replica
/
hanchenye-llvm-project
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Don't produce a 'returning reference to local' warning if a lambda returns a 

reference (or pointer) to a variable from the closure object or from the
surrounding function scope.

llvm-svn: 200494
This commit is contained in:
Richard Smith 2014-01-30 22:05:38 +00:00
parent 0115b0879c
commit 40f08ebece
2 changed files with 28 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
clang/lib/Sema/SemaChecking.cpp
View File

@ -4136,6 +4136,10 @@ static Expr *EvalAddr(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars,
case Stmt::DeclRefExprClass: {
DeclRefExpr *DR = cast<DeclRefExpr>(E);
// If we leave the immediate function, the lifetime isn't about to end.
if (DR->refersToEnclosingLocal())
return 0;
if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl()))
// If this is a reference variable, follow through to the expression that
// it points to.
@ -4292,6 +4296,10 @@ do {
// local storage within the function, and if so, return the expression.
DeclRefExpr *DR = cast<DeclRefExpr>(E);
// If we leave the immediate function, the lifetime isn't about to end.
if (DR->refersToEnclosingLocal())
return 0;
if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) {
// Check if it refers to itself, e.g. "int& i = i;".
if (V == ParentDecl)

23
clang/test/SemaCXX/return-stack-addr.cpp
View File

@ -1,4 +1,4 @@
// RUN: %clang_cc1 -fsyntax-only -verify %s
// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s
int* ret_local() {
int x = 1;
@ -108,6 +108,11 @@ int* ret_cpp_const_cast(const int x) {
return const_cast<int*>(&x); // expected-warning {{address of stack memory}}
}
struct A { virtual ~A(); }; struct B : A {};
A* ret_cpp_dynamic_cast(B b) {
return dynamic_cast<A*>(&b); // expected-warning {{address of stack memory}}
}
// PR 7999 - handle the case where a field is itself a reference.
template <typename T> struct PR7999 {
PR7999(T& t) : value(t) {}
@ -137,5 +142,17 @@ namespace PR8774 {
}
}
// TODO: test case for dynamic_cast. clang does not yet have
// support for C++ classes to write such a test case.
// Don't warn about returning a local variable from a surrounding function if
// we're within a lambda-expression.
void ret_from_lambda() {
int a;
int &b = a;
(void) [&]() -> int& { return a; };
(void) [&]() -> int& { return b; };
(void) [=]() mutable -> int& { return a; };
(void) [=]() mutable -> int& { return b; };
(void) [&]() -> int& { int a; return a; }; // expected-warning {{reference to stack}}
(void) [=]() -> int& { int a; return a; }; // expected-warning {{reference to stack}}
(void) [&]() -> int& { int &a = b; return a; };
(void) [=]() mutable -> int& { int &a = b; return a; };
}