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[clang] P2266: apply move elision rules on throw expr nested in function prototypes 

Our rules to determine if the throw expression are within the variable
scope were giving a false negative result in case the throw expression
would appear within a decltype in a nested function declaration.

Per P2266R3, the relevant rule is: [expr.prim.id.unqual]/2
```
    if the id-expression (possibly parenthesized) is the operand of a throw-expression, and names an implicitly movable entity that belongs to a scope that does not contain the compound-statement of the innermost lambda-expression, try-block , or function-try-block (if any) whose compound-statement or ctor-initializer encloses the throw-expression.
```

This fixes PR54341.

Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>

Reviewed By: rsmith

Differential Revision: https://reviews.llvm.org/D127075
This commit is contained in:
Matheus Izvekov 2022-06-05 21:50:00 +02:00
parent 5cac7cda95
commit 43ef17cac1
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2 changed files with 5 additions and 5 deletions
clang
lib/Sema
SemaExprCXX.cpp
test/CXX/class/class.init/class.copy.elision
p3.cpp

4
clang/lib/Sema/SemaExprCXX.cpp
View File

@ -843,10 +843,10 @@ Sema::ActOnCXXThrow(Scope *S, SourceLocation OpLoc, Expr *Ex) {
break;
}
// FIXME: Many of the scope checks here seem incorrect.
if (S->getFlags() &
(Scope::FnScope | Scope::ClassScope | Scope::BlockScope |
Scope::FunctionPrototypeScope | Scope::ObjCMethodScope |
Scope::TryScope))
Scope::ObjCMethodScope | Scope::TryScope))
break;
}
}

6
clang/test/CXX/class/class.init/class.copy.elision/p3.cpp
View File

@ -98,7 +98,7 @@ struct A1 {
A1(const A1 &);
A1(A1 &&) = delete;
// expected-note@-1 2{{'A1' has been explicitly marked deleted here}}
// cxx11_2b-note@-2 {{'A1' has been explicitly marked deleted here}}
// cxx11_2b-note@-2 3{{'A1' has been explicitly marked deleted here}}
};
void test1() {
try {
@ -132,10 +132,10 @@ void test3(A1 a) try {
namespace PR54341 {
void test4(A1 a) {
void f(decltype((throw a, 0)));
// expected-warning@-1 {{has no effect}}
// expected-error@-1 {{call to deleted constructor of 'test_throw_parameter::A1'}}
void g(int = decltype(throw a, 0){});
// expected-warning@-1 {{has no effect}}
// expected-error@-1 {{call to deleted constructor of 'test_throw_parameter::A1'}}
}
void test5(A1 a, int = decltype(throw a, 0){}) {}