Teach -Wtautological-overlap-compare about enums

Prior to this patch, -Wtautological-overlap-compare would only warn us
if there was a sketchy logical comparison between variables and
IntegerLiterals. This patch makes -Wtautological-overlap-compare aware
of EnumConstantDecls, so it can apply the same logic to them.

llvm-svn: 249053

1 files changed, 34 insertions, 0 deletions

diff --git a/clang/test/Sema/warn-overlap.c b/clang/test/Sema/warn-overlap.c
index 44d6ad5efa5..1e8a614d0ff 100644
--- a/clang/test/Sema/warn-overlap.c
+++ b/clang/test/Sema/warn-overlap.c
@@ -2,6 +2,16 @@
 
 #define mydefine 2
 
+enum Choices {
+  CHOICE_0 = 0,
+  CHOICE_1 = 1
+};
+
+enum Unchoices {
+  UNCHOICE_0 = 0,
+  UNCHOICE_1 = 1
+};
+
 void f(int x) {
   int y = 0;
 
@@ -54,6 +64,30 @@ void f(int x) {
 
   if (x == mydefine && x > 3) { }
   if (x == (mydefine + 1) && x > 3) { }
+
+  if (x != CHOICE_0 || x != CHOICE_1) { } // expected-warning {{overlapping comparisons always evaluate to true}}
+  if (x == CHOICE_0 && x == CHOICE_1) { } // expected-warning {{overlapping comparisons always evaluate to false}}
+
+  // Don't warn if comparing x to different types
+  if (x == CHOICE_0 && x == 1) { }
+  if (x != CHOICE_0 || x != 1) { }
+
+  // "Different types" includes different enums
+  if (x == CHOICE_0 && x == UNCHOICE_1) { }
+  if (x != CHOICE_0 || x != UNCHOICE_1) { }
+}
+
+void enums(enum Choices c) {
+  if (c != CHOICE_0 || c != CHOICE_1) { } // expected-warning {{overlapping comparisons always evaluate to true}}
+  if (c == CHOICE_0 && c == CHOICE_1) { } // expected-warning {{overlapping comparisons always evaluate to false}}
+
+  // Don't warn if comparing x to different types
+  if (c == CHOICE_0 && c == 1) { }
+  if (c != CHOICE_0 || c != 1) { }
+
+  // "Different types" includes different enums
+  if (c == CHOICE_0 && c == UNCHOICE_1) { }
+  if (c != CHOICE_0 || c != UNCHOICE_1) { }
 }
 
 // Don't generate a warning here.