Merge pull request #12144 from amyspark/fix-msvc-clangcl-linker-flag-detection

linkers: Fix detection of link arguments to Clang(-cl) + MSVC

mesonbuild/compilers/mixins/clang.py

@@ -11,7 +11,7 @@ import typing as T
 
 from ... import mesonlib
 from ...linkers.linkers import AppleDynamicLinker, ClangClDynamicLinker, LLVMDynamicLinker, GnuGoldDynamicLinker, \
-    MoldDynamicLinker
+    MoldDynamicLinker, MSVCDynamicLinker
 from ...mesonlib import OptionKey
 from ..compilers import CompileCheckMode
 from .gnu import GnuLikeCompiler
@@ -111,6 +111,13 @@ class ClangCompiler(GnuLikeCompiler):
             # Shouldn't work, but it'll be checked explicitly in the OpenMP dependency.
             return []
 
+    def gen_vs_module_defs_args(self, defsfile: str) -> T.List[str]:
+        if isinstance(self.linker, (MSVCDynamicLinker)):
+            # With MSVC, DLLs only export symbols that are explicitly exported,
+            # so if a module defs file is specified, we use that to export symbols
+            return ['-Wl,/DEF:' + defsfile]
+        return super().gen_vs_module_defs_args(defsfile)
+
     @classmethod
     def use_linker_args(cls, linker: str, version: str) -> T.List[str]:
         # Clang additionally can use a linker specified as a path, which GCC
@@ -155,6 +162,12 @@ class ClangCompiler(GnuLikeCompiler):
             args.extend(super().get_lto_compile_args(threads=threads))
         return args
 
+    def linker_to_compiler_args(self, args: T.List[str]) -> T.List[str]:
+        if isinstance(self.linker, (ClangClDynamicLinker, MSVCDynamicLinker)):
+            return [flag if flag.startswith('-Wl,') else f'-Wl,{flag}' for flag in args]
+        else:
+            return args
+
     def get_lto_link_args(self, *, threads: int = 0, mode: str = 'default',
                           thinlto_cache_dir: T.Optional[str] = None) -> T.List[str]:
         args = self.get_lto_compile_args(threads=threads, mode=mode)

mesonbuild/compilers/mixins/visualstudio.py

@@ -460,6 +460,18 @@ class ClangClCompiler(VisualStudioLikeCompiler):
             path = '.'
         return ['/clang:-isystem' + path] if is_system else ['-I' + path]
 
+    @classmethod
+    def use_linker_args(cls, linker: str, version: str) -> T.List[str]:
+        # Clang additionally can use a linker specified as a path, unlike MSVC.
+        if linker == 'lld-link':
+            return ['-fuse-ld=lld-link']
+        return super().use_linker_args(linker, version)
+
+    def linker_to_compiler_args(self, args: T.List[str]) -> T.List[str]:
+        # clang-cl forwards arguments span-wise with the /LINK flag
+        # therefore -Wl will be received by lld-link or LINK and rejected
+        return super().use_linker_args(self.linker.id, '') + super().linker_to_compiler_args([flag[4:] if flag.startswith('-Wl,') else flag for flag in args])
+
     def get_dependency_compile_args(self, dep: 'Dependency') -> T.List[str]:
         if dep.get_include_type() == 'system':
             converted: T.List[str] = []

mesonbuild/linkers/detect.py

@@ -55,6 +55,9 @@ def guess_win_linker(env: 'Environment', compiler: T.List[str], comp_class: T.Ty
     if value is not None:
         override = comp_class.use_linker_args(value[0], comp_version)
         check_args += override
+    elif 'lld-link' in compiler:
+        override = comp_class.use_linker_args('lld-link', comp_version)
+        check_args += override
 
     if extra_args is not None:
         check_args.extend(extra_args)

mesonbuild/linkers/linkers.py

@@ -1319,6 +1319,9 @@ class MSVCDynamicLinker(VisualStudioLikeLinkerMixin, DynamicLinker):
     def get_win_subsystem_args(self, value: str) -> T.List[str]:
         return self._apply_prefix([f'/SUBSYSTEM:{value.upper()}'])
 
+    def fatal_warnings(self) -> T.List[str]:
+        return ['-WX']
+
 
 class ClangClDynamicLinker(VisualStudioLikeLinkerMixin, DynamicLinker):
 
@@ -1348,6 +1351,9 @@ class ClangClDynamicLinker(VisualStudioLikeLinkerMixin, DynamicLinker):
     def get_thinlto_cache_args(self, path: str) -> T.List[str]:
         return ["/lldltocache:" + path]
 
+    def fatal_warnings(self) -> T.List[str]:
+        return ['-WX']
+
 
 class XilinkDynamicLinker(VisualStudioLikeLinkerMixin, DynamicLinker):
 

test cases/common/180 has link arg/meson.build

@@ -45,3 +45,23 @@ endif
 
 assert(cc.has_multi_link_arguments(is_arg), 'Arg that should have worked does not work.')
 assert(cc.has_multi_link_arguments([useless, is_arg]), 'Arg that should have worked does not work.')
+
+# These are Visual Studio only flags
+# Testing has_argument_syntax is incorrect as it skips Microsoft Clang
+if cc.get_define('_MSC_FULL_VER') != ''
+  if cc.get_linker_id() == 'link'
+    is_only = '/OPT:REF'
+    is_shared = '/GUARD:CF'
+  else # ld-link
+    is_only = '--color-diagnostics'
+    is_shared = '-guard:cf'
+  endif
+
+  # requires -Wl,xxx as it goes through the compiler
+  if cc.get_argument_syntax() != 'msvc'
+    is_only = '-Wl,@0@'.format(is_only)
+    is_shared = '-Wl,@0@'.format(is_shared)
+  endif
+
+  assert(cc.has_multi_link_arguments([is_only, is_shared]), 'Arg that should have worked does not work.')
+endif