[MinGW] Skip adding default win32 api libraries if -lwindowsapp is specified

In this setup, skip adding all the default windows import libraries,
if linking to windowsapp (which replaces them, when targeting the
windows store/UWP api subset).

With GCC, the same is achieved by using a custom spec file, but
since clang doesn't use spec files, we have to allow other means of
overriding what default libraries to use (without going all the
way to using -nostdlib, which would exclude everything). The same
approach, in detecting certain user specified libraries and omitting
others from the defaults, was already used in SVN r314138.

Differential Revision: https://reviews.llvm.org/D49059

llvm-svn: 336655

2 files changed, 26 insertions, 8 deletions

diff --git a/clang/lib/Driver/ToolChains/MinGW.cpp b/clang/lib/Driver/ToolChains/MinGW.cpp
index da71a84b760..a88e00f0c8e 100644
--- a/clang/lib/Driver/ToolChains/MinGW.cpp
+++ b/clang/lib/Driver/ToolChains/MinGW.cpp
@@ -201,6 +201,14 @@ void tools::MinGW::Linker::ConstructJob(Compilation &C, const JobAction &JA,
       CmdArgs.push_back("-Bdynamic");
   }
 
+  bool HasWindowsApp = false;
+  for (auto Lib : Args.getAllArgValues(options::OPT_l)) {
+    if (Lib == "windowsapp") {
+      HasWindowsApp = true;
+      break;
+    }
+  }
+
   if (!Args.hasArg(options::OPT_nostdlib)) {
     if (!Args.hasArg(options::OPT_nodefaultlibs)) {
       if (Args.hasArg(options::OPT_static))
@@ -223,15 +231,19 @@ void tools::MinGW::Linker::ConstructJob(Compilation &C, const JobAction &JA,
       if (Args.hasArg(options::OPT_pthread))
         CmdArgs.push_back("-lpthread");
 
-      // add system libraries
-      if (Args.hasArg(options::OPT_mwindows)) {
-        CmdArgs.push_back("-lgdi32");
-        CmdArgs.push_back("-lcomdlg32");
+      if (!HasWindowsApp) {
+        // Add system libraries. If linking to libwindowsapp.a, that import
+        // library replaces all these and we shouldn't accidentally try to
+        // link to the normal desktop mode dlls.
+        if (Args.hasArg(options::OPT_mwindows)) {
+          CmdArgs.push_back("-lgdi32");
+          CmdArgs.push_back("-lcomdlg32");
+        }
+        CmdArgs.push_back("-ladvapi32");
+        CmdArgs.push_back("-lshell32");
+        CmdArgs.push_back("-luser32");
+        CmdArgs.push_back("-lkernel32");
       }
-      CmdArgs.push_back("-ladvapi32");
-      CmdArgs.push_back("-lshell32");
-      CmdArgs.push_back("-luser32");
-      CmdArgs.push_back("-lkernel32");
 
       if (Args.hasArg(options::OPT_static))
         CmdArgs.push_back("--end-group");
diff --git a/clang/test/Driver/mingw-windowsapp.c b/clang/test/Driver/mingw-windowsapp.c
new file mode 100644
index 00000000000..bf6f2ec3fa3
--- /dev/null
+++ b/clang/test/Driver/mingw-windowsapp.c
@@ -0,0 +1,6 @@
+// RUN: %clang -v -target i686-pc-windows-gnu -### %s 2>&1 | FileCheck -check-prefix=CHECK_DEFAULT %s
+// RUN: %clang -v -target i686-pc-windows-gnu -### %s -lwindowsapp 2>&1 | FileCheck -check-prefix=CHECK_WINDOWSAPP %s
+
+// CHECK_DEFAULT: "-lmsvcrt" "-ladvapi32" "-lshell32" "-luser32" "-lkernel32" "-lmingw32"
+// CHECK_WINDOWSAPP: "-lwindowsapp" "-lmingw32"
+// CHECK_WINDOWSAPP-SAME: "-lmsvcrt" "-lmingw32"