r363972 - Fix crash and rejects-valid when a later template parameter or default
Richard Smith via cfe-commits
cfe-commits at lists.llvm.org
Thu Jun 20 12:49:13 PDT 2019
Author: rsmith
Date: Thu Jun 20 12:49:13 2019
New Revision: 363972
URL: http://llvm.org/viewvc/llvm-project?rev=363972&view=rev
Log:
Fix crash and rejects-valid when a later template parameter or default
template argument contains a backreference to a dependently-typed
earlier parameter.
In a case like:
template<typename T, T A, decltype(A) = A> struct X {};
template<typename U> auto Y = X<U, 0>();
we previously treated both references to `A` in the third parameter as
being of type `int` when checking the template-id in `Y`. That`s wrong;
the type of `A` in these contexts is the dependent type `U`.
When we encounter a non-type template argument that we can't convert to
the parameter type because of type-dependence, we now insert a dependent
conversion node so that the SubstNonTypeTemplateParmExpr for the
template argument will have the parameter's type rather than whatever
type the argument had.
Modified:
cfe/trunk/lib/AST/ItaniumMangle.cpp
cfe/trunk/lib/Sema/Sema.cpp
cfe/trunk/lib/Sema/SemaTemplate.cpp
cfe/trunk/test/SemaTemplate/resolve-single-template-id.cpp
cfe/trunk/test/SemaTemplate/temp_arg_nontype.cpp
Modified: cfe/trunk/lib/AST/ItaniumMangle.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ItaniumMangle.cpp?rev=363972&r1=363971&r2=363972&view=diff
==============================================================================
--- cfe/trunk/lib/AST/ItaniumMangle.cpp (original)
+++ cfe/trunk/lib/AST/ItaniumMangle.cpp Thu Jun 20 12:49:13 2019
@@ -4499,7 +4499,7 @@ void CXXNameMangler::mangleTemplateArg(T
// It's possible to end up with a DeclRefExpr here in certain
// dependent cases, in which case we should mangle as a
// declaration.
- const Expr *E = A.getAsExpr()->IgnoreParens();
+ const Expr *E = A.getAsExpr()->IgnoreParenImpCasts();
if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
const ValueDecl *D = DRE->getDecl();
if (isa<VarDecl>(D) || isa<FunctionDecl>(D)) {
Modified: cfe/trunk/lib/Sema/Sema.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/Sema.cpp?rev=363972&r1=363971&r2=363972&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/Sema.cpp (original)
+++ cfe/trunk/lib/Sema/Sema.cpp Thu Jun 20 12:49:13 2019
@@ -491,6 +491,7 @@ ExprResult Sema::ImpCastExprToType(Expr
default:
llvm_unreachable("can't implicitly cast lvalue to rvalue with this cast "
"kind");
+ case CK_Dependent:
case CK_LValueToRValue:
case CK_ArrayToPointerDecay:
case CK_FunctionToPointerDecay:
@@ -499,7 +500,8 @@ ExprResult Sema::ImpCastExprToType(Expr
break;
}
}
- assert((VK == VK_RValue || !E->isRValue()) && "can't cast rvalue to lvalue");
+ assert((VK == VK_RValue || Kind == CK_Dependent || !E->isRValue()) &&
+ "can't cast rvalue to lvalue");
#endif
diagnoseNullableToNonnullConversion(Ty, E->getType(), E->getBeginLoc());
Modified: cfe/trunk/lib/Sema/SemaTemplate.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaTemplate.cpp?rev=363972&r1=363971&r2=363972&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaTemplate.cpp (original)
+++ cfe/trunk/lib/Sema/SemaTemplate.cpp Thu Jun 20 12:49:13 2019
@@ -4888,10 +4888,22 @@ bool Sema::CheckTemplateArgument(NamedDe
TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack,
Converted);
- NTTPType = SubstType(NTTPType,
- MultiLevelTemplateArgumentList(TemplateArgs),
- NTTP->getLocation(),
- NTTP->getDeclName());
+
+ // If the parameter is a pack expansion, expand this slice of the pack.
+ if (auto *PET = NTTPType->getAs<PackExpansionType>()) {
+ Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(*this,
+ ArgumentPackIndex);
+ NTTPType = SubstType(PET->getPattern(),
+ MultiLevelTemplateArgumentList(TemplateArgs),
+ NTTP->getLocation(),
+ NTTP->getDeclName());
+ } else {
+ NTTPType = SubstType(NTTPType,
+ MultiLevelTemplateArgumentList(TemplateArgs),
+ NTTP->getLocation(),
+ NTTP->getDeclName());
+ }
+
// If that worked, check the non-type template parameter type
// for validity.
if (!NTTPType.isNull())
@@ -6310,9 +6322,7 @@ ExprResult Sema::CheckTemplateArgument(N
// When checking a deduced template argument, deduce from its type even if
// the type is dependent, in order to check the types of non-type template
// arguments line up properly in partial ordering.
- Optional<unsigned> Depth;
- if (CTAK != CTAK_Specified)
- Depth = Param->getDepth() + 1;
+ Optional<unsigned> Depth = Param->getDepth() + 1;
if (DeduceAutoType(
Context.getTrivialTypeSourceInfo(ParamType, Param->getLocation()),
Arg, ParamType, Depth) == DAR_Failed) {
@@ -6367,9 +6377,24 @@ ExprResult Sema::CheckTemplateArgument(N
// If either the parameter has a dependent type or the argument is
// type-dependent, there's nothing we can check now.
if (ParamType->isDependentType() || Arg->isTypeDependent()) {
- // FIXME: Produce a cloned, canonical expression?
- Converted = TemplateArgument(Arg);
- return Arg;
+ // Force the argument to the type of the parameter to maintain invariants.
+ auto *PE = dyn_cast<PackExpansionExpr>(Arg);
+ if (PE)
+ Arg = PE->getPattern();
+ ExprResult E = ImpCastExprToType(
+ Arg, ParamType.getNonLValueExprType(Context), CK_Dependent,
+ ParamType->isLValueReferenceType() ? VK_LValue :
+ ParamType->isRValueReferenceType() ? VK_XValue : VK_RValue);
+ if (E.isInvalid())
+ return ExprError();
+ if (PE) {
+ // Recreate a pack expansion if we unwrapped one.
+ E = new (Context)
+ PackExpansionExpr(E.get()->getType(), E.get(), PE->getEllipsisLoc(),
+ PE->getNumExpansions());
+ }
+ Converted = TemplateArgument(E.get());
+ return E;
}
// The initialization of the parameter from the argument is
Modified: cfe/trunk/test/SemaTemplate/resolve-single-template-id.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaTemplate/resolve-single-template-id.cpp?rev=363972&r1=363971&r2=363972&view=diff
==============================================================================
--- cfe/trunk/test/SemaTemplate/resolve-single-template-id.cpp (original)
+++ cfe/trunk/test/SemaTemplate/resolve-single-template-id.cpp Thu Jun 20 12:49:13 2019
@@ -88,3 +88,15 @@ struct rdar9108698 {
void test_rdar9108698(rdar9108698 x) {
x.f<int>; // expected-error{{reference to non-static member function must be called}}
}
+
+namespace GCC_PR67898 {
+ void f(int);
+ void f(float);
+ template<typename T, T F, T G, bool b = F == G> struct X {
+ static_assert(b, "");
+ };
+ template<typename T> void test1() { X<void(T), f, f>(); }
+ template<typename T> void test2() { X<void(*)(T), f, f>(); }
+ template void test1<int>();
+ template void test2<int>();
+}
Modified: cfe/trunk/test/SemaTemplate/temp_arg_nontype.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaTemplate/temp_arg_nontype.cpp?rev=363972&r1=363971&r2=363972&view=diff
==============================================================================
--- cfe/trunk/test/SemaTemplate/temp_arg_nontype.cpp (original)
+++ cfe/trunk/test/SemaTemplate/temp_arg_nontype.cpp Thu Jun 20 12:49:13 2019
@@ -463,3 +463,22 @@ namespace pointer_to_char_array {
T foo = "foo";
void g() { A<&foo>().f(); }
}
+
+namespace dependent_backreference {
+ struct Incomplete; // expected-note 2{{forward declaration}}
+ Incomplete f(int); // expected-note 2{{here}}
+ int f(short);
+
+ template<typename T, T Value, int(*)[sizeof(f(Value))]> struct X {}; // expected-error 2{{incomplete}}
+ int arr[sizeof(int)];
+ // When checking this template-id, we must not treat 'Value' as having type
+ // 'int'; its type is the dependent type 'T'.
+ template<typename T> void f() { X<T, 0, &arr> x; } // expected-note {{substituting}}
+ void g() { f<short>(); }
+ void h() { f<int>(); } // expected-note {{instantiation}}
+
+ // The second of these is OK to diagnose eagerly because 'Value' has the
+ // non-dependent type 'int'.
+ template<short S> void a() { X<short, S, &arr> x; }
+ template<short S> void b() { X<int, S, &arr> x; } // expected-note {{substituting}}
+}
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