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

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

2 files changed, 26 insertions, 1 deletions

diff --git a/mesonbuild/compilers/mixins/clang.py b/mesonbuild/compilers/mixins/clang.py
index a57b9a9..f982509 100644
--- a/mesonbuild/compilers/mixins/clang.py
+++ b/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)
diff --git a/mesonbuild/compilers/mixins/visualstudio.py b/mesonbuild/compilers/mixins/visualstudio.py
index d6ebd6e..4e2ce09 100644
--- a/mesonbuild/compilers/mixins/visualstudio.py
+++ b/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] = []