Enhance -Wtautological-constant-out-of-range-compare to include the name of the enum constant.

This is QoI.  Fixes <rdar://problem/13076064>.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177190 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Sema/SemaChecking.cpp

@@ -4495,9 +4495,22 @@ static void DiagnoseOutOfRangeComparison(Sema &S, BinaryOperator *E,
     else // op == BO_GT || op == BO_GE
       IsTrue = PositiveConstant;
   }
-  SmallString<16> PrettySourceValue(Value.toString(10));
+
+  // If this is a comparison to an enum constant, include that
+  // constant in the diagnostic.
+  const EnumConstantDecl *ED = 0;
+  if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Constant))
+    ED = dyn_cast<EnumConstantDecl>(DR->getDecl());
+
+  SmallString<64> PrettySourceValue;
+  llvm::raw_svector_ostream OS(PrettySourceValue);
+  if (ED)
+    OS << '\'' << ED->getName() << "' (" << Value << ")";
+  else
+    OS << Value;
+
   S.Diag(E->getOperatorLoc(), diag::warn_out_of_range_compare)
-      << PrettySourceValue << OtherT << IsTrue
+      << OS.str() << OtherT << IsTrue
       << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
 }
 

test/Sema/compare.c

@@ -93,8 +93,8 @@ int ints(long a, unsigned long b) {
          // (C,b)
          (C == (unsigned long) b) +
          (C == (unsigned int) b) +
-         (C == (unsigned short) b) + // expected-warning {{comparison of constant 65536 with expression of type 'unsigned short' is always false}}
-         (C == (unsigned char) b) + // expected-warning {{comparison of constant 65536 with expression of type 'unsigned char' is always false}}
+         (C == (unsigned short) b) + // expected-warning {{comparison of constant 'C' (65536) with expression of type 'unsigned short' is always false}}
+         (C == (unsigned char) b) + // expected-warning {{comparison of constant 'C' (65536) with expression of type 'unsigned char' is always false}}
          ((long) C == b) +
          ((int) C == b) +
          ((short) C == b) +
@@ -105,8 +105,8 @@ int ints(long a, unsigned long b) {
          ((signed char) C == (unsigned char) b) +
          (C < (unsigned long) b) +
          (C < (unsigned int) b) +
-         (C < (unsigned short) b) + // expected-warning {{comparison of constant 65536 with expression of type 'unsigned short' is always false}}
-         (C < (unsigned char) b) + // expected-warning {{comparison of constant 65536 with expression of type 'unsigned char' is always false}}
+         (C < (unsigned short) b) + // expected-warning {{comparison of constant 'C' (65536) with expression of type 'unsigned short' is always false}}
+         (C < (unsigned char) b) + // expected-warning {{comparison of constant 'C' (65536) with expression of type 'unsigned char' is always false}}
          ((long) C < b) +
          ((int) C < b) +
          ((short) C < b) +
@@ -123,8 +123,8 @@ int ints(long a, unsigned long b) {
          (a == (unsigned char) C) +
          ((long) a == C) +
          ((int) a == C) +
-         ((short) a == C) + // expected-warning {{comparison of constant 65536 with expression of type 'short' is always false}}
-         ((signed char) a == C) + // expected-warning {{comparison of constant 65536 with expression of type 'signed char' is always false}}
+         ((short) a == C) + // expected-warning {{comparison of constant 'C' (65536) with expression of type 'short' is always false}}
+         ((signed char) a == C) + // expected-warning {{comparison of constant 'C' (65536) with expression of type 'signed char' is always false}}
          ((long) a == (unsigned long) C) +
          ((int) a == (unsigned int) C) +
          ((short) a == (unsigned short) C) +
@@ -135,8 +135,8 @@ int ints(long a, unsigned long b) {
          (a < (unsigned char) C) +
          ((long) a < C) +
          ((int) a < C) +
-         ((short) a < C) + // expected-warning {{comparison of constant 65536 with expression of type 'short' is always true}}
-         ((signed char) a < C) + // expected-warning {{comparison of constant 65536 with expression of type 'signed char' is always true}}
+         ((short) a < C) + // expected-warning {{comparison of constant 'C' (65536) with expression of type 'short' is always true}}
+         ((signed char) a < C) + // expected-warning {{comparison of constant 'C' (65536) with expression of type 'signed char' is always true}}
          ((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) +

test/SemaCXX/compare.cpp

@@ -89,8 +89,8 @@ int test0(long a, unsigned long b) {
          // (C,b)
          (C == (unsigned long) b) +
          (C == (unsigned int) b) +
-         (C == (unsigned short) b) + // expected-warning {{comparison of constant 65536 with expression of type 'unsigned short' is always false}}
-         (C == (unsigned char) b) +  // expected-warning {{comparison of constant 65536 with expression of type 'unsigned char' is always false}}
+         (C == (unsigned short) b) + // expected-warning {{comparison of constant 'C' (65536) with expression of type 'unsigned short' is always false}}
+         (C == (unsigned char) b) +  // expected-warning {{comparison of constant 'C' (65536) with expression of type 'unsigned char' is always false}}
          ((long) C == b) +
          ((int) C == b) +
          ((short) C == b) +
@@ -101,8 +101,8 @@ int test0(long a, unsigned long b) {
          ((signed char) C == (unsigned char) b) +
          (C < (unsigned long) b) +
          (C < (unsigned int) b) +
-         (C < (unsigned short) b) + // expected-warning {{comparison of constant 65536 with expression of type 'unsigned short' is always false}}
-         (C < (unsigned char) b) + // expected-warning {{comparison of constant 65536 with expression of type 'unsigned char' is always false}}
+         (C < (unsigned short) b) + // expected-warning {{comparison of constant 'C' (65536) with expression of type 'unsigned short' is always false}}
+         (C < (unsigned char) b) + // expected-warning {{comparison of constant 'C' (65536) with expression of type 'unsigned char' is always false}}
          ((long) C < b) +
          ((int) C < b) +
          ((short) C < b) +
@@ -119,8 +119,8 @@ int test0(long a, unsigned long b) {
          (a == (unsigned char) C) +
          ((long) a == C) +
          ((int) a == C) +
-         ((short) a == C) + // expected-warning {{comparison of constant 65536 with expression of type 'short' is always false}}
-         ((signed char) a == C) + // expected-warning {{comparison of constant 65536 with expression of type 'signed char' is always false}}
+         ((short) a == C) + // expected-warning {{comparison of constant 'C' (65536) with expression of type 'short' is always false}}
+         ((signed char) a == C) + // expected-warning {{comparison of constant 'C' (65536) with expression of type 'signed char' is always false}}
          ((long) a == (unsigned long) C) +
          ((int) a == (unsigned int) C) +
          ((short) a == (unsigned short) C) +
@@ -131,8 +131,8 @@ int test0(long a, unsigned long b) {
          (a < (unsigned char) C) +
          ((long) a < C) +
          ((int) a < C) +
-         ((short) a < C) + // expected-warning {{comparison of constant 65536 with expression of type 'short' is always true}}
-         ((signed char) a < C) + // expected-warning {{comparison of constant 65536 with expression of type 'signed char' is always true}}
+         ((short) a < C) + // expected-warning {{comparison of constant 'C' (65536) with expression of type 'short' is always true}}
+         ((signed char) a < C) + // expected-warning {{comparison of constant 'C' (65536) with expression of type 'signed char' is always true}}
          ((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) +

test/SemaCXX/warn-enum-compare.cpp

@@ -39,8 +39,8 @@ void test () {
   while (b == c);
   while (B1 == name1::B2);
   while (B2 == name2::B1);
-  while (x == AnonAA); // expected-warning {{comparison of constant 42 with expression of type 'Foo' is always false}}
-  while (AnonBB == y); // expected-warning {{comparison of constant 45 with expression of type 'Bar' is always false}}
+  while (x == AnonAA); // expected-warning {{comparison of constant 'AnonAA' (42) with expression of type 'Foo' is always false}}
+  while (AnonBB == y); // expected-warning {{comparison of constant 'AnonBB' (45) with expression of type 'Bar' is always false}}
   while (AnonAA == AnonAB);
   while (AnonAB == AnonBA);
   while (AnonBB == AnonAA);