[clang] ebe6d3b - [clang] Don't default to a specifically shared libunwind on mingw with a g++ driver

[Martin Storsjö via cfe-commits]

Author: Martin Storsjö
Date: 2021-03-06T08:50:46+02:00
New Revision: ebe6d3be0f73c15e64b1ebafd2a4b9fa836be78c

URL: https://github.com/llvm/llvm-project/commit/ebe6d3be0f73c15e64b1ebafd2a4b9fa836be78c
DIFF: https://github.com/llvm/llvm-project/commit/ebe6d3be0f73c15e64b1ebafd2a4b9fa836be78c.diff

LOG: [clang] Don't default to a specifically shared libunwind on mingw with a g++ driver

For MinGW targets, we distinguish between an explicitly shared unwinder
library (requested via -shared-libgcc), an explicitly static one
(requested via -static-libgcc or -static) and the default case (which
just passes -lunwind to the linker, which will pick either shared or
static depending on what's available, with the normal linker logic).

This makes the implicit default case (as added in D79995) actually work as
it was intended, when using the g++ driver (which is the main usecase for
libunwind as far as I know).

Differential Revision: https://reviews.llvm.org/D98023

Added: 
    

Modified: 
    clang/lib/Driver/ToolChains/CommonArgs.cpp
    clang/test/Driver/compiler-rt-unwind.c

Removed: 
    


################################################################################
diff  --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 46a0fc67ced0..5afb213a178b 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1382,7 +1382,9 @@ static LibGccType getLibGccType(const ToolChain &TC, const Driver &D,
   // The Android NDK only provides libunwind.a, not libunwind.so.
   if (TC.getTriple().isAndroid())
     return LibGccType::StaticLibGcc;
-  if (D.CCCIsCXX())
+  // For MinGW, don't imply a shared libgcc here, we only want to return
+  // SharedLibGcc if that was explicitly requested.
+  if (D.CCCIsCXX() && !TC.getTriple().isOSCygMing())
     return LibGccType::SharedLibGcc;
   return LibGccType::UnspecifiedLibGcc;
 }

diff  --git a/clang/test/Driver/compiler-rt-unwind.c b/clang/test/Driver/compiler-rt-unwind.c
index e21916d41f93..86c2c9b982c3 100644
--- a/clang/test/Driver/compiler-rt-unwind.c
+++ b/clang/test/Driver/compiler-rt-unwind.c
@@ -69,5 +69,9 @@
 // RUN:     --target=x86_64-w64-mingw32 -rtlib=compiler-rt --unwindlib=libunwind \
 // RUN:     --gcc-toolchain="" \
 // RUN:   | FileCheck --check-prefix=MINGW-RTLIB-COMPILER-RT-UNWINDLIB-COMPILER-RT %s
+// RUN: %clangxx -no-canonical-prefixes %s -### -o %t.o 2>&1 \
+// RUN:     --target=x86_64-w64-mingw32 -rtlib=compiler-rt --unwindlib=libunwind \
+// RUN:     --gcc-toolchain="" \
+// RUN:   | FileCheck --check-prefix=MINGW-RTLIB-COMPILER-RT-UNWINDLIB-COMPILER-RT %s
 // MINGW-RTLIB-COMPILER-RT-UNWINDLIB-COMPILER-RT: "{{.*}}libclang_rt.builtins-x86_64.a"
 // MINGW-RTLIB-COMPILER-RT-UNWINDLIB-COMPILER-RT: "{{.*}}lunwind"