/*Syntactic=*/LangOpts.MicrosoftExt))
Diag(MI->getDefinitionLoc(), diag::warn_pp_macro_def_mismatch_with_pch)
<< MacroNameTok.getIdentifierInfo();
- return;
+ // Issue the diagnostic but allow the change if msvc extensions are enabled
+ if (!LangOpts.MicrosoftExt)
+ return;
}
// Finally, if this identifier already had a macro defined for it, verify that
--- /dev/null
+// Test -D and -U interaction with a PCH when -fms-extensions is enabled.
+
+// RUN: %clang_cc1 -DFOO %S/variables.h -emit-pch -o %t1.pch
+
+// RUN: not %clang_cc1 -DFOO=blah -DBAR=int -include-pch %t1.pch -pch-through-header=%S/variables.h %s 2> %t.err
+// RUN: FileCheck -check-prefix=CHECK-FOO %s < %t.err
+
+// RUN: not %clang_cc1 -UFOO -DBAR=int -include-pch %t1.pch %s -pch-through-header=%S/variables.h 2> %t.err
+// RUN: FileCheck -check-prefix=CHECK-NOFOO %s < %t.err
+
+// RUN: %clang_cc1 -include-pch %t1.pch -DBAR=int -pch-through-header=%S/variables.h -verify %s 2> %t.err
+
+// Enabling MS extensions should allow us to add BAR definitions.
+// RUN: %clang_cc1 -fms-extensions -DFOO %S/variables.h -emit-pch -o %t1.pch
+// RUN: %clang_cc1 -fms-extensions -include-pch %t1.pch -DBAR=int -pch-through-header=%S/variables.h -verify %s 2> %t.err
+
+#include "variables.h"
+
+BAR bar = 17;
+#ifndef _MSC_EXTENSIONS
+// expected-error@-2 {{unknown type name 'BAR'}}
+#endif
+
+#ifndef FOO
+# error FOO was not defined
+#endif
+
+#if FOO != 1
+# error FOO has the wrong definition
+#endif
+
+#if defined(_MSC_EXTENSIONS) && !defined(BAR)
+# error BAR was not defined
+#endif
+
+// CHECK-FOO: definition of macro 'FOO' differs between the precompiled header ('1') and the command line ('blah')
+// CHECK-NOFOO: macro 'FOO' was defined in the precompiled header but undef'd on the command line
+
+// expected-warning@1 {{definition of macro 'BAR' does not match definition in precompiled header}}