Author: faisalv
Date: Sun Nov 13 00:09:16 2016
New Revision: 286748
URL: http://llvm.org/viewvc/llvm-project?rev=286748&view=rev
Log:
Fix PR28366: Handle variables from enclosing local scopes more gracefully
during constant expression evaluation.
Only look for a variable's value in the constant expression evaluation
activation frame, if the variable was indeed declared in that frame, otherwise
it might be a constant expression and be usable within a nested local scope or
emit an error.
void f(char c) {
struct X {
static constexpr char f() {
return c; // error gracefully here as opposed to crashing.
}
};
int I = X::f();
}
Modified:
cfe/trunk/lib/AST/ExprConstant.cpp
cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp
cfe/trunk/test/SemaCXX/constant-expression-cxx11.cpp
cfe/trunk/test/SemaCXX/cxx1z-constexpr-lambdas.cpp
Modified: cfe/trunk/lib/AST/ExprConstant.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprConstant.cpp?rev=286748&r1=286747&r2=286748&view=diff
==============================================================================
--- cfe/trunk/lib/AST/ExprConstant.cpp (original)
+++ cfe/trunk/lib/AST/ExprConstant.cpp Sun Nov 13 00:09:16 2016
@@ -4803,10 +4803,21 @@ bool LValueExprEvaluator::VisitDeclRefEx
return Error(E);
}
+
bool LValueExprEvaluator::VisitVarDecl(const Expr *E, const VarDecl *VD) {
CallStackFrame *Frame = nullptr;
- if (VD->hasLocalStorage() && Info.CurrentCall->Index > 1)
- Frame = Info.CurrentCall;
+ if (VD->hasLocalStorage() && Info.CurrentCall->Index > 1) {
+ // Only if a local variable was declared in the function currently being
+ // evaluated, do we expect to be able to find its value in the current
+ // frame. (Otherwise it was likely declared in an enclosing context and
+ // could either have a valid evaluatable value (for e.g. a constexpr
+ // variable) or be ill-formed (and trigger an appropriate evaluation
+ // diagnostic)).
+ if (Info.CurrentCall->Callee &&
+ Info.CurrentCall->Callee->Equals(VD->getDeclContext())) {
+ Frame = Info.CurrentCall;
+ }
+ }
if (!VD->getType()->isReferenceType()) {
if (Frame) {
Modified: cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp?rev=286748&r1=286747&r2=286748&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp (original)
+++ cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp Sun Nov 13 00:09:16 2016
@@ -188,7 +188,7 @@ static void instantiateDependentEnableIf
SmallVector<PartialDiagnosticAt, 8> Diags;
if (A->getCond()->isValueDependent() && !Cond->isValueDependent() &&
- !Expr::isPotentialConstantExprUnevaluated(Cond, cast<FunctionDecl>(Tmpl),
+ !Expr::isPotentialConstantExprUnevaluated(Cond, cast<FunctionDecl>(New),
Diags)) {
S.Diag(A->getLocation(), diag::err_enable_if_never_constant_expr);
for (int I = 0, N = Diags.size(); I != N; ++I)
Modified: cfe/trunk/test/SemaCXX/constant-expression-cxx11.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/constant-expression-cxx11.cpp?rev=286748&r1=286747&r2=286748&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/constant-expression-cxx11.cpp (original)
+++ cfe/trunk/test/SemaCXX/constant-expression-cxx11.cpp Sun Nov 13 00:09:16
2016
@@ -2066,3 +2066,33 @@ namespace InheritedCtor {
constexpr Z z(1);
static_assert(z.w == 1 && z.x == 2 && z.y == 3 && z.z == 4, "");
}
+
+
+namespace PR28366 {
+namespace ns1 {
+
+void f(char c) { //expected-note2{{declared here}}
+ struct X {
+ static constexpr char f() { //expected-error{{never produces a constant
expression}}
+ return c; //expected-error{{reference to local}}
expected-note{{non-const variable}}
+ }
+ };
+ int I = X::f();
+}
+
+void g() {
+ const int c = 'c';
+ static const int d = 'd';
+ struct X {
+ static constexpr int f() {
+ return c + d;
+ }
+ };
+ static_assert(X::f() == 'c' + 'd',"");
+}
+
+
+} // end ns1
+
+} //end ns PR28366
+
Modified: cfe/trunk/test/SemaCXX/cxx1z-constexpr-lambdas.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/cxx1z-constexpr-lambdas.cpp?rev=286748&r1=286747&r2=286748&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/cxx1z-constexpr-lambdas.cpp (original)
+++ cfe/trunk/test/SemaCXX/cxx1z-constexpr-lambdas.cpp Sun Nov 13 00:09:16 2016
@@ -46,5 +46,17 @@ namespace ns3 {
} // end ns test_constexpr_call
-#endif // ndef CPP14_AND_EARLIER
+namespace test_captureless_lambda {
+void f() {
+ const char c = 'c';
+ auto L = [] { return c; };
+ constexpr char C = L();
+}
+
+void f(char c) { //expected-note{{declared here}}
+ auto L = [] { return c; }; //expected-error{{cannot be implicitly captured}}
expected-note{{lambda expression begins here}}
+ int I = L();
+}
+}
+#endif // ndef CPP14_AND_EARLIER
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