r337290 - clang-cl: Postpone Wmsvc-not-found emission until link.exe gets used.

[Nico Weber via cfe-commits]

Author: nico
Date: Tue Jul 17 08:07:40 2018
New Revision: 337290

URL: http://llvm.org/viewvc/llvm-project?rev=337290&view=rev
Log:
clang-cl: Postpone Wmsvc-not-found emission until link.exe gets used.

Wmsvc-not-found was added in r297851 to help diagnose why link.exe can't be
executed. However, it's emitted even when using -fuse-ld=lld, and in cross
builds there's no way to get rid of the warning other than disabling it.

Instead, emit it when we look up link.exe and it ends up not being executable.
That way, when passing -fuse-ld=lld it will never be printed.
It will also not be printed if we find link.exe on PATH.

(We might want to eventually default to lld one day, at least when running on a
non-Win host, but that's for another day.)

Fixes PR38016.

Modified:
    cfe/trunk/lib/Driver/ToolChains/MSVC.cpp
    cfe/trunk/lib/Driver/ToolChains/MSVC.h

Modified: cfe/trunk/lib/Driver/ToolChains/MSVC.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/ToolChains/MSVC.cpp?rev=337290&r1=337289&r2=337290&view=diff
==============================================================================
--- cfe/trunk/lib/Driver/ToolChains/MSVC.cpp (original)
+++ cfe/trunk/lib/Driver/ToolChains/MSVC.cpp Tue Jul 17 08:07:40 2018
@@ -469,6 +469,9 @@ void visualstudio::Linker::ConstructJob(
     // their own link.exe which may come first.
     linkPath = FindVisualStudioExecutable(TC, "link.exe");
 
+    if (!TC.FoundMSVCInstall() && !llvm::sys::fs::can_execute(linkPath))
+      C.getDriver().Diag(clang::diag::warn_drv_msvc_not_found);
+
 #ifdef _WIN32
     // When cross-compiling with VS2017 or newer, link.exe expects to have
     // its containing bin directory at the top of PATH, followed by the
@@ -684,8 +687,6 @@ MSVCToolChain::MSVCToolChain(const Drive
 }
 
 Tool *MSVCToolChain::buildLinker() const {
-  if (VCToolChainPath.empty())
-    getDriver().Diag(clang::diag::warn_drv_msvc_not_found);
   return new tools::visualstudio::Linker(*this);
 }
 

Modified: cfe/trunk/lib/Driver/ToolChains/MSVC.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/ToolChains/MSVC.h?rev=337290&r1=337289&r2=337290&view=diff
==============================================================================
--- cfe/trunk/lib/Driver/ToolChains/MSVC.h (original)
+++ cfe/trunk/lib/Driver/ToolChains/MSVC.h Tue Jul 17 08:07:40 2018
@@ -123,6 +123,8 @@ public:
 
   void printVerboseInfo(raw_ostream &OS) const override;
 
+  bool FoundMSVCInstall() const { return !VCToolChainPath.empty(); }
+
 protected:
   void AddSystemIncludeWithSubfolder(const llvm::opt::ArgList &DriverArgs,
                                      llvm::opt::ArgStringList &CC1Args,