Fix symbol visibility issues on Linux for plugins

CMakeLists.txt

@@ -254,8 +254,9 @@ if(NOT WIN32 AND NOT CYGWIN)
     # weak symbol Y means the weak symbol cannot be overridden at runtime. This was likely caused by
     # different translation units being compiled with different visibility settings."
     # See LLVM's cmake/modules/HandleLLVMOptions.cmake.
+    # For plugins, we shouldn't apply this flag because it hides the inline methods of e.g. Visitor.
     check_cxx_compiler_flag("-fvisibility-inlines-hidden" SUPPORTS_FVISIBILITY_INLINES_HIDDEN_FLAG)
-    if (${SUPPORTS_FVISIBILITY_INLINES_HIDDEN_FLAG})
+    if (${SUPPORTS_FVISIBILITY_INLINES_HIDDEN_FLAG} AND NOT LDC_ENABLE_PLUGINS)
         append("-fvisibility-inlines-hidden" LDC_CXXFLAGS)
     endif()
 endif()
@@ -683,10 +684,13 @@ if(LDC_ENABLE_PLUGINS)
 
         if(LINKER_ACCEPTS_EXPORT_DYNAMIC_FLAG)
             set(LDC_LINKERFLAG_LIST "${LDC_LINKERFLAG_LIST};-Wl,--export-dynamic")
+        else()
+            message(WARNING "Linker does not accept --export-dynamic, user plugins may give missing symbol errors upon load")
         endif()
     endif()
 endif()
 message(STATUS "-- Building LDC with plugin support (LDC_ENABLE_PLUGINS): ${LDC_ENABLE_PLUGINS}")
+message(STATUS "-- Linking LDC with flags: ${ALTERNATIVE_MALLOC_O};${LDC_LINKERFLAG_LIST}")
 
 build_d_executable(
     "${LDC_EXE}"

cmake/Modules/BuildDExecutable.cmake

@@ -40,7 +40,8 @@ function(build_d_executable target_name output_exe d_src_files compiler_args lin
         # Compile all D modules to a single object.
         set(object_file ${PROJECT_BINARY_DIR}/obj/${target_name}${CMAKE_CXX_OUTPUT_EXTENSION})
         # Default to -linkonce-templates with LDMD host compiler, to speed-up optimization.
-        if("${D_COMPILER_ID}" STREQUAL "LDMD")
+        # Note: for plugin support we need the symbols to be global, don't use -linkonce-templates.
+        if("${D_COMPILER_ID}" STREQUAL "LDMD" AND NOT LDC_ENABLE_PLUGINS)
             set(dflags -linkonce-templates ${dflags})
         endif()
         add_custom_command(
@@ -105,7 +106,7 @@ function(build_d_executable target_name output_exe d_src_files compiler_args lin
 
         add_custom_command(
             OUTPUT ${output_exe}
-            COMMAND ${D_COMPILER} ${dflags} -of${output_exe} ${objects_args} ${dep_libs} ${translated_linker_args}
+            COMMAND ${D_COMPILER} ${dflags} -of${output_exe} ${objects_args} ${dep_libs} ${translated_linker_args} -fvisibility=public
             WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
             DEPENDS ${target_name}_d_objects ${object_files} ${link_deps}
         )

tests/plugins/lit.local.cfg

@@ -24,17 +24,16 @@ if (config.plugins_supported):
     config.substitutions.append( ('%plugin_compile_flags', " ".join(plugin_compile_flags) ) )
 
     # Set feature that tells us that the just-built LDC is ABI compatible with the host D compiler
-    # Be conservative: only set it when host LDC and just-built LDC have identical versions
+    # For our tets, the required ABI compatibility is OK since LDC 1.18 (interface ptr).
+    # If the compiler is built not by LDC but another compiler, then assume the ABI to be incompatible.
     command = [config.ldc2_bin, '--version']
     p = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True)
     text1 = p.stdout.readline() # Ex.: "LDC - the LLVM D compiler (1.33.0-git-716f627)"
     text2 = p.stdout.readline() # Ex.: "  based on DMD v2.103.1 and LLVM 14.0.0"
     text3 = p.stdout.readline() # Ex.: "  built with LDC - the LLVM D compiler (1.33.0-beta2)"
-    m = re.compile('LDC - the LLVM D compiler \((.*)\)').match(text1)
-    ldc_version = m.group(1)
-    m3 = re.compile('  built with.* \((.*)\)').match(text3)
-    host_version = m3.group(1)
-    if (ldc_version == host_version):
+    host_version = re.compile('  built with LDC.* \((1\.[0-9]+).*\)').match(text3).group(1)
+    print(host_version)
+    if (float(host_version) > 1.1799):
         config.available_features.add('ABI_compatible_with_host_D')