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[Diagnostics] Do not diagnose unsigned shifts in boolean context (-Wint-in-bool-context) 

I was looking at old GCC's patch. Current "trunk" version avoids warning for unsigned case, GCC warns only for signed shifts.

llvm-svn: 372708
This commit is contained in:
David Bolvansky 2019-09-24 09:14:33 +00:00
parent 52c55d7fb5
commit 849fd28cf0
3 changed files with 39 additions and 32 deletions
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4
clang/include/clang/Basic/DiagnosticSemaKinds.td
View File

@ -5722,10 +5722,10 @@ def note_precedence_conditional_first : Note<
def warn_enum_constant_in_bool_context : Warning<
"converting the enum constant to a boolean">,
InGroup<IntInBoolContext>;
InGroup<IntInBoolContext>, DefaultIgnore;
def warn_left_shift_in_bool_context : Warning<
"converting the result of '<<' to a boolean; did you mean '(%0) != 0'?">,
InGroup<IntInBoolContext>;
InGroup<IntInBoolContext>, DefaultIgnore;
def warn_logical_instead_of_bitwise : Warning<
"use of logical '%0' with constant operand">,
InGroup<DiagGroup<"constant-logical-operand">>;

47
clang/lib/Sema/SemaChecking.cpp
View File

@ -11296,44 +11296,39 @@ static bool isSameWidthConstantConversion(Sema &S, Expr *E, QualType T,
return true;
}
static const IntegerLiteral *getIntegerLiteral(Expr *E) {
const auto *IL = dyn_cast<IntegerLiteral>(E);
if (!IL) {
if (auto *UO = dyn_cast<UnaryOperator>(E)) {
if (UO->getOpcode() == UO_Minus)
return dyn_cast<IntegerLiteral>(UO->getSubExpr());
}
}
return IL;
}
static void DiagnoseIntInBoolContext(Sema &S, Expr *E) {
E = E->IgnoreParenImpCasts();
SourceLocation ExprLoc = E->getExprLoc();
if (const auto *BO = dyn_cast<BinaryOperator>(E)) {
BinaryOperator::Opcode Opc = BO->getOpcode();
if (Opc == BO_Shl)
// Do not diagnose unsigned shifts.
if (Opc == BO_Shl && E->getType()->isSignedIntegerType())
S.Diag(ExprLoc, diag::warn_left_shift_in_bool_context) << E;
}
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;
}
}
const auto *LHS = getIntegerLiteral(CO->getTrueExpr());
if (!LHS)
return;
const auto *RHS = getIntegerLiteral(CO->getFalseExpr());
if (!RHS)
return;
if ((LHS->getValue() == 0 || LHS->getValue() == 1) &&
(RHS->getValue() == 0 || RHS->getValue() == 1))
// Do not diagnose common idioms
// Do not diagnose common idioms.
return;
if (LHS->getValue() != 0 && LHS->getValue() != 0)
S.Diag(ExprLoc, diag::warn_integer_constants_in_conditional_always_true);

20
clang/test/Sema/warn-int-in-bool-context.c
View File

@ -7,6 +7,8 @@
#define TWO 2
#define SHIFT(l, r) l << r
#define MM a << a
#define AF 1 << 7
#ifdef __cplusplus
typedef bool boolean;
@ -20,15 +22,25 @@ enum num {
two,
};
int test(int a, enum num n) {
int test(int a, unsigned b, enum num n) {
boolean r;
r = (1 << 3); // expected-warning {{converting the result of '<<' to a boolean; did you mean '(1 << 3) != 0'?}}
r = TWO << 7; // expected-warning {{converting the result of '<<' to a boolean; did you mean '(2 << 7) != 0'?}}
r = a << a; // expected-warning {{converting the result of '<<' to a boolean; did you mean '(a << a) != 0'?}}
r = MM; // expected-warning {{converting the result of '<<' to a boolean; did you mean '(a << a) != 0'?}}
r = (1 << 7); // expected-warning {{converting the result of '<<' to a boolean; did you mean '(1 << 7) != 0'?}}
r = 2UL << 2;
r = 2 << b; // expected-warning {{converting the result of '<<' to a boolean; did you mean '(2 << b) != 0'?}}
r = (unsigned)(2 << b);
r = b << 7;
r = (1 << a); // expected-warning {{converting the result of '<<' to a boolean; did you mean '(1 << a) != 0'?}}
r = TWO << a; // expected-warning {{converting the result of '<<' to a boolean; did you mean '(2 << a) != 0'?}}
r = a << 7; // expected-warning {{converting the result of '<<' to a boolean; did you mean '(a << 7) != 0'?}}
r = ONE << a; // expected-warning {{converting the result of '<<' to a boolean; did you mean '(1 << a) != 0'?}}
if (TWO << 4) // expected-warning {{converting the result of '<<' to a boolean; did you mean '(2 << 4) != 0'?}}
if (TWO << a) // expected-warning {{converting the result of '<<' to a boolean; did you mean '(2 << a) != 0'?}}
return a;
for (a = 0; 1 << a; a++) // expected-warning {{converting the result of '<<' to a boolean; did you mean '(1 << a) != 0'?}}
;
if (a << TWO) // expected-warning {{converting the result of '<<' to a boolean; did you mean '(a << 2) != 0'?}}
return a;