cmake version has been bumped to 3.15
Added a warning for non-blocking assignments used in final blocks (thanks @jrudess)
Made some general improvements to the SyntaxRewriter APIs
Instance caching was removed and parameter evaluation was reworked to better support hierarchical names in parameter values in the future. This is not allowed in SystemVerilog but some tools allow it anyway, so this sets the groundwork for eventually supporting it in slang as well.

Fixes

Fixed some spurious errors inside of foreach loops within uninstantiated modules
Fixed error reporting when an invalid base type is used for an enum
Fixed error reporting when an invalid net initializer is used in a package
Fixed the check for tasks being called from a constant expression
Fixed a crash when specparams are given an invalid data type
Fixed the error message issued when dynamic array range selection bounds are reversed
Fixed a crash within the handling of unbounded literals being assigned to parameters
Correctly prevent self-referential parameter initializers
Correctly allow property and sequence expressions in instance port connections
Fixed various bugs in parsing covergroups
Fixed an issue that could cause array iterator methods to evaluate to the wrong value in constant expressions
Correctly allow event trigger and wait_order statements to target an element of an array of events
Fixed class member accessibility checking from within randomize inline constraint blocks
Fixed type checking for unpacked arrays of strings in set membership expressions
Fixed overriding of inherited enumerands in extended classes
Fixed class member accessibility checking from out-of-block method default argument expressions
Fixed parsing of virtual interface properties with class qualifiers
Added class definitions to JSON AST output
Fixed a parsing ambiguity in parenthesized event expressions
Fixed an assertion when macro stringifying an escaped identifier
Fixed dist constraint type checking
Fixed implicit macro concatenation with adjacent tokens
Correctly allow scope randomize arguments to be considered rand variables
Fixed a bug in SVInt::operator< where both sides are 0 with large bit widths
Fixed an assertion when data type expressions have erroneous invocation syntax
Fixed a sequence repetition parsing bug
Fixed lookup resolving through typedefs that point to an error type
Fixed binding of special methods on dynamic array (and other) types
Fixed crash on default value checking for empty assignment patterns
Fixed checking of allowed types in constraint expressions
Fixed spurious errors in virtual interface assignment checking
Correctly disallow out-of-block class methods from having static variable lifetime
Fixed $sformat argument checking
Fixed class inheritance issues caused by circular references in base class constructor calls
Fixed spurious errors in uninstantiated generic classes with unknown base classes
Improved error reporting for invalid uses of dist expressions
Correctly handle nested chains of invocable symbols after lookup
Fixed an off-by-one error in lexer's splitTokens method that led to misparsing some literals
Fixed a crash when speculatively evaluating an assignment to an expression type that doesn't implement evalLValue
Fixed various places that could silently fail during constant evaluation
Fixed an issue where upward names could fail to properly issue all related diagnostics
Fixed evaluation of body parameters with defaults that depend on local functions

Extra Thanks

@Kuree for some build fixes and adding macos to the CI build
@jesec for some patches to fix the build on non-x86_64 platforms
@eggman79 for reporting and providing a patch for a memory leak
@jrudess for reporting many issues and providing helpful test cases
@chengniansun for running fuzz testing and reporting a bunch of discovered crashes

[v0.8] - 2021-08-14

Highlights

Support was added for concurrent assertions, including sequences, properties, and clocking blocks.

Language Support

Support for declaring sequences, including all sequence expressions
Support for declaring properties, including all property expressions
Support for all concurrent assertion statements
Initial support for parsing checker declarations
Support for #1step delay values
Support for clocking blocks and clocking variables
Support for default and global clocking blocks
Support for cycle delays
Support for synchronous drives
Added the $global_clock system function
Added the global clocking sampled value system functions
Support for default disable declarations
Support for slicing arrays of instances in hierarchical selections
Initial parsing support for net aliases
Initial parsing support for package exports
Initial parsing support for randsequence statements
Support for assigning unbounded literals to parameters
Added the $isunbounded system function

General Features

Added a specialized diagnostic for when wire is misused as a data type
Added a set of CLI options to control the format of printed diagnostics, such as whether they include line numbers, column numbers, source snippets, etc.
Added a --allow-use-before-declare flag which suppresses errors about names being referenced before their declarations, to ease compatibility with less compliant tools
--libdir will now search for missing packages in addition to missing modules

Fixes

Fixed many parsing issues related to assertion expressions
Fixed the printing of type aliases in diagnostics when they point to virtual interfaces
Fixed type compatibility checking for virtual interfaces
Fixed issues with parsing let declarations
Fixed a bug where predefined integer types that had a signed qualifier added would no longer be treated as a predefined type
Fixed interconnect net parsing
Fixes for covergroup parsing
Fixed a bug related to assigning lookup indices to generate blocks
Correctly enforce rules about the contents of deferred assertion action blocks
Correctly disallow system functions with output arguments from being used in invalid contexts
Fixed the elaboration system tasks to correctly check for constant evaluation errors

[v0.7] - 2021-04-02

Highlights

slang now supports enough features to elaborate UVM tests.

Language Support

Finished support for upward name lookup
Support for $ in queue expressions
Max bound constraints for queues are now enforced at compile time in constant expressions
Support for the %l and %v format specifiers
Support for the parameterized std::mailbox class (the dynamic unparameterized form is not yet supported)
Partial support for virtual interface variables and expressions
Finished implementing rules for procedural continuous assignments
The preprocessor now supports concatenating together block comments at macro expansion time, which allows code like this to work:

`define FFSR(__q, __d, __reset_value, __clk, __reset_clk) \
  `ifndef FOOBAR                                          \
  /``* synopsys sync_set_reset `"__reset_clk`" *``/       \
    `endif                                                \
  always_ff @(posedge (__clk)) begin                      \
    __q <= (__reset_clk) ? (__reset_value) : (__d);       \
  end
module m;
  logic q, d, clk, rst;
  `FFSR(q, d, 0, clk, rst)
endmodule

Support for the stochastic analysis system tasks and functions
Support for the probabilistic distribution system functions
Support for the $sdf_annotate system task
Partial support for defparams (does not yet support instance arrays or specific rules about interfaces)
Support for specparams
Support for user-defined primitives and instances
Added parsing support for specify blocks, path declarations, and system timing checks
Finished support for built-in gate primitives, including type checking of ports and delay expressions
Finished implementing rules about which kinds of statements and expressions are allowed in function bodies
Finished implementing rules about which kinds of expressions can reference automatic variables
Support for null non-ansi module ports
Finished support for type reference expressions

General Features

Added a --lint-only flag that does not try to find top-level modules and skips errors related to unknown module instantiations
Added -Wformat-multibit-strength as a pedantic warning when using %v with multibit nets
Added -Wenum-range when enum element ranges are not integer literals (as opposed to some constant expression instead)

Fixes

randc variables are now correctly disallowed in soft constraints
static constraint blocks are allowed to access instance members
Fixed detection of whether colors are supported in the calling terminal from the driver
Reals and strings are now correctly converted to integers when passed as integer display format arguments
Various rules for continuous assignment lvalues are now correctly enforced
Delay values specified in continuous assignments are now checked for correctness
Fixed parsing of function-like macros that have escaped names
Fixed a bug that allowed multiple unary prefix operators to be placed next to each other in an expression
Fixed an overly restrictive check on literals that are allowed in enum initializers
Correctly disallow return statements in fork-join blocks
Fixed a bug that incorrectly propagated signedness to the rhs of assignment operators
Fixed a bug that failed to slice connections to output ports across instance arrays
ref arguments are now correctly disallowed in static subroutines
Fixed expression lookup locations for non-ansi ports that have split I/O declarations and initializer expressions
Allow real-to-integer conversions by default in repeat statements, $readmem and $writemem tasks
Fixed a bug that normalized away negative packed array bounds
Correctly disallow items in generate blocks based on the parent definition kind
Correctly disallow instances of modules, interfaces, and programs based on the context in which they are instantiated
Fixed overly permissive parsing rules for package headers
Correctly allow non-blocking assignments to class properties
Correctly disallow net initializers in packages
Fixed default lifetime determination for packages and procedural blocks

[v0.6] - 2021-01-10

Highlights

Many large open source SystemVerilog codebases can now be fully elaborated by slang, such as the black-parrot project.

Language Support

Partial support for bind directives
Support for modports, including enforcing all connection and port access rules
Full support for DPI import and export directives (except for open array arguments)
Support for the $assertcontrol family of system tasks
Support for iff conditional event controls
Support for wait statements
Support for procedural assign / deassign / force / release statements
Support for intra-assignment repeat event controls
Implemented remaining support and rules for nets, net types, net delays, and user-defined net types
Support for ref arguments
Support for all built-in methods on associative arrays
Support for the built-in std package
Support for the std::process class
Support for the std::semaphore class
Enforce all rules around optional parenthesis when invoking subroutines
Support for with array iterator expressions, including in constant expressions
Added the sum, product, sort, rsort, reverse, shuffle, min, max, unique, unique_index built-in array methods
Added the find, find_index, find_first, find_first_index, find_last, find_last_index built-in array methods
Support for rand and randc class properties
Added the randomize, pre_randomize, post_randomize, srandom, get_randstate, set_randstate built-in class methods
Added the $urandom_range system function
Added the rand_mode and constraint_mode built-in methods on classes and properties
Full support for class constraint declarations and constraint blocks, including all class qualifiers and name lookup rules
Full support for inline constraint blocks via with expressions on randomize calls, including local:: name lookup
Support for left justifying integers when formatting with $sformatf

General Features

Added a -G command line option which can override top-level module parameter values
Added a --ast-json-scope option which controls which scopes are dumped to JSON
Added -Wwidth-expand and -Wwidth-trunc (both off by default) which warn about implicit integral conversions that change size
Added -Wimplicit-conv (on by default) which warns about implicit conversions between different structs / unions / enums
Did a cleanup pass on warning text and grouping into categories. The default set of warnings should now consist only of warnings that have a very high likelihood of being a real problem. The -Wextra group is recommended but not enabled by default. -Wconversion is a new group that includes all implicit conversion-related warnings.
Added a --ignore-unknown-modules flag which suppresses errors for instantiations of unknown modules
The driver tool now prints errors to stderr instead of stdout
Added --libdir and --libext flags to allow automatically searching for files to include in the build when encountering unknown modules
Added a -v flag to include source files that are treated as "libraries", meaning modules in them are not automatically instantiated

Fixes

Fixed many issues related to spurious semantic errors reported inside uninstantiated modules
Fixed traversal of statement bodies via the ASTVisitor helper class
Fixed incorrect errors reported for non-ANSI ports with separate I/O and type declarations
Fixed many issues related to method prototype declarations
Unpacked arrays now correctly support up to 2^31 elements
Implicitly typed parameters that are assigned string literals are themselves treated as string literals in other expressions
Fixed accidental truncation of bits that was occurring when connecting array ports across interface instance array instantiations
Fixed type checking for compound assignment operators
Fixed lookup of class names in packages
Fixed many issues with class inheritance
Fixed crash when visiting generic class specializations leads to more specializations being created
Fixed merging of port types across separate I/O and type declarations, including in subroutine bodies
Fixed foreach loops to work with strings and predefined integer types
Fixed foreach loops over class properties
Don't report an error when void casting a system subroutine that can be both a task and a function
Fixed a check for variable initializers that reference themselves in their own declaration
Fixed lookup of subroutines when invoking them without parenthesis
Port connections were missing in AST JSON output
Fixed lookup of event objects in various statements
Fixed visibility checks for members of generic classes
Trailing '%' symbols in format strings are now a warning instead of an error

[v0.5] - 2020-10-26

Highlights

This release contains full elaboration support for classes, including generic classes, virtual classes, and interface classes.

Language Support

Added full support for classes and all related features
Added support for bitstream casting (thanks to @thingkingland )
Added support for streaming operator expressions (thanks to @thingkingland )
The parser now enforces language rules about which kinds of members are allowed in certain scopes
Added support for elaboration system tasks ($warning, $error, etc)
Added support for the $cast system task
Added support for chandles
Added support for events and event trigger statements
Added support for the wait_order statement
Finished remaining string and string-literal expressions and conversions

General Features

Added -Wunused-def (off by default) which warns about unused module/interface/program definitions
Added -Wno-top which warns if no top-level modules are found in a design
Added -Wtask-ignored for system tasks that get skipped during constant evaluation
Added -Wunsized-concat which warns for unsized integers used in concatenations
Added a --top option which can be used to manually specify the top-level modules in a design
The slang driver now reports the discovered top-level modules when elaborating unless --quiet is passed

Fixes

slang will no longer try to automatically instantiate unused modules that have interface ports
Cleaned up type checking that is performed in uninstantiated modules
Fixed the build to work for macOS (thanks to @thingkingland )
Fixed corner cases for assignment of unpacked arrays (thanks to @thingkingland )
Fixed a bug that prevented empty port connections from working correctly
Fixed a bug that prevented empty parameter assignments from working correctly
Fixed bugs related to constant evaluation involving mixed signedness of expressions (thanks to @thingkingland )
Fixed constant evaluation of shift operators with negative or unknown amounts (thanks to @thingkingland )
Fixed detection of whether statements are in a loop when those statements are in a nested level of block hierarchy
Fixed a preprocessor bug related to macro concatenation

[v0.4] - 2020-08-16

Highlights

This release contains a lot of internal refactoring and cleanup, with the goals of correctly handling all corner cases as well as dramatically speeding up compilation time -- some projects and workloads may see up to a 10x speedup.

Language Support

Support for intra-assignment timing controls
Full support for dynamic arrays in type checking and constant expressions
Full support for associative arrays in type checking and constant expressions
Partial support for queues in type checking and constant expressions (still missing expressions involving the '$' magic value)
Added $dimensions and $unpacked_dimensions system functions
Added $printtimescale, $timeformat, and $system functions
Added $ferror, $fgets, $fscanf, $sscanf, and $fread system functions
Support for disable statements
Support for unpacked array concatenations
Support for min:typ:max expressions
Support for disable-fork and wait-fork statements
String literals can now correctly be implicitly assigned to unpacked arrays of bytes (thanks to @thingkingland )

General Features

Reworked how definitions and instances are represented, both to make the code clearer as well as to allow caching of identical instances.
Timing controls are now included in AST->JSON serialization (thanks to @Kuree ).
Added initial support for generating simulation code for designs using LLVM. There's enough support here to simulate a basic "Hello World" example but not much else.
To facilitate code generation, a mid-level IR representation was added to sit between the AST and LLVM. In the future this could grow to be useful to other consumers as well.
Went through and removed experimental code analysis services from the repository and ported the CI build to GitHub actions, fixing the automated release and deployment pipeline in the process.
Split slang into several component libraries to make it easier to link in only subsets of functionality.
Added a bunch more API reference documentation.
The remaining 3rd party dependencies have been vendored into the repo under the external/ folder. The conan package manager has been removed from the build process.

Fixes

Fixed a bug where stringifying certain integer literals could produce garbage results.
Improved parser error recovery in more scenarios.
Fixed several crashes found by fuzz testing.
Empty concatenations now correctly report an error.
Fixed a faulty error reported when range-selecting a single bit from a big-endian vector.
Fixed the type that is inferred for implicitly typed parameters.
Rewrote lvalue handling in constant expressions to fix several corner cases.
Fixed a crash in the preprocessor involving a rare case of macro replacing a token that then becomes another macro.
Fixed parsing of cycle delays.
Fixed ANSI color output on Windows terminals.
Fixed variable lifetimes of task arguments.
Packed dimensions on enum declarations were previously being ignored.
Added additional error checking for various array creation rules.
Fixed an infinite loop in the parser caused by unsupported statements (thanks to @thingkingland ).
Fixed a bunch of issues with parsing new expressions.
Fixed a bunch of issues with parsing clocking blocks.
The error reported for non-standard character escape codes has been downgraded to a warning.

[v0.3] - 2020-03-24

Highlights

As of this release the preprocessor is 100% complete. This does not mean bug free (though I hope so!) but rather that all known features are finished, all known bugs are fixed, and there is 100% coverage in unit tests.

Language Support

Initial support for gate instantiations in the parser and AST
Tightened a bunch of parser rules for things like variable modifiers
Support parsing strength and delay modifiers in continuous assignments
Support creating implicit nets in all places allowed by the LRM
Full support for pragma directives in the preprocessor
$typename should now return the correct result for all types, as mandated by the LRM
Support for the type() operator in all places type references are allowed
Support for slicing packed and unpacked arrays across module array instantiations
Implement all rules related to variable lifetimes (static vs automatic)
Correctly prevent assignments to constants, nonblocking assignments to automatic variables
Support const'() casts
Support time literals, including all of the scaling and rounding rules

General Features

Lots of work was done on the documentation, CI builds, and the website. Check it out!
I removed most dependencies on 3rd party libraries that didn't do exactly what I wanted. This slims down the dependency tree and improved performance.
A bunch of improvements were made to the AST->JSON serialization (thanks @Kuree )
Printing of types in diagnostics was improved
Added a general system for correcting typos. For example:

module m;
    int someInt;
    int foo = someIn;
endmodule

source:3:15: error: use of undeclared identifier 'someIn'; did you mean 'someInt'?
    int foo = someIn;
              ^~~~~~
source:2:9: note: declared here
    int someInt;
        ^

Fixes

Lots of fixes to error recovery and error reporting in various cases
Struct members that required looking up type names was previously broken and has now been fixed
Fixed the check applied to enum initializers with unknown bits for 2-state base types
Port connections were previously not being type checked; that has been fixed
Fixed the result type of unary bitwise-not expressions

[v0.2] - 2020-01-20

This release fills in a bunch of missing holes and corner cases and cleans up a bunch of bugs. The first beginnings of a more structured release process and documentation system are in place.

This is the first release as of which feature support is tracked in the documentation.

[v0.1] - 2019-12-02

This is the first release of slang that is somewhat useful. The library supports lexing, preprocessing, parsing, type checking, and elaboration for a good portion of the language. The slang tool can be run on medium to large codebases and print out useful diagnostics.

There's still plenty of work to do but it seemed like a good idea to take a checkpoint.

Files

CHANGELOG.md

Latest commit

History

CHANGELOG.md

File metadata and controls

Change Log

[Unreleased]

Language Support

General Features

Improvements

Fixes

[v7.0] - 2024-09-26

Language Support

Clarifications in IEEE 1800-2023

New Features in IEEE 1800-2023

General Features

Improvements

Fixes

[v6.0] - 2024-04-21

Language Support

Clarifications in IEEE 1800-2023

New Features in IEEE 1800-2023

General Features

Improvements

Fixes

[v5.0] - 2023-12-26

Language Support

General Features

Improvements

Fixes

[v4.0] - 2023-08-10

Language Support

General Features

Improvements

Fixes

[v3.0] - 2023-03-18

Highlights

Language Support

General Features

Improvements

Fixes

[v2.0] - 2022-10-29

Highlights

Language Support

General Features

Improvements

Fixes

[v1.0] - 2022-06-25

Highlights

Language Support

General Features

Fixes

[v0.9] - 2022-01-06

Highlights

Language Support

General Features

Fixes

Extra Thanks

[v0.8] - 2021-08-14

Highlights

Language Support

General Features

Fixes

[v0.7] - 2021-04-02

Highlights

Language Support

General Features

Fixes

[v0.6] - 2021-01-10

Highlights

Language Support

General Features

Fixes

[v0.5] - 2020-10-26

Highlights

Language Support

General Features

Fixes

[v0.4] - 2020-08-16