[clang] [clang][flang][windows] Prefer user-provided library paths (-L) (PR #90758)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: David Truby (DavidTruby)

<details>
<summary>Changes</summary>

Currently the paths to compiler-rt and the Flang runtimes from the LLVM build/install directory are preferred over any user-provided library paths. This means a user can't override compiler-rt or the Flang runtimes with custom versions.

This patch changes the link order to prefer library paths specified with -L over the LLVM paths. This matches the behaviour of clang and flang on Linux.

---
Full diff: https://github.com/llvm/llvm-project/pull/90758.diff


1 Files Affected:

- (modified) clang/lib/Driver/ToolChains/MSVC.cpp (+4-4) 


``````````diff
diff --git a/clang/lib/Driver/ToolChains/MSVC.cpp b/clang/lib/Driver/ToolChains/MSVC.cpp
index fbf2f45b543844..b7021d4b996ddd 100644
--- a/clang/lib/Driver/ToolChains/MSVC.cpp
+++ b/clang/lib/Driver/ToolChains/MSVC.cpp
@@ -134,6 +134,10 @@ void visualstudio::Linker::ConstructJob(Compilation &C, const JobAction &JA,
           Args.MakeArgString(std::string("-libpath:") + WindowsSdkLibPath));
   }
 
+  if (!C.getDriver().IsCLMode() && Args.hasArg(options::OPT_L))
+    for (const auto &LibPath : Args.getAllArgValues(options::OPT_L))
+      CmdArgs.push_back(Args.MakeArgString("-libpath:" + LibPath));
+
   if (C.getDriver().IsFlangMode()) {
     addFortranRuntimeLibraryPath(TC, Args, CmdArgs);
     addFortranRuntimeLibs(TC, Args, CmdArgs);
@@ -154,10 +158,6 @@ void visualstudio::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   if (TC.getVFS().exists(CRTPath))
     CmdArgs.push_back(Args.MakeArgString("-libpath:" + CRTPath));
 
-  if (!C.getDriver().IsCLMode() && Args.hasArg(options::OPT_L))
-    for (const auto &LibPath : Args.getAllArgValues(options::OPT_L))
-      CmdArgs.push_back(Args.MakeArgString("-libpath:" + LibPath));
-
   CmdArgs.push_back("-nologo");
 
   if (Args.hasArg(options::OPT_g_Group, options::OPT__SLASH_Z7))

``````````

</details>


https://github.com/llvm/llvm-project/pull/90758