binaryen fails to compile in Arch clean chroot

[anatol]

Hi, here is a followup for tinygo-org/tinygo#4332

I am trying to compile tinygo for Arch Linux in its clean build environment. tinygo in turn include binaryen (commit 11dba9b). Compilation for binaryen is invoked and it fails with

[161/230] Building CXX object src/passes/CMakeFiles/passes.dir/SimplifyLocals.cpp.o
FAILED: src/passes/CMakeFiles/passes.dir/SimplifyLocals.cpp.o 
/usr/bin/c++  -I/home/anatol/sources/tinygo/tinygo/lib/binaryen/src -I/home/anatol/sources/tinygo/tinygo/lib/binaryen/third_party/llvm-project/include -I/home/anatol/sources/tinygo/tinygo/lib/binaryen -O2 -pipe -fno-plt -fexceptions         -Wp,-D_FORTIFY_SOURCE=3 -Wformat -Werror=format-security         -fstack-clash-protection -fcf-protection         -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -Wp,-D_GLIBCXX_ASSERTIONS -g -DBUILD_LLVM_DWARF -Wall -Werror -Wextra -Wno-unused-parameter -fno-omit-frame-pointer -fno-rtti -Wno-implicit-int-float-conversion -Wno-unknown-warning-option -Wswitch -Wimplicit-fallthrough -Wnon-virtual-dtor -fPIC -fdiagnostics-color=always -O3 -DNDEBUG -UNDEBUG -std=c++17 -MD -MT src/passes/CMakeFiles/passes.dir/SimplifyLocals.cpp.o -MF src/passes/CMakeFiles/passes.dir/SimplifyLocals.cpp.o.d -o src/passes/CMakeFiles/passes.dir/SimplifyLocals.cpp.o -c /home/anatol/sources/tinygo/tinygo/lib/binaryen/src/passes/SimplifyLocals.cpp
In file included from /home/anatol/sources/tinygo/tinygo/lib/binaryen/src/parsing.h:29,
                 from /home/anatol/sources/tinygo/tinygo/lib/binaryen/src/wasm-builder.h:21,
                 from /home/anatol/sources/tinygo/tinygo/lib/binaryen/src/ir/literal-utils.h:20,
                 from /home/anatol/sources/tinygo/tinygo/lib/binaryen/src/ir/bits.h:21,
                 from /home/anatol/sources/tinygo/tinygo/lib/binaryen/src/ir/properties.h:20,
                 from /home/anatol/sources/tinygo/tinygo/lib/binaryen/src/ir/iteration.h:20,
                 from /home/anatol/sources/tinygo/tinygo/lib/binaryen/src/ir/branch-utils.h:20,
                 from /home/anatol/sources/tinygo/tinygo/lib/binaryen/src/passes/SimplifyLocals.cpp:50:
In constructor ‘wasm::Walker<SubType, VisitorType>::Task::Task(wasm::Walker<SubType, VisitorType>::TaskFunc, wasm::Expression**) [with SubType = wasm::LocalGetCounter; VisitorType = wasm::Visitor<wasm::LocalGetCounter, void>]’,
    inlined from ‘void wasm::SmallVector<T, N>::emplace_back(ArgTypes&& ...) [with ArgTypes = {void (*&)(wasm::LocalGetCounter*, wasm::Expression**), wasm::Expression**&}; T = wasm::Walker<wasm::LocalGetCounter, wasm::Visitor<wasm::LocalGetCounter, void> >::Task; long unsigned int N = 10]’ at /home/anatol/sources/tinygo/tinygo/lib/binaryen/src/support/small_vector.h:73:7,
    inlined from ‘void wasm::Walker<SubType, VisitorType>::pushTask(TaskFunc, wasm::Expression**) [with SubType = wasm::LocalGetCounter; VisitorType = wasm::Visitor<wasm::LocalGetCounter, void>]’ at /home/anatol/sources/tinygo/tinygo/lib/binaryen/src/wasm-traversal.h:314:23,
    inlined from ‘void wasm::Walker<SubType, VisitorType>::walk(wasm::Expression*&) [with SubType = wasm::LocalGetCounter; VisitorType = wasm::Visitor<wasm::LocalGetCounter, void>]’ at /home/anatol/sources/tinygo/tinygo/lib/binaryen/src/wasm-traversal.h:329:13,
    inlined from ‘void wasm::LocalGetCounter::analyze(wasm::Function*, wasm::Expression*)’ at /home/anatol/sources/tinygo/tinygo/lib/binaryen/src/ir/local-utils.h:37:9:
/home/anatol/sources/tinygo/tinygo/lib/binaryen/src/wasm-traversal.h:309:59: error: storing the address of local variable ‘ast’ in ‘*(std::array<wasm::Walker<wasm::LocalGetCounter, wasm::Visitor<wasm::LocalGetCounter, void> >::Task, 10>*)((char*)&_2->stack + 8).std::array<wasm::Walker<wasm::LocalGetCounter, wasm::Visitor<wasm::LocalGetCounter, void> >::Task, 10>::_M_elems[<unknown>].wasm::Walker<wasm::LocalGetCounter, wasm::Visitor<wasm::LocalGetCounter, void> >::Task::currp’ [-Werror=dangling-pointer=]
  309 |     Task(TaskFunc func, Expression** currp) : func(func), currp(currp) {}
      |                                                           ^~~~~~~~~~~~
In file included from /home/anatol/sources/tinygo/tinygo/lib/binaryen/src/passes/SimplifyLocals.cpp:54:
/home/anatol/sources/tinygo/tinygo/lib/binaryen/src/ir/local-utils.h: In member function ‘void wasm::LocalGetCounter::analyze(wasm::Function*, wasm::Expression*)’:
/home/anatol/sources/tinygo/tinygo/lib/binaryen/src/ir/local-utils.h:34:44: note: ‘ast’ declared here
   34 |   void analyze(Function* func, Expression* ast) {
      |                                ~~~~~~~~~~~~^~~
/home/anatol/sources/tinygo/tinygo/lib/binaryen/src/ir/local-utils.h:34:47: note: ‘this’ declared here
   34 |   void analyze(Function* func, Expression* ast) {
      |                                               ^
At global scope:
cc1plus: note: unrecognized command-line option ‘-Wno-unknown-warning-option’ may have been intended to silence earlier diagnostics
cc1plus: note: unrecognized command-line option ‘-Wno-implicit-int-float-conversion’ may have been intended to silence earlier diagnostics
cc1plus: all warnings being treated as errors
[169/230] Building CXX object src/wasm/CMakeFiles/wasm.dir/wat-parser.cpp.o
ninja: build stopped: subcommand failed.

Most likely the failure is related to one of the security fortfication flags used by Arch CXXFLAGS="-O2 -pipe -fno-plt -fexceptions -Wp,-D_FORTIFY_SOURCE=3 -Wformat -Werror=format-security -fstack-clash-protection -fcf-protection -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -Wp,-D_GLIBCXX_ASSERTIONS -g"

[kripken]

Hmm, we do take the address of a local there, but it is safe as the call to walk() will fully consume the data with that address. So this looks like a false positive.

But I'm not familiar with that error message so I'm not sure how best to work around it (or if there is a better solution than working around it).

[anatol]

I tried to google more about this problem. It looks like dangling-pointer warnings were added recently and are prone to false positives. But I don't really know GCC/C++ well enough to debug the problem.

Another part of the issue is that the project enables -Werror by default. Thus any warning (including false positive) becomes compilation error. tinygo plans to disable it by -DENABLE_WERROR=OFF.

[mtb0x1]

tinygo plans to disable it by -DENABLE_WERROR=OFF.

meanwhile you can try to skip compiling binaryen and use pre-built binaries (you need to install them).