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-rw-r--r--clang/include/clang/Basic/DiagnosticSemaKinds.td2
-rw-r--r--clang/lib/Sema/SemaExpr.cpp85
-rw-r--r--clang/test/Sema/exprs.c2
-rw-r--r--clang/test/Sema/warn-stringcompare.c29
4 files changed, 76 insertions, 42 deletions
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 6e4b60181d9..c19862addec 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -8428,7 +8428,7 @@ def warn_tautological_overlap_comparison : Warning<
def warn_stringcompare : Warning<
"result of comparison against %select{a string literal|@encode}0 is "
- "unspecified (use strncmp instead)">,
+ "unspecified (use an explicit string comparison function instead)">,
InGroup<StringCompare>;
def warn_identity_field_assign : Warning<
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 3be8af1dd9e..7bbda127a54 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -10338,7 +10338,6 @@ static void diagnoseTautologicalComparison(Sema &S, SourceLocation Loc,
QualType RHSType = RHS->getType();
if (LHSType->hasFloatingRepresentation() ||
(LHSType->isBlockPointerType() && !BinaryOperator::isEqualityOp(Opc)) ||
- LHS->getBeginLoc().isMacroID() || RHS->getBeginLoc().isMacroID() ||
S.inTemplateInstantiation())
return;
@@ -10366,45 +10365,51 @@ static void diagnoseTautologicalComparison(Sema &S, SourceLocation Loc,
AlwaysEqual, // std::strong_ordering::equal from operator<=>
};
- if (Expr::isSameComparisonOperand(LHS, RHS)) {
- unsigned Result;
- switch (Opc) {
- case BO_EQ: case BO_LE: case BO_GE:
- Result = AlwaysTrue;
- break;
- case BO_NE: case BO_LT: case BO_GT:
- Result = AlwaysFalse;
- break;
- case BO_Cmp:
- Result = AlwaysEqual;
- break;
- default:
- Result = AlwaysConstant;
- break;
- }
- S.DiagRuntimeBehavior(Loc, nullptr,
- S.PDiag(diag::warn_comparison_always)
- << 0 /*self-comparison*/
- << Result);
- } else if (checkForArray(LHSStripped) && checkForArray(RHSStripped)) {
- // What is it always going to evaluate to?
- unsigned Result;
- switch(Opc) {
- case BO_EQ: // e.g. array1 == array2
- Result = AlwaysFalse;
- break;
- case BO_NE: // e.g. array1 != array2
- Result = AlwaysTrue;
- break;
- default: // e.g. array1 <= array2
- // The best we can say is 'a constant'
- Result = AlwaysConstant;
- break;
+ if (!LHS->getBeginLoc().isMacroID() && !RHS->getBeginLoc().isMacroID()) {
+ if (Expr::isSameComparisonOperand(LHS, RHS)) {
+ unsigned Result;
+ switch (Opc) {
+ case BO_EQ:
+ case BO_LE:
+ case BO_GE:
+ Result = AlwaysTrue;
+ break;
+ case BO_NE:
+ case BO_LT:
+ case BO_GT:
+ Result = AlwaysFalse;
+ break;
+ case BO_Cmp:
+ Result = AlwaysEqual;
+ break;
+ default:
+ Result = AlwaysConstant;
+ break;
+ }
+ S.DiagRuntimeBehavior(Loc, nullptr,
+ S.PDiag(diag::warn_comparison_always)
+ << 0 /*self-comparison*/
+ << Result);
+ } else if (checkForArray(LHSStripped) && checkForArray(RHSStripped)) {
+ // What is it always going to evaluate to?
+ unsigned Result;
+ switch (Opc) {
+ case BO_EQ: // e.g. array1 == array2
+ Result = AlwaysFalse;
+ break;
+ case BO_NE: // e.g. array1 != array2
+ Result = AlwaysTrue;
+ break;
+ default: // e.g. array1 <= array2
+ // The best we can say is 'a constant'
+ Result = AlwaysConstant;
+ break;
+ }
+ S.DiagRuntimeBehavior(Loc, nullptr,
+ S.PDiag(diag::warn_comparison_always)
+ << 1 /*array comparison*/
+ << Result);
}
- S.DiagRuntimeBehavior(Loc, nullptr,
- S.PDiag(diag::warn_comparison_always)
- << 1 /*array comparison*/
- << Result);
}
if (isa<CastExpr>(LHSStripped))
@@ -10413,7 +10418,7 @@ static void diagnoseTautologicalComparison(Sema &S, SourceLocation Loc,
RHSStripped = RHSStripped->IgnoreParenCasts();
// Warn about comparisons against a string constant (unless the other
- // operand is null); the user probably wants strcmp.
+ // operand is null); the user probably wants string comparison function.
Expr *LiteralString = nullptr;
Expr *LiteralStringStripped = nullptr;
if ((isa<StringLiteral>(LHSStripped) || isa<ObjCEncodeExpr>(LHSStripped)) &&
diff --git a/clang/test/Sema/exprs.c b/clang/test/Sema/exprs.c
index dbe61ad8ac6..760c45e02f3 100644
--- a/clang/test/Sema/exprs.c
+++ b/clang/test/Sema/exprs.c
@@ -119,7 +119,7 @@ void test11(struct mystruct P, float F) {
// PR3753
int test12(const char *X) {
- return X == "foo"; // expected-warning {{comparison against a string literal is unspecified (use strncmp instead)}}
+ return X == "foo"; // expected-warning {{comparison against a string literal is unspecified (use an explicit string comparison function instead)}}
}
int test12b(const char *X) {
diff --git a/clang/test/Sema/warn-stringcompare.c b/clang/test/Sema/warn-stringcompare.c
new file mode 100644
index 00000000000..77876ad6abd
--- /dev/null
+++ b/clang/test/Sema/warn-stringcompare.c
@@ -0,0 +1,29 @@
+// RUN: %clang_cc1 -x c -fsyntax-only -verify %s
+// RUN: %clang_cc1 -x c++ -fsyntax-only -verify %s
+
+#define DELIM "/"
+#define DOT "."
+#define NULL (void *)0
+
+void test(const char *d) {
+ if ("/" != d) // expected-warning {{result of comparison against a string literal is unspecified (use an explicit string comparison function instead)}}
+ return;
+ if (d == "/") // expected-warning {{result of comparison against a string literal is unspecified (use an explicit string comparison function instead)}}
+ return;
+ if ("/" != NULL)
+ return;
+ if (NULL == "/")
+ return;
+ if ("/" != DELIM) // expected-warning {{result of comparison against a string literal is unspecified (use an explicit string comparison function instead)}}
+ return;
+ if (DELIM == "/") // expected-warning {{result of comparison against a string literal is unspecified (use an explicit string comparison function instead)}}
+ return;
+ if (DELIM != NULL)
+ return;
+ if (NULL == DELIM)
+ return;
+ if (DOT != DELIM) // expected-warning {{result of comparison against a string literal is unspecified (use an explicit string comparison function instead)}}
+ return;
+ if (DELIM == DOT) // expected-warning {{result of comparison against a string literal is unspecified (use an explicit string comparison function instead)}}
+ return;
+}
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