Linker: Generate per-language module -DEF: flags on Windows

With IntelLLVM on Windows, we link using the compiler driver. With MSVC on Windows, we invoke the linker directly. If we use both in a single build tree, for separate languages, the value of `CMAKE_LINK_DEF_FILE_FLAG` conflicts. Add a per-language `CMAKE_<LANG>_LINK_DEF_FILE_FLAG` variable to avoid the conflict. Preserve the language-agnostic variable for compatibility with projects that reference it. Fixes: #26005
2026-01-11 16:32:14 -06:00 · 2025-05-28 13:19:21 -04:00
parent 9ffbef62ca
commit 8b710d8264
14 changed files with 48 additions and 11 deletions
--- a/Help/manual/cmake-variables.7.rst
+++ b/Help/manual/cmake-variables.7.rst
@@ -493,6 +493,7 @@ Variables that Control the Build
   /variable/CMAKE_LANG_COMPILER_LAUNCHER
   /variable/CMAKE_LANG_CPPCHECK
   /variable/CMAKE_LANG_CPPLINT
+   /variable/CMAKE_LANG_LINK_DEF_FILE_FLAG
   /variable/CMAKE_LANG_ICSTAT
   /variable/CMAKE_LANG_INCLUDE_WHAT_YOU_USE
   /variable/CMAKE_LANG_LINK_GROUP_USING_FEATURE
--- a/Help/variable/CMAKE_LANG_LINK_DEF_FILE_FLAG.rst
+++ b/Help/variable/CMAKE_LANG_LINK_DEF_FILE_FLAG.rst
@@ -0,0 +1,14 @@
+CMAKE_<LANG>_LINK_DEF_FILE_FLAG
+-------------------------------
+
+.. versionadded:: 4.1
+
+Linker flag to be used to specify a ``.def`` file for dll creation
+with the toolchain for language ``<LANG>``.
+
+CMake sets this variable automatically during toolchain inspection by
+calls to the :command:`project` or :command:`enable_language` commands.
+
+If the :variable:`!CMAKE_<LANG>_LINK_DEF_FILE_FLAG` variable
+is defined, it takes precedence over the language-agnostic
+:variable:`CMAKE_LINK_DEF_FILE_FLAG` variable.
--- a/Help/variable/CMAKE_LINK_DEF_FILE_FLAG.rst
+++ b/Help/variable/CMAKE_LINK_DEF_FILE_FLAG.rst
@@ -5,3 +5,9 @@ Linker flag to be used to specify a ``.def`` file for dll creation.

 The flag will be used to add a ``.def`` file when creating a dll on
 Windows; this is only defined on Windows.
+
+CMake sets this variable automatically during toolchain inspection by
+calls to the :command:`project` or :command:`enable_language` commands.
+
+If the per-language :variable:`CMAKE_<LANG>_LINK_DEF_FILE_FLAG` variable
+is defined, it takes precedence over :variable:`!CMAKE_LINK_DEF_FILE_FLAG`.
--- a/Modules/Platform/Windows-Clang.cmake
+++ b/Modules/Platform/Windows-Clang.cmake
@@ -33,7 +33,8 @@ macro(__windows_compiler_clang_gnu lang)
  set(CMAKE_FIND_LIBRARY_PREFIXES "lib" "")
  set(CMAKE_FIND_LIBRARY_SUFFIXES ".dll.a" ".a" ".lib")
  set(CMAKE_SUPPORT_WINDOWS_EXPORT_ALL_SYMBOLS 1)
-  set (CMAKE_LINK_DEF_FILE_FLAG "-Xlinker /DEF:")
+  set(CMAKE_${lang}_LINK_DEF_FILE_FLAG "-Xlinker /DEF:")
+  set(CMAKE_LINK_DEF_FILE_FLAG "${CMAKE_${lang}_LINK_DEF_FILE_FLAG}")

  set(CMAKE_${lang}_LINKER_WRAPPER_FLAG "-Xlinker" " ")
  set(CMAKE_${lang}_LINKER_WRAPPER_FLAG_SEP)
--- a/Modules/Platform/Windows-GNU.cmake
+++ b/Modules/Platform/Windows-GNU.cmake
@@ -127,6 +127,8 @@ macro(__windows_compiler_gnu lang)
    set(CMAKE_${lang}_RESPONSE_FILE_LINK_FLAG "@")
  endif()

+  set(CMAKE_${lang}_LINK_DEF_FILE_FLAG "") # Empty string: passing the file is enough
+
  # Binary link rules.
  set(CMAKE_${lang}_CREATE_SHARED_MODULE
    "<CMAKE_${lang}_COMPILER> <CMAKE_SHARED_MODULE_${lang}_FLAGS> <LANGUAGE_COMPILE_FLAGS> <LINK_FLAGS> <CMAKE_SHARED_MODULE_CREATE_${lang}_FLAGS> -o <TARGET> ${CMAKE_GNULD_IMAGE_VERSION} <OBJECTS> <LINK_LIBRARIES>")
--- a/Modules/Platform/Windows-IntelLLVM.cmake
+++ b/Modules/Platform/Windows-IntelLLVM.cmake
@@ -35,7 +35,8 @@ macro(__windows_compiler_intel lang)

  set(CMAKE_${lang}_CREATE_WIN32_EXE "${CMAKE_${lang}_LINKER_WRAPPER_FLAG}/subsystem:windows")
  set(CMAKE_${lang}_CREATE_CONSOLE_EXE "${CMAKE_${lang}_LINKER_WRAPPER_FLAG}/subsystem:console")
-  set(CMAKE_LINK_DEF_FILE_FLAG "${CMAKE_${lang}_LINKER_WRAPPER_FLAG}/DEF:")
+  set(CMAKE_${lang}_LINK_DEF_FILE_FLAG "${CMAKE_${lang}_LINKER_WRAPPER_FLAG}/DEF:")
+  set(CMAKE_LINK_DEF_FILE_FLAG "${CMAKE_${lang}_LINK_DEF_FILE_FLAG}")
  set(CMAKE_LIBRARY_PATH_FLAG "${CMAKE_${lang}_LINKER_WRAPPER_FLAG}/LIBPATH:")

  set(CMAKE_${lang}_LINK_EXECUTABLE
--- a/Modules/Platform/Windows-MSVC.cmake
+++ b/Modules/Platform/Windows-MSVC.cmake
@@ -396,6 +396,7 @@ macro(__windows_compiler_msvc lang)
  set(CMAKE_${lang}_CREATE_ASSEMBLY_SOURCE
    "<CMAKE_${lang}_COMPILER> ${CMAKE_START_TEMP_FILE} ${CMAKE_CL_NOLOGO}${_COMPILE_${lang}} <DEFINES> <INCLUDES> <FLAGS> /FoNUL /FAs /Fa<ASSEMBLY_SOURCE> /c <SOURCE>${CMAKE_END_TEMP_FILE}")

+  set(CMAKE_${lang}_LINK_DEF_FILE_FLAG "/DEF:")
  set(CMAKE_${lang}_USE_RESPONSE_FILE_FOR_OBJECTS 1)
  set(CMAKE_${lang}_LINK_EXECUTABLE
    "${_CMAKE_VS_LINK_EXE}<CMAKE_LINKER> ${CMAKE_CL_NOLOGO} <OBJECTS> ${CMAKE_START_TEMP_FILE} /out:<TARGET> /implib:<TARGET_IMPLIB> /pdb:<TARGET_PDB> /version:<TARGET_VERSION_MAJOR>.<TARGET_VERSION_MINOR>${_PLATFORM_LINK_FLAGS} <CMAKE_${lang}_LINK_FLAGS> <LINK_FLAGS> <LINK_LIBRARIES>${CMAKE_END_TEMP_FILE}")
--- a/Modules/Platform/Windows-PGI.cmake
+++ b/Modules/Platform/Windows-PGI.cmake
@@ -37,6 +37,8 @@ else()
 endif()

 macro(__windows_compiler_pgi lang)
+  set(CMAKE_${lang}_LINK_DEF_FILE_FLAG "-def:")
+
  # Shared library compile and link rules.
  set(CMAKE_${lang}_CREATE_STATIC_LIBRARY "lib ${CMAKE_CL_NOLOGO} <LINK_FLAGS> /out:<TARGET> <OBJECTS> ")
  set(CMAKE_${lang}_CREATE_SHARED_LIBRARY "<CMAKE_${lang}_COMPILER> ${CMAKE_START_TEMP_FILE} -Mmakedll -implib:<TARGET_IMPLIB> -Xlinker -pdb:<TARGET_PDB> -Xlinker -version:<TARGET_VERSION_MAJOR>.<TARGET_VERSION_MINOR> <LINK_FLAGS> -o <TARGET> <OBJECTS> <LINK_LIBRARIES> ${CMAKE_END_TEMP_FILE}")
--- a/Source/cmLocalGenerator.cxx
+++ b/Source/cmLocalGenerator.cxx
@@ -1673,7 +1673,7 @@ void cmLocalGenerator::GetTargetFlags(
  this->AppendWarningAsErrorLinkerFlags(extraLinkFlags, target, linkLanguage);
  this->AppendIPOLinkerFlags(extraLinkFlags, target, config, linkLanguage);
  this->AppendModuleDefinitionFlag(extraLinkFlags, target, linkLineComputer,
-                                   config);
+                                   config, linkLanguage);

  if (!extraLinkFlags.empty()) {
    this->GetGlobalGenerator()->EncodeLiteral(extraLinkFlags);
@@ -3615,7 +3615,8 @@ std::string cmLocalGenerator::GetLinkDependencyFile(

 void cmLocalGenerator::AppendModuleDefinitionFlag(
  std::string& flags, cmGeneratorTarget const* target,
-  cmLinkLineComputer* linkLineComputer, std::string const& config)
+  cmLinkLineComputer* linkLineComputer, std::string const& config,
+  std::string const& lang)
 {
  cmGeneratorTarget::ModuleDefinitionInfo const* mdi =
    target->GetModuleDefinitionInfo(config);
@@ -3623,8 +3624,11 @@ void cmLocalGenerator::AppendModuleDefinitionFlag(
    return;
  }

-  cmValue defFileFlag =
-    this->Makefile->GetDefinition("CMAKE_LINK_DEF_FILE_FLAG");
+  cmValue defFileFlag = this->Makefile->GetDefinition(
+    cmStrCat("CMAKE_", lang, "_LINK_DEF_FILE_FLAG"));
+  if (!defFileFlag) {
+    defFileFlag = this->Makefile->GetDefinition("CMAKE_LINK_DEF_FILE_FLAG");
+  }
  if (!defFileFlag) {
    return;
  }
--- a/Source/cmLocalGenerator.h
+++ b/Source/cmLocalGenerator.h
@@ -192,7 +192,8 @@ public:
  void AppendModuleDefinitionFlag(std::string& flags,
                                  cmGeneratorTarget const* target,
                                  cmLinkLineComputer* linkLineComputer,
-                                  std::string const& config);
+                                  std::string const& config,
+                                  std::string const& lang);
  bool AppendLWYUFlags(std::string& flags, cmGeneratorTarget const* target,
                       std::string const& lang);

--- a/Source/cmMakefileExecutableTargetGenerator.cxx
+++ b/Source/cmMakefileExecutableTargetGenerator.cxx
@@ -421,7 +421,7 @@ void cmMakefileExecutableTargetGenerator::WriteExecutableRule(bool relink)

    this->LocalGenerator->AppendModuleDefinitionFlag(
      linkFlags, this->GeneratorTarget, linkLineComputer.get(),
-      this->GetConfigName());
+      this->GetConfigName(), linkLanguage);
  }

  this->LocalGenerator->AppendIPOLinkerFlags(
--- a/Source/cmMakefileLibraryTargetGenerator.cxx
+++ b/Source/cmMakefileLibraryTargetGenerator.cxx
@@ -188,7 +188,7 @@ void cmMakefileLibraryTargetGenerator::WriteSharedLibraryRules(bool relink)

  this->LocalGenerator->AppendModuleDefinitionFlag(
    extraFlags, this->GeneratorTarget, linkLineComputer.get(),
-    this->GetConfigName());
+    this->GetConfigName(), linkLanguage);

  this->UseLWYU = this->LocalGenerator->AppendLWYUFlags(
    extraFlags, this->GeneratorTarget, linkLanguage);
@@ -224,7 +224,7 @@ void cmMakefileLibraryTargetGenerator::WriteModuleLibraryRules(bool relink)

  this->LocalGenerator->AppendModuleDefinitionFlag(
    extraFlags, this->GeneratorTarget, linkLineComputer.get(),
-    this->GetConfigName());
+    this->GetConfigName(), linkLanguage);

  this->UseLWYU = this->LocalGenerator->AppendLWYUFlags(
    extraFlags, this->GeneratorTarget, linkLanguage);
--- a/Tests/ModuleDefinition/CMakeLists.txt
+++ b/Tests/ModuleDefinition/CMakeLists.txt
@@ -1,6 +1,10 @@
 cmake_minimum_required(VERSION 3.10)
 project(ModuleDefinition C)

+# Simulate another language overriding the -DEF: flag.
+# The generators now prefer CMAKE_<LANG>_LINK_DEF_FILE_FLAG.
+set(CMAKE_LINK_DEF_FILE_FLAG "bad-def-flag:")
+
 # Test .def file source recognition for DLLs.
 add_library(example_dll SHARED example_dll.c example_dll.def)

--- a/Tests/ObjectLibrary/CMakeLists.txt
+++ b/Tests/ObjectLibrary/CMakeLists.txt
@@ -32,7 +32,7 @@ target_link_libraries(UseABstatic ABstatic)
 # Test module definition file to export object library symbols in the test
 # below if the platform needs and supports it.
 set(ABshared_SRCS $<TARGET_OBJECTS:A>)
-if(CMAKE_LINK_DEF_FILE_FLAG OR NOT WIN32)
+if(CMAKE_C_LINK_DEF_FILE_FLAG OR NOT WIN32)
  list(APPEND ABshared_SRCS $<TARGET_OBJECTS:B> AB.def)
 else()
  set(NO_A NO_A)