m4tx created this revision.
m4tx added reviewers: lebedev.ri, rsmith, klimek.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
int x;
return x = 5;
For a code like above, GCC produces a warning suggesting using parentheses
about the assignment. This change makes clang produce similar warning to,
suggesting either changing the operator to `==`, or wrap the expression inside
parentheses.
This is based off D45401 <https://reviews.llvm.org/D45401>.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D63089
Files:
clang/lib/Sema/SemaChecking.cpp
clang/lib/Sema/SemaExpr.cpp
clang/lib/Sema/SemaExprCXX.cpp
clang/test/Sema/parentheses.c
clang/test/Sema/parentheses.cpp
Index: clang/test/Sema/parentheses.cpp
===================================================================
--- clang/test/Sema/parentheses.cpp
+++ clang/test/Sema/parentheses.cpp
@@ -215,3 +215,15 @@
// fix-it:"{{.*}}":{[[@LINE-9]]:20-[[@LINE-9]]:20}:")"
}
}
+
+bool return_assign() {
+ int i;
+ return i = 4; // expected-warning {{assignment as a condition}} \
+ // expected-note{{place parentheses around the assignment to
silence this warning}} \
+ // expected-note{{use '==' to turn this assignment into an
equality comparison}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:10-[[@LINE-3]]:10}:"("
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:15-[[@LINE-4]]:15}:")"
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-5]]:12-[[@LINE-5]]:13}:"=="
+
+ return (i = 4);
+}
Index: clang/test/Sema/parentheses.c
===================================================================
--- clang/test/Sema/parentheses.c
+++ clang/test/Sema/parentheses.c
@@ -14,6 +14,18 @@
if ((i = 4)) {}
}
+_Bool return_assign(void) {
+ int i;
+ return i = 4; // expected-warning {{assignment as a condition}} \
+ // expected-note{{place parentheses around the assignment to
silence this warning}} \
+ // expected-note{{use '==' to turn this assignment into an
equality comparison}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:10-[[@LINE-3]]:10}:"("
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:15-[[@LINE-4]]:15}:")"
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-5]]:12-[[@LINE-5]]:13}:"=="
+
+ return (i = 4);
+}
+
void bitwise_rel(unsigned i) {
(void)(i & 0x2 == 0); // expected-warning {{& has lower precedence than ==}}
\
// expected-note{{place parentheses around the '=='
expression to silence this warning}} \
Index: clang/lib/Sema/SemaExprCXX.cpp
===================================================================
--- clang/lib/Sema/SemaExprCXX.cpp
+++ clang/lib/Sema/SemaExprCXX.cpp
@@ -3926,6 +3926,11 @@
FromType = From->getType();
}
+ // Warn on assignments inside implicit casts (= instead of ==)
+ if (SCS.Second == ICK_Boolean_Conversion || FromType == Context.BoolTy) {
+ DiagnoseAssignmentAsCondition(From->IgnoreImpCasts());
+ }
+
// If we're converting to an atomic type, first convert to the corresponding
// non-atomic type.
QualType ToAtomicType;
Index: clang/lib/Sema/SemaExpr.cpp
===================================================================
--- clang/lib/Sema/SemaExpr.cpp
+++ clang/lib/Sema/SemaExpr.cpp
@@ -16375,7 +16375,10 @@
ExprResult Sema::CheckBooleanCondition(SourceLocation Loc, Expr *E,
bool IsConstexpr) {
- DiagnoseAssignmentAsCondition(E);
+ // C++ implicit casts are checked inside PerformImplicitConversion
+ if (!getLangOpts().CPlusPlus) {
+ DiagnoseAssignmentAsCondition(E);
+ }
if (ParenExpr *parenE = dyn_cast<ParenExpr>(E))
DiagnoseEqualityWithExtraParens(parenE);
Index: clang/lib/Sema/SemaChecking.cpp
===================================================================
--- clang/lib/Sema/SemaChecking.cpp
+++ clang/lib/Sema/SemaChecking.cpp
@@ -9700,6 +9700,13 @@
<< FD << getLangOpts().CPlusPlus11;
}
}
+
+ // C++ implicit casts are checked inside PerformImplicitConversion
+ if (!getLangOpts().CPlusPlus) {
+ if (ImplicitCastExpr *CastExpr = dyn_cast<ImplicitCastExpr>(RetValExp)) {
+ DiagnoseAssignmentAsCondition(CastExpr->IgnoreImpCasts());
+ }
+ }
}
//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===//
Index: clang/test/Sema/parentheses.cpp
===================================================================
--- clang/test/Sema/parentheses.cpp
+++ clang/test/Sema/parentheses.cpp
@@ -215,3 +215,15 @@
// fix-it:"{{.*}}":{[[@LINE-9]]:20-[[@LINE-9]]:20}:")"
}
}
+
+bool return_assign() {
+ int i;
+ return i = 4; // expected-warning {{assignment as a condition}} \
+ // expected-note{{place parentheses around the assignment to silence this warning}} \
+ // expected-note{{use '==' to turn this assignment into an equality comparison}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:10-[[@LINE-3]]:10}:"("
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:15-[[@LINE-4]]:15}:")"
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-5]]:12-[[@LINE-5]]:13}:"=="
+
+ return (i = 4);
+}
Index: clang/test/Sema/parentheses.c
===================================================================
--- clang/test/Sema/parentheses.c
+++ clang/test/Sema/parentheses.c
@@ -14,6 +14,18 @@
if ((i = 4)) {}
}
+_Bool return_assign(void) {
+ int i;
+ return i = 4; // expected-warning {{assignment as a condition}} \
+ // expected-note{{place parentheses around the assignment to silence this warning}} \
+ // expected-note{{use '==' to turn this assignment into an equality comparison}}
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:10-[[@LINE-3]]:10}:"("
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-4]]:15-[[@LINE-4]]:15}:")"
+ // CHECK: fix-it:"{{.*}}":{[[@LINE-5]]:12-[[@LINE-5]]:13}:"=="
+
+ return (i = 4);
+}
+
void bitwise_rel(unsigned i) {
(void)(i & 0x2 == 0); // expected-warning {{& has lower precedence than ==}} \
// expected-note{{place parentheses around the '==' expression to silence this warning}} \
Index: clang/lib/Sema/SemaExprCXX.cpp
===================================================================
--- clang/lib/Sema/SemaExprCXX.cpp
+++ clang/lib/Sema/SemaExprCXX.cpp
@@ -3926,6 +3926,11 @@
FromType = From->getType();
}
+ // Warn on assignments inside implicit casts (= instead of ==)
+ if (SCS.Second == ICK_Boolean_Conversion || FromType == Context.BoolTy) {
+ DiagnoseAssignmentAsCondition(From->IgnoreImpCasts());
+ }
+
// If we're converting to an atomic type, first convert to the corresponding
// non-atomic type.
QualType ToAtomicType;
Index: clang/lib/Sema/SemaExpr.cpp
===================================================================
--- clang/lib/Sema/SemaExpr.cpp
+++ clang/lib/Sema/SemaExpr.cpp
@@ -16375,7 +16375,10 @@
ExprResult Sema::CheckBooleanCondition(SourceLocation Loc, Expr *E,
bool IsConstexpr) {
- DiagnoseAssignmentAsCondition(E);
+ // C++ implicit casts are checked inside PerformImplicitConversion
+ if (!getLangOpts().CPlusPlus) {
+ DiagnoseAssignmentAsCondition(E);
+ }
if (ParenExpr *parenE = dyn_cast<ParenExpr>(E))
DiagnoseEqualityWithExtraParens(parenE);
Index: clang/lib/Sema/SemaChecking.cpp
===================================================================
--- clang/lib/Sema/SemaChecking.cpp
+++ clang/lib/Sema/SemaChecking.cpp
@@ -9700,6 +9700,13 @@
<< FD << getLangOpts().CPlusPlus11;
}
}
+
+ // C++ implicit casts are checked inside PerformImplicitConversion
+ if (!getLangOpts().CPlusPlus) {
+ if (ImplicitCastExpr *CastExpr = dyn_cast<ImplicitCastExpr>(RetValExp)) {
+ DiagnoseAssignmentAsCondition(CastExpr->IgnoreImpCasts());
+ }
+ }
}
//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===//
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