erichkeane created this revision.
As the bug report says,
struct A
{
template<typename T> operator T();
};
void foo()
{
A().operator auto();
}
causes: "undeduced type in IR-generation
UNREACHABLE executed at llvm/tools/clang/lib/CodeGen/CodeGenFunction.cpp:208!"
The problem is that in this case, "T" is being deduced as "auto", which I
believe is incorrect.
The 'operator auto' implementation in Clang is standards compliant, however
there is a defect report against core (1670).
https://reviews.llvm.org/D34370
Files:
lib/Sema/SemaLookup.cpp
test/SemaCXX/cxx1y-deduced-return-type.cpp
Index: test/SemaCXX/cxx1y-deduced-return-type.cpp
===================================================================
--- test/SemaCXX/cxx1y-deduced-return-type.cpp
+++ test/SemaCXX/cxx1y-deduced-return-type.cpp
@@ -55,6 +55,20 @@
return "goodbye";
}
+// Allow 'operator auto' to call only the explicit operator auto.
+struct BothOps{
+ template<typename T> operator T();
+ operator auto() { return 0; }
+};
+struct JustTemplateOp {
+ template<typename T> operator T();
+};
+
+auto c() {
+ BothOps().operator auto(); // ok
+ JustTemplateOp().operator auto(); // expected-error {{no member named
'operator auto' in 'JustTemplateOp'}}
+}
+
auto *ptr_1() {
return 100; // expected-error {{cannot deduce return type 'auto *' from
returned value of type 'int'}}
}
Index: lib/Sema/SemaLookup.cpp
===================================================================
--- lib/Sema/SemaLookup.cpp
+++ lib/Sema/SemaLookup.cpp
@@ -862,6 +862,17 @@
if (!Record->isCompleteDefinition())
return Found;
+ // For conversion operators, 'operator auto' should only match
+ // 'operator auto'. Since 'auto' is not a type, it shouldn't be considered
+ // as a candidate for template substitution.
+ if (R.getLookupName().getNameKind() ==
+ DeclarationName::CXXConversionFunctionName) {
+ auto *Ty =
+ dyn_cast<AutoType>(R.getLookupName().getCXXNameType());
+ if (Ty && Ty->isUndeducedType())
+ return Found;
+ }
+
for (CXXRecordDecl::conversion_iterator U = Record->conversion_begin(),
UEnd = Record->conversion_end(); U != UEnd; ++U) {
FunctionTemplateDecl *ConvTemplate = dyn_cast<FunctionTemplateDecl>(*U);
Index: test/SemaCXX/cxx1y-deduced-return-type.cpp
===================================================================
--- test/SemaCXX/cxx1y-deduced-return-type.cpp
+++ test/SemaCXX/cxx1y-deduced-return-type.cpp
@@ -55,6 +55,20 @@
return "goodbye";
}
+// Allow 'operator auto' to call only the explicit operator auto.
+struct BothOps{
+ template<typename T> operator T();
+ operator auto() { return 0; }
+};
+struct JustTemplateOp {
+ template<typename T> operator T();
+};
+
+auto c() {
+ BothOps().operator auto(); // ok
+ JustTemplateOp().operator auto(); // expected-error {{no member named 'operator auto' in 'JustTemplateOp'}}
+}
+
auto *ptr_1() {
return 100; // expected-error {{cannot deduce return type 'auto *' from returned value of type 'int'}}
}
Index: lib/Sema/SemaLookup.cpp
===================================================================
--- lib/Sema/SemaLookup.cpp
+++ lib/Sema/SemaLookup.cpp
@@ -862,6 +862,17 @@
if (!Record->isCompleteDefinition())
return Found;
+ // For conversion operators, 'operator auto' should only match
+ // 'operator auto'. Since 'auto' is not a type, it shouldn't be considered
+ // as a candidate for template substitution.
+ if (R.getLookupName().getNameKind() ==
+ DeclarationName::CXXConversionFunctionName) {
+ auto *Ty =
+ dyn_cast<AutoType>(R.getLookupName().getCXXNameType());
+ if (Ty && Ty->isUndeducedType())
+ return Found;
+ }
+
for (CXXRecordDecl::conversion_iterator U = Record->conversion_begin(),
UEnd = Record->conversion_end(); U != UEnd; ++U) {
FunctionTemplateDecl *ConvTemplate = dyn_cast<FunctionTemplateDecl>(*U);
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