mgrabovsky updated this revision to Diff 37720.
mgrabovsky added a comment.
Change message wording
http://reviews.llvm.org/D13643
Files:
include/clang/Basic/DiagnosticSemaKinds.td
lib/Sema/SemaChecking.cpp
test/Sema/bool-compare.c
Index: test/Sema/bool-compare.c
===================================================================
--- test/Sema/bool-compare.c
+++ test/Sema/bool-compare.c
@@ -85,7 +85,9 @@
if ((a<y) != -1) {}// expected-warning {{comparison of constant -1 with boolean expression is always true}}
if ((a<y) == z) {} // no warning
- if (a>y<z) {} // no warning
+ if (a>y<z) {} // expected-warning {{comparisons such as 'a > b < c' do not have their mathematical meaning}} \
+ // expected-note {{to achieve the expected behavior, turn this expression into a conjunction of two comparisons}} \
+ // expected-note {{place parentheses around either of the comparisons to silence this warning}}
if ((a<y) > z) {} // no warning
if((a<y)>(z<y)) {} // no warning
if((a<y)==(z<y)){} // no warning
@@ -144,10 +146,18 @@
if (z !=(a<y)) {} // no warning
if (-1 !=(a<y)) {} // expected-warning {{comparison of constant -1 with boolean expression is always true}}
- if (z ==(a<y)) {} // no warning
- if (z<a>y) {} // no warning
- if (z > (a<y)) {} // no warning
- if((z<y)>(a<y)) {} // no warning
+ if (a == b == z) {} // expected-warning {{comparisons such as 'a == b == c' do not have their mathematical meaning}} \
+ // expected-note {{to achieve the expected behavior, turn this expression into a conjunction of two comparisons}} \
+ // expected-note {{place parentheses around either of the comparisons to silence this warning}}
+ if ((a==y)==z) {} // no warning
+ if (a==(y==z)) {} // no warning
+
+ if (z ==(a<y)) {} // no warning
+ if (z<a>y) {} // expected-warning {{comparisons such as 'a < b > c' do not have their mathematical meaning}} \
+ // expected-note {{to achieve the expected behavior, turn this expression into a conjunction of two comparisons}} \
+ // expected-note {{place parentheses around either of the comparisons to silence this warning}}
+ if (z > (a<y)) {} // no warning
+ if((z<y)>(a<y)) {} // no warning
if((z<y)==(a<y)){} // no warning
if((z<y)!=(a<y)){} // no warning
if((y==z)<(z==x)){} // no warning
Index: lib/Sema/SemaChecking.cpp
===================================================================
--- lib/Sema/SemaChecking.cpp
+++ lib/Sema/SemaChecking.cpp
@@ -6693,6 +6693,24 @@
<< E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange());
}
+/// Diagnose attempts at ternary comparison, e.g., 1 < x < 2
+static void DiagnoseTernaryComparison(Sema &S, BinaryOperator *E) {
+ BinaryOperator *LHS = dyn_cast<BinaryOperator>(E->getLHS());
+ if (!LHS || !LHS->isComparisonOp())
+ return;
+
+ SourceLocation Loc = E->getSourceRange().getBegin();
+
+ S.Diag(Loc, diag::warn_ternary_comparison)
+ << LHS->getOpcodeStr()
+ << E->getOpcodeStr()
+ << E->getSourceRange();
+ S.Diag(Loc, diag::note_ternary_comparison_to_conjunction);
+ S.Diag(Loc, diag::note_ternary_comparison_silence)
+ << FixItHint::CreateInsertion(LHS->getSourceRange().getBegin(), "(")
+ << FixItHint::CreateInsertion(LHS->getSourceRange().getEnd(), ")");
+}
+
/// Analyze the operands of the given comparison. Implements the
/// fallback case from AnalyzeComparison.
static void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) {
@@ -6716,11 +6734,13 @@
if (E->isValueDependent())
return AnalyzeImpConvsInComparison(S, E);
+ DiagnoseTernaryComparison(S, E);
+
Expr *LHS = E->getLHS()->IgnoreParenImpCasts();
Expr *RHS = E->getRHS()->IgnoreParenImpCasts();
-
+
bool IsComparisonConstant = false;
-
+
// Check whether an integer constant comparison results in a value
// of 'true' or 'false'.
if (T->isIntegralType(S.Context)) {
Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -5866,6 +5866,14 @@
def note_condition_assign_silence : Note<
"place parentheses around the assignment to silence this warning">;
+def warn_ternary_comparison : Warning<"comparisons such as 'a %0 b %1 c' do not "
+ "have their mathematical meaning">,
+ InGroup<Parentheses>;
+def note_ternary_comparison_to_conjunction : Note<"to achieve the expected behavior, "
+ "turn this expression into a conjunction of two comparisons">;
+def note_ternary_comparison_silence : Note<"place parentheses around either "
+ "of the comparisons to silence this warning">;
+
def warn_equality_with_extra_parens : Warning<"equality comparison with "
"extraneous parentheses">, InGroup<ParenthesesOnEquality>;
def note_equality_comparison_to_assign : Note<
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