Driver: correct behaviour of -fmsc-version=MAJOR

Ensure that we properly handle the case where just the major version component
is provided by the user.

Thanks to Alp Toker for pointing out that this was not handled correctly!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@211506 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Frontend/CompilerInvocation.cpp

@@ -1223,7 +1223,11 @@ static unsigned parseMSCVersion(ArgList &Args, DiagnosticsEngine &Diags) {
         << Arg->getAsString(Args) << Value;
       return 0;
     }
-    return (Version < 100000) ? Version * 100000 : Version;
+    if (Version < 100)
+      Version = Version * 100;    // major -> major.minor
+    if (Version < 100000)
+      Version = Version * 100000; // major.minor -> major.minor.build
+    return Version;
   }
 
   // parse the dot-delimited component version

test/Driver/msc-version.c

@@ -16,6 +16,12 @@
 // CHECK-MSC-VERSION-EXT: _MSC_FULL_VER 160030319
 // CHECK-MSC-VERSION-EXT: _MSC_VER 1600
 
+// RUN: %clang -target i686-windows -fms-compatibility -fmsc-version=14 -dM -E - </dev/null -o - | FileCheck %s -check-prefix CHECK-MSC-VERSION-MAJOR
+
+// CHECK-MSC-VERSION-MAJOR: _MSC_BUILD 1
+// CHECK-MSC-VERSION-MAJOR: _MSC_FULL_VER 140000000
+// CHECK-MSC-VERSION-MAJOR: _MSC_VER 1400
+
 // RUN: %clang -target i686-windows -fms-compatibility -fmsc-version=17.00 -dM -E - </dev/null -o - | FileCheck %s -check-prefix CHECK-MSC-VERSION-MAJOR-MINOR
 
 // CHECK-MSC-VERSION-MAJOR-MINOR: _MSC_BUILD 1