Improve the -Wsign-compare heuristics:

  * If the unsigned type is smaller than the signed type, never warn, because
    its value will not change when zero-extended to the larger type.
  * If we're testing for (in)equality, and the unsigned value is an integer
    constant whose sign bit is not set, never warn, because even though the
    signed value might change, it can't affect the result of the equality.

Also make the comparison test cases much more rigorous, and have them expose
the subtle differences between C and C++ here.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@86242 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 188 insertions, 17 deletions

diff --git a/test/Sema/compare.c b/test/Sema/compare.c
index 45a100be1e..9d7168d179 100644
--- a/test/Sema/compare.c
+++ b/test/Sema/compare.c
@@ -8,23 +8,194 @@ int test(char *C) { // nothing here should warn.
 }
 
 int ints(long a, unsigned long b) {
-  return (a == b) +        // expected-warning {{comparison of integers of different signs}}
-         ((int)a == b) +   // expected-warning {{comparison of integers of different signs}}
-         ((short)a == b) + // expected-warning {{comparison of integers of different signs}}
-         (a == (unsigned int) b) +  // expected-warning {{comparison of integers of different signs}}
-         (a == (unsigned short) b); // expected-warning {{comparison of integers of different signs}}
-
-  enum Enum {B};
-  return (a == B) +
-         ((int)a == B) +
-         ((short)a == B) +
-         (a == (unsigned int) B) +  // expected-warning {{comparison of integers of different signs}}
-         (a == (unsigned short) B); // expected-warning {{comparison of integers of different signs}}         
-
-  // Should be able to prove all of these are non-negative.
-  return (b == (long) B) +
-         (b == (int) B) +
-         (b == (short) B);
+  enum EnumA {A};
+  enum EnumB {B};
+  enum EnumC {C = 0x10000};
+  return
+         // (a,b)
+         (a == (unsigned long) b) +  // expected-warning {{comparison of integers of different signs}}
+         (a == (unsigned int) b) +
+         (a == (unsigned short) b) +
+         (a == (unsigned char) b) +
+         ((long) a == b) +  // expected-warning {{comparison of integers of different signs}}
+         ((int) a == b) +  // expected-warning {{comparison of integers of different signs}}
+         ((short) a == b) +  // expected-warning {{comparison of integers of different signs}}
+         ((signed char) a == b) +  // expected-warning {{comparison of integers of different signs}}
+         ((long) a == (unsigned long) b) +  // expected-warning {{comparison of integers of different signs}}
+         ((int) a == (unsigned int) b) +  // expected-warning {{comparison of integers of different signs}}
+         ((short) a == (unsigned short) b) +  // expected-warning {{comparison of integers of different signs}}
+         ((signed char) a == (unsigned char) b) +  // expected-warning {{comparison of integers of different signs}}
+         (a < (unsigned long) b) +  // expected-warning {{comparison of integers of different signs}}
+         (a < (unsigned int) b) +
+         (a < (unsigned short) b) +
+         (a < (unsigned char) b) +
+         ((long) a < b) +  // expected-warning {{comparison of integers of different signs}}
+         ((int) a < b) +  // expected-warning {{comparison of integers of different signs}}
+         ((short) a < b) +  // expected-warning {{comparison of integers of different signs}}
+         ((signed char) a < b) +  // expected-warning {{comparison of integers of different signs}}
+         ((long) a < (unsigned long) b) +  // expected-warning {{comparison of integers of different signs}}
+         ((int) a < (unsigned int) b) +  // expected-warning {{comparison of integers of different signs}}
+         ((short) a < (unsigned short) b) +  // expected-warning {{comparison of integers of different signs}}
+         ((signed char) a < (unsigned char) b) +  // expected-warning {{comparison of integers of different signs}}
+
+         // (A,b)
+         (A == (unsigned long) b) +
+         (A == (unsigned int) b) +
+         (A == (unsigned short) b) +
+         (A == (unsigned char) b) +
+         ((long) A == b) +
+         ((int) A == b) +
+         ((short) A == b) +
+         ((signed char) A == b) +
+         ((long) A == (unsigned long) b) +
+         ((int) A == (unsigned int) b) +
+         ((short) A == (unsigned short) b) +
+         ((signed char) A == (unsigned char) b) +
+         (A < (unsigned long) b) +
+         (A < (unsigned int) b) +
+         (A < (unsigned short) b) +
+         (A < (unsigned char) b) +
+         ((long) A < b) +
+         ((int) A < b) +
+         ((short) A < b) +
+         ((signed char) A < b) +
+         ((long) A < (unsigned long) b) +
+         ((int) A < (unsigned int) b) +
+         ((short) A < (unsigned short) b) +
+         ((signed char) A < (unsigned char) b) +
+
+         // (a,B)
+         (a == (unsigned long) B) +
+         (a == (unsigned int) B) +
+         (a == (unsigned short) B) +
+         (a == (unsigned char) B) +
+         ((long) a == B) +
+         ((int) a == B) +
+         ((short) a == B) +
+         ((signed char) a == B) +
+         ((long) a == (unsigned long) B) +
+         ((int) a == (unsigned int) B) +
+         ((short) a == (unsigned short) B) +
+         ((signed char) a == (unsigned char) B) +
+         (a < (unsigned long) B) +  // expected-warning {{comparison of integers of different signs}}
+         (a < (unsigned int) B) +
+         (a < (unsigned short) B) +
+         (a < (unsigned char) B) +
+         ((long) a < B) +
+         ((int) a < B) +
+         ((short) a < B) +
+         ((signed char) a < B) +
+         ((long) a < (unsigned long) B) +  // expected-warning {{comparison of integers of different signs}}
+         ((int) a < (unsigned int) B) +  // expected-warning {{comparison of integers of different signs}}
+         ((short) a < (unsigned short) B) +  // expected-warning {{comparison of integers of different signs}}
+         ((signed char) a < (unsigned char) B) +  // expected-warning {{comparison of integers of different signs}}
+
+         // (C,b)
+         (C == (unsigned long) b) +
+         (C == (unsigned int) b) +
+         (C == (unsigned short) b) +
+         (C == (unsigned char) b) +
+         ((long) C == b) +
+         ((int) C == b) +
+         ((short) C == b) +
+         ((signed char) C == b) +
+         ((long) C == (unsigned long) b) +
+         ((int) C == (unsigned int) b) +
+         ((short) C == (unsigned short) b) +
+         ((signed char) C == (unsigned char) b) +
+         (C < (unsigned long) b) +
+         (C < (unsigned int) b) +
+         (C < (unsigned short) b) +
+         (C < (unsigned char) b) +
+         ((long) C < b) +
+         ((int) C < b) +
+         ((short) C < b) +
+         ((signed char) C < b) +
+         ((long) C < (unsigned long) b) +
+         ((int) C < (unsigned int) b) +
+         ((short) C < (unsigned short) b) +
+         ((signed char) C < (unsigned char) b) +
+
+         // (a,C)
+         (a == (unsigned long) C) +
+         (a == (unsigned int) C) +
+         (a == (unsigned short) C) +
+         (a == (unsigned char) C) +
+         ((long) a == C) +
+         ((int) a == C) +
+         ((short) a == C) +
+         ((signed char) a == C) +
+         ((long) a == (unsigned long) C) +
+         ((int) a == (unsigned int) C) +
+         ((short) a == (unsigned short) C) +
+         ((signed char) a == (unsigned char) C) +
+         (a < (unsigned long) C) +  // expected-warning {{comparison of integers of different signs}}
+         (a < (unsigned int) C) +
+         (a < (unsigned short) C) +
+         (a < (unsigned char) C) +
+         ((long) a < C) +
+         ((int) a < C) +
+         ((short) a < C) +
+         ((signed char) a < C) +
+         ((long) a < (unsigned long) C) +  // expected-warning {{comparison of integers of different signs}}
+         ((int) a < (unsigned int) C) +  // expected-warning {{comparison of integers of different signs}}
+         ((short) a < (unsigned short) C) +  // expected-warning {{comparison of integers of different signs}}
+         ((signed char) a < (unsigned char) C) +  // expected-warning {{comparison of integers of different signs}}
+
+         // (0x80000,b)
+         (0x80000 == (unsigned long) b) +
+         (0x80000 == (unsigned int) b) +
+         (0x80000 == (unsigned short) b) +
+         (0x80000 == (unsigned char) b) +
+         ((long) 0x80000 == b) +
+         ((int) 0x80000 == b) +
+         ((short) 0x80000 == b) +
+         ((signed char) 0x80000 == b) +
+         ((long) 0x80000 == (unsigned long) b) +
+         ((int) 0x80000 == (unsigned int) b) +
+         ((short) 0x80000 == (unsigned short) b) +
+         ((signed char) 0x80000 == (unsigned char) b) +
+         (0x80000 < (unsigned long) b) +
+         (0x80000 < (unsigned int) b) +
+         (0x80000 < (unsigned short) b) +
+         (0x80000 < (unsigned char) b) +
+         ((long) 0x80000 < b) +
+         ((int) 0x80000 < b) +
+         ((short) 0x80000 < b) +
+         ((signed char) 0x80000 < b) +
+         ((long) 0x80000 < (unsigned long) b) +
+         ((int) 0x80000 < (unsigned int) b) +
+         ((short) 0x80000 < (unsigned short) b) +
+         ((signed char) 0x80000 < (unsigned char) b) +
+
+         // (a,0x80000)
+         (a == (unsigned long) 0x80000) +
+         (a == (unsigned int) 0x80000) +
+         (a == (unsigned short) 0x80000) +
+         (a == (unsigned char) 0x80000) +
+         ((long) a == 0x80000) +
+         ((int) a == 0x80000) +
+         ((short) a == 0x80000) +
+         ((signed char) a == 0x80000) +
+         ((long) a == (unsigned long) 0x80000) +
+         ((int) a == (unsigned int) 0x80000) +
+         ((short) a == (unsigned short) 0x80000) +
+         ((signed char) a == (unsigned char) 0x80000) +
+         (a < (unsigned long) 0x80000) +  // expected-warning {{comparison of integers of different signs}}
+         (a < (unsigned int) 0x80000) +
+         (a < (unsigned short) 0x80000) +
+         (a < (unsigned char) 0x80000) +
+         ((long) a < 0x80000) +
+         ((int) a < 0x80000) +
+         ((short) a < 0x80000) +
+         ((signed char) a < 0x80000) +
+         ((long) a < (unsigned long) 0x80000) +  // expected-warning {{comparison of integers of different signs}}
+         ((int) a < (unsigned int) 0x80000) +  // expected-warning {{comparison of integers of different signs}}
+         ((short) a < (unsigned short) 0x80000) +  // expected-warning {{comparison of integers of different signs}}
+         ((signed char) a < (unsigned char) 0x80000) +  // expected-warning {{comparison of integers of different signs}}
+
+         10
+    ;
 }
 
 int equal(char *a, const char *b) {