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Don't suggest assignment in implausible situation. We still warn, as the 

code is very likely to be buggy, but its going to require more
significant changes on the part of the user to correct it in this case.

llvm-svn: 137820
This commit is contained in:
Chandler Carruth 2011-08-17 08:38:11 +00:00
parent ae51ecc57b
commit e89ca5f7d2
2 changed files with 19 additions and 9 deletions
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24
clang/lib/Sema/SemaStmt.cpp
View File

@ -147,21 +147,23 @@ static void DiagnoseTopLevelComparison(Sema &S, const Stmt *Statement) {
}
SourceLocation Loc;
bool IsNotEqual = false;
bool IsNotEqual, CanAssign;
if (const BinaryOperator *Op = dyn_cast<BinaryOperator>(E)) {
if (Op->getOpcode() != BO_EQ && Op->getOpcode() != BO_NE)
return;
IsNotEqual = Op->getOpcode() == BO_NE;
Loc = Op->getOperatorLoc();
IsNotEqual = Op->getOpcode() == BO_NE;
CanAssign = Op->getLHS()->IgnoreParenImpCasts()->isLValue();
} else if (const CXXOperatorCallExpr *Op = dyn_cast<CXXOperatorCallExpr>(E)) {
if (Op->getOperator() != OO_EqualEqual &&
Op->getOperator() != OO_ExclaimEqual)
return;
IsNotEqual = Op->getOperator() == OO_ExclaimEqual;
Loc = Op->getOperatorLoc();
IsNotEqual = Op->getOperator() == OO_ExclaimEqual;
CanAssign = Op->getArg(0)->IgnoreParenImpCasts()->isLValue();
} else {
// Not a typo-prone comparison.
return;
@ -181,12 +183,16 @@ static void DiagnoseTopLevelComparison(Sema &S, const Stmt *Statement) {
<< FixItHint::CreateInsertion(Open, "(void)(")
<< FixItHint::CreateInsertion(Close, ")");
if (IsNotEqual)
S.Diag(Loc, diag::note_inequality_comparison_to_or_assign)
<< FixItHint::CreateReplacement(Loc, "|=");
else
S.Diag(Loc, diag::note_equality_comparison_to_assign)
<< FixItHint::CreateReplacement(Loc, "=");
// If the LHS is a plausible entity to assign to, provide a fixit hint to
// correct common typos.
if (CanAssign) {
if (IsNotEqual)
S.Diag(Loc, diag::note_inequality_comparison_to_or_assign)
<< FixItHint::CreateReplacement(Loc, "|=");
else
S.Diag(Loc, diag::note_equality_comparison_to_assign)
<< FixItHint::CreateReplacement(Loc, "=");
}
}
void Sema::DiagnoseUnusedExprResult(const Stmt *S) {

4
clang/test/SemaCXX/warn-top-level-comparison.cpp
View File

@ -17,6 +17,8 @@ void test() {
x != 7; // expected-warning {{inequality comparison as an unused top-level statement}} \
// expected-note {{cast this comparison to void to silence this warning}} \
// expected-note {{use '|=' to turn this inequality comparison into an or-assignment}}
7 == x; // expected-warning {{equality comparison as an unused top-level statement}} \
// expected-note {{cast this comparison to void to silence this warning}}
p == p; // expected-warning {{equality comparison as an unused top-level statement}} \
// expected-note {{cast this comparison to void to silence this warning}} \
// expected-note {{use '=' to turn this equality comparison into an assignment}} \
@ -30,6 +32,8 @@ void test() {
a != b; // expected-warning {{inequality comparison as an unused top-level statement}} \
// expected-note {{cast this comparison to void to silence this warning}} \
// expected-note {{use '|=' to turn this inequality comparison into an or-assignment}}
A() == b; // expected-warning {{equality comparison as an unused top-level statement}} \
// expected-note {{cast this comparison to void to silence this warning}}
if (42) x == 7; // expected-warning {{equality comparison as an unused top-level statement}} \
// expected-note {{cast this comparison to void to silence this warning}} \
// expected-note {{use '=' to turn this equality comparison into an assignment}}