Loosen -Wempty-body warning

Do not show it when `if` or `else` come from macros.
E.g.,

    #define USED(A) if (A); else
    #define SOME_IF(A) if (A)

    void test() {
      // No warnings are shown in those cases now.
      USED(0);
      SOME_IF(0);
    }

Patch by Ilya Biryukov!

Differential Revision: https://reviews.llvm.org/D40185

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@318556 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 11 insertions, 0 deletions

diff --git a/test/SemaCXX/warn-empty-body.cpp b/test/SemaCXX/warn-empty-body.cpp
index bd6b47f053..0fc0cd51f9 100644
--- a/test/SemaCXX/warn-empty-body.cpp
+++ b/test/SemaCXX/warn-empty-body.cpp
@@ -301,3 +301,14 @@ void test7(int x, int y) {
   if (x) IDENTITY(); // no-warning
 }
 
+#define SOME_IF(A) if (A)
+#define IF_ELSE(A) if (A); else
+
+
+void test_macros() {
+  SOME_IF(0);
+  IF_ELSE(0);
+
+  IDENTITY(if (0);) // expected-warning{{if statement has empty body}} expected-note{{separate line}}
+  IDENTITY(if (0); else;) // expected-warning{{else clause has empty body}} expected-note{{separate line}}}
+}