Author: xbolva00
Date: Sun Sep 22 15:00:48 2019
New Revision: 372531
URL: http://llvm.org/viewvc/llvm-project?rev=372531&view=rev
Log:
[Diagnostics] Warn if ?: with integer constants always evaluates to true
Extracted from D63082. GCC has this warning under -Wint-in-bool-context, but as
noted in the D63082's review, we should put it under
TautologicalConstantCompare.
Added:
cfe/trunk/test/Sema/warn-integer-constants-in-ternary.c
Modified:
cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
cfe/trunk/lib/Sema/SemaChecking.cpp
Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=372531&r1=372530&r2=372531&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
+++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Sun Sep 22 15:00:48
2019
@@ -6137,6 +6137,10 @@ def warn_out_of_range_compare : Warning<
InGroup<TautologicalOutOfRangeCompare>;
def warn_tautological_bool_compare : Warning<warn_out_of_range_compare.Text>,
InGroup<TautologicalConstantCompare>;
+def warn_integer_constants_in_conditional_always_true : Warning<
+ "converting the result of '?:' with integer constants to a boolean always "
+ "evaluates to 'true'">,
+ InGroup<TautologicalConstantCompare>;
def warn_comparison_of_mixed_enum_types : Warning<
"comparison of two values with different enumeration types"
"%diff{ ($ and $)|}0,1">,
Modified: cfe/trunk/lib/Sema/SemaChecking.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaChecking.cpp?rev=372531&r1=372530&r2=372531&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaChecking.cpp (original)
+++ cfe/trunk/lib/Sema/SemaChecking.cpp Sun Sep 22 15:00:48 2019
@@ -11256,6 +11256,44 @@ static bool isSameWidthConstantConversio
return true;
}
+static void DiagnoseIntInBoolContext(Sema &S, const Expr *E) {
+ E = E->IgnoreParenImpCasts();
+ SourceLocation ExprLoc = E->getExprLoc();
+
+ if (const auto *CO = dyn_cast<ConditionalOperator>(E)) {
+ const auto *LHS = dyn_cast<IntegerLiteral>(CO->getTrueExpr());
+ if (!LHS) {
+ if (auto *UO = dyn_cast<UnaryOperator>(CO->getTrueExpr())) {
+ if (UO->getOpcode() == UO_Minus)
+ LHS = dyn_cast<IntegerLiteral>(UO->getSubExpr());
+ if (!LHS)
+ return;
+ } else {
+ return;
+ }
+ }
+
+ const auto *RHS = dyn_cast<IntegerLiteral>(CO->getFalseExpr());
+ if (!RHS) {
+ if (auto *UO = dyn_cast<UnaryOperator>(CO->getFalseExpr())) {
+ if (UO->getOpcode() == UO_Minus)
+ RHS = dyn_cast<IntegerLiteral>(UO->getSubExpr());
+ if (!RHS)
+ return;
+ } else {
+ return;
+ }
+ }
+
+ if ((LHS->getValue() == 0 || LHS->getValue() == 1) &&
+ (RHS->getValue() == 0 || RHS->getValue() == 1))
+ // Do not diagnose common idioms
+ return;
+ if (LHS->getValue() != 0 && LHS->getValue() != 0)
+ S.Diag(ExprLoc, diag::warn_integer_constants_in_conditional_always_true);
+ }
+}
+
static void CheckImplicitConversion(Sema &S, Expr *E, QualType T,
SourceLocation CC,
bool *ICContext = nullptr,
@@ -11708,6 +11746,9 @@ static void CheckConditionalOperator(Sem
CheckConditionalOperand(S, E->getTrueExpr(), T, CC, Suspicious);
CheckConditionalOperand(S, E->getFalseExpr(), T, CC, Suspicious);
+ if (T->isBooleanType())
+ DiagnoseIntInBoolContext(S, E);
+
// If -Wconversion would have warned about either of the candidates
// for a signedness conversion to the context type...
if (!Suspicious) return;
Added: cfe/trunk/test/Sema/warn-integer-constants-in-ternary.c
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/warn-integer-constants-in-ternary.c?rev=372531&view=auto
==============================================================================
--- cfe/trunk/test/Sema/warn-integer-constants-in-ternary.c (added)
+++ cfe/trunk/test/Sema/warn-integer-constants-in-ternary.c Sun Sep 22 15:00:48
2019
@@ -0,0 +1,32 @@
+// RUN: %clang_cc1 -x c -fsyntax-only -verify -Wtautological-constant-compare
%s
+// RUN: %clang_cc1 -x c -fsyntax-only -verify %s
+// RUN: %clang_cc1 -x c++ -fsyntax-only -verify
-Wtautological-constant-compare %s
+// RUN: %clang_cc1 -x c++ -fsyntax-only -verify %s
+
+#define ONE 1
+#define TWO 2
+
+#define TERN(c, l, r) c ? l : r
+
+#ifdef __cplusplus
+typedef bool boolean;
+#else
+typedef _Bool boolean;
+#endif
+
+void test(boolean a) {
+ boolean r;
+ r = a ? (1) : TWO;
+ r = a ? 3 : TWO; // expected-warning {{converting the result of '?:' with
integer constants to a boolean always evaluates to 'true'}}
+ r = a ? -2 : 0; // expected-warning {{converting the result of '?:' with
integer constants to a boolean always evaluates to 'true'}}
+ r = a ? 3 : -2; // expected-warning {{converting the result of '?:' with
integer constants to a boolean always evaluates to 'true'}}
+ r = a ? 0 : TWO;
+ r = a ? 3 : ONE; // expected-warning {{converting the result of '?:' with
integer constants to a boolean always evaluates to 'true'}}
+ r = a ? ONE : 0;
+ r = a ? 0 : -0;
+ r = a ? 1 : 0;
+ r = a ? ONE : 0;
+ r = a ? ONE : ONE;
+ r = TERN(a, 4, 8); // expected-warning {{converting the result of '?:'
with integer constants to a boolean always evaluates to 'true'}}
+ r = TERN(a, -1, -8); // expected-warning {{converting the result of '?:'
with integer constants to a boolean always evaluates to 'true'}}
+}
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