Index: clang/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -2473,6 +2473,8 @@
def warn_cxx11_compat_deduced_return_type : Warning<
"return type deduction is incompatible with C++ standards before C++14">,
InGroup<CXXPre14Compat>, DefaultIgnore;
+def note_deducing_return_type_for : Note<
+ "deducing return type for %0">;
// C++11 override control
def override_keyword_only_allowed_on_virtual_member_functions : Error<
Index: clang/include/clang/Sema/Sema.h
===================================================================
--- clang/include/clang/Sema/Sema.h
+++ clang/include/clang/Sema/Sema.h
@@ -8856,7 +8856,10 @@
/// Memoization means we are _not_ instantiating a template because
/// it is already instantiated (but we entered a context where we
/// would have had to if it was not already instantiated).
- Memoization
+ Memoization,
+
+ /// We are deducing a function return type from its return statement.
+ ReturnTypeDeduction,
} Kind;
/// Was the enclosing context a non-instantiation SFINAE context?
Index: clang/lib/Frontend/FrontendActions.cpp
===================================================================
--- clang/lib/Frontend/FrontendActions.cpp
+++ clang/lib/Frontend/FrontendActions.cpp
@@ -465,6 +465,8 @@
return "InitializingStructuredBinding";
case CodeSynthesisContext::MarkingClassDllexported:
return "MarkingClassDllexported";
+ case CodeSynthesisContext::ReturnTypeDeduction:
+ return "ReturnTypeDeduction";
}
return "";
}
Index: clang/lib/Sema/SemaStmt.cpp
===================================================================
--- clang/lib/Sema/SemaStmt.cpp
+++ clang/lib/Sema/SemaStmt.cpp
@@ -3757,6 +3757,24 @@
.getReturnLoc();
}
+namespace {
+struct DeducingReturnType {
+ Sema &S;
+ explicit DeducingReturnType(Sema& S, TypeLoc OrigResultType, FunctionDecl *FD)
+ : S(S) {
+ Sema::CodeSynthesisContext Ctx;
+ Ctx.Kind = Sema::CodeSynthesisContext::ReturnTypeDeduction;
+ Ctx.PointOfInstantiation = OrigResultType.getBeginLoc();
+ Ctx.Entity = FD;
+ Ctx.InstantiationRange = OrigResultType.getSourceRange();
+ S.pushCodeSynthesisContext(Ctx);
+ }
+ ~DeducingReturnType() {
+ S.popCodeSynthesisContext();
+ }
+};
+} // namespace
+
/// Deduce the return type for a function from a returned expression, per
/// C++1y [dcl.spec.auto]p6.
bool Sema::DeduceFunctionTypeFromReturnExpr(FunctionDecl *FD,
@@ -3770,6 +3788,7 @@
return false;
TypeLoc OrigResultType = getReturnTypeLoc(FD);
+ DeducingReturnType DRT(*this, OrigResultType, FD);
QualType Deduced;
if (RetExpr && isa<InitListExpr>(RetExpr)) {
Index: clang/lib/Sema/SemaTemplateInstantiate.cpp
===================================================================
--- clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -213,6 +213,7 @@
case RewritingOperatorAsSpaceship:
case InitializingStructuredBinding:
case MarkingClassDllexported:
+ case ReturnTypeDeduction:
return false;
// This function should never be called when Kind's value is Memoization.
@@ -773,6 +774,17 @@
case CodeSynthesisContext::Memoization:
break;
+ case CodeSynthesisContext::ReturnTypeDeduction:
+ // PointOfInstantiation and InstantiationRange both point at the AutoType
+ // in the function declaration. If this is a lambda with an implied 'auto',
+ // there is no source location for that AutoType, so we shouldn't emit
+ // the note.
+ if (Active->PointOfInstantiation.isValid())
+ Diags.Report(Active->PointOfInstantiation,
+ diag::note_deducing_return_type_for)
+ << cast<FunctionDecl>(Active->Entity) << Active->InstantiationRange;
+ break;
+
case CodeSynthesisContext::ConstraintsCheck: {
unsigned DiagID = 0;
if (!Active->Entity) {
@@ -847,6 +859,7 @@
case CodeSynthesisContext::ParameterMappingSubstitution:
case CodeSynthesisContext::ConstraintNormalization:
case CodeSynthesisContext::NestedRequirementConstraintsCheck:
+ case CodeSynthesisContext::ReturnTypeDeduction:
// This is a template instantiation, so there is no SFINAE.
return None;
Index: clang/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p2-1z.cpp
===================================================================
--- clang/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p2-1z.cpp
+++ clang/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p2-1z.cpp
@@ -26,6 +26,7 @@
return 7.6;
else
return 5; // expected-error {{deduced as 'int' here but deduced as 'const char *' in earlier}}
+ // expected-note@-9 {{deducing return type for 'c'}}
}
template<int k> auto d() {
Index: clang/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p7-cxx14.cpp
===================================================================
--- clang/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p7-cxx14.cpp
+++ clang/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p7-cxx14.cpp
@@ -97,4 +97,6 @@
using Int = decltype(f5da(0));
auto init_list_1() { return { 1, 2, 3 }; } // expected-error {{cannot deduce return type from initializer list}}
+ // expected-note@-1 {{deducing return type for 'init_list_1'}}
decltype(auto) init_list_2() { return { 1, 2, 3 }; } // expected-error {{cannot deduce return type from initializer list}}
+ // expected-note@-1 {{deducing return type for 'init_list_2'}}
Index: clang/test/CXX/dcl/dcl.spec/dcl.type/dcl.spec.auto/p6.cpp
===================================================================
--- clang/test/CXX/dcl/dcl.spec/dcl.type/dcl.spec.auto/p6.cpp
+++ clang/test/CXX/dcl/dcl.spec/dcl.type/dcl.spec.auto/p6.cpp
@@ -20,6 +20,7 @@
}
Large auto test1() { // expected-error{{deduced type 'char' does not satisfy 'Large'}}
+ // expected-note@-1{{deducing return type for 'test1'}}
Large auto i = 'a';
// expected-error@-1{{deduced type 'char' does not satisfy 'Large'}}
Large auto j = 10;
@@ -36,6 +37,7 @@
::Large auto test2() { return 10; }
LargerThan<4> auto test3() { return 10; }
// expected-error@-1{{deduced type 'int' does not satisfy 'LargerThan<4>'}}
+// expected-note@-2{{deducing return type for 'test3'}}
::LargerThan<2> auto test4() { return 10; }
Large auto test5() -> void;
Index: clang/test/SemaCUDA/autoret-global.cu
===================================================================
--- clang/test/SemaCUDA/autoret-global.cu
+++ clang/test/SemaCUDA/autoret-global.cu
@@ -19,6 +19,7 @@
__global__ auto f2(int x) {
return x + 1;
// expected-error@-2 {{kernel function type 'auto (int)' must have void return type}}
+ // expected-note@-3 {{deducing return type for 'f2'}}
}
template <bool Cond, typename T = void> struct enable_if { typedef T type; };
Index: clang/test/SemaCXX/cxx2b-consteval-if.cpp
===================================================================
--- clang/test/SemaCXX/cxx2b-consteval-if.cpp
+++ clang/test/SemaCXX/cxx2b-consteval-if.cpp
@@ -4,11 +4,13 @@
constexpr auto f() {
if consteval { return 0; }
if !consteval { return 0.0; } // expected-error {{'auto' in return type deduced as 'double' here but deduced as 'int' in earlier return statement}}
+ // expected-note@-3 {{deducing return type for 'f'}}
}
constexpr auto g() {
if !consteval { return 0; }
if consteval { return 0.0; } // expected-error {{'auto' in return type deduced as 'double' here but deduced as 'int' in earlier return statement}}
+ // expected-note@-3 {{deducing return type for 'g'}}
}
constexpr auto h() {
@@ -24,6 +26,7 @@
return 2;
} else {
return 1.0; // expected-error {{'auto' in return type deduced as 'double' here but deduced as 'int' in earlier return statement}}
+ // expected-note@-8 {{deducing return type for 'i'}}
}
}
Index: clang/test/SemaCXX/deduced-return-type-cxx14.cpp
===================================================================
--- clang/test/SemaCXX/deduced-return-type-cxx14.cpp
+++ clang/test/SemaCXX/deduced-return-type-cxx14.cpp
@@ -82,6 +82,7 @@
auto *ptr_1() {
return 100; // expected-error {{cannot deduce return type 'auto *' from returned value of type 'int'}}
+ // expected-note@-2 {{deducing return type for 'ptr_1'}}
}
const auto &ref_1() {
@@ -90,6 +91,7 @@
auto init_list() {
return { 1, 2, 3 }; // expected-error {{cannot deduce return type from initializer list}}
+ // expected-note@-2 {{deducing return type for 'init_list'}}
}
auto fwd_decl(); // expected-note 2{{here}}
@@ -122,6 +124,7 @@
if (false)
return;
return 0; // expected-error {{'auto' in return type deduced as 'int' here but deduced as 'void' in earlier return statement}}
+ // expected-note@-6 {{deducing return type for 'void_ret_4'}}
}
namespace Templates {
Index: clang/test/SemaCXX/deduced-return-void.cpp
===================================================================
--- clang/test/SemaCXX/deduced-return-void.cpp
+++ clang/test/SemaCXX/deduced-return-void.cpp
@@ -16,10 +16,12 @@
auto f4() {
return i;
return; // expected-error {{'auto' in return type deduced as 'void' here but deduced as 'int' in earlier return statement}}
+ // expected-note@-3 {{deducing return type for 'f4'}}
}
auto f5() {
return i;
return void(); // expected-error {{'auto' in return type deduced as 'void' here but deduced as 'int' in earlier return statement}}
+ // expected-note@-3 {{deducing return type for 'f5'}}
}
auto l1 = []() { };
@@ -44,10 +46,12 @@
decltype(auto) f4() {
return i;
return; // expected-error {{'decltype(auto)' in return type deduced as 'void' here but deduced as 'int' in earlier return statement}}
+ // expected-note@-3 {{deducing return type for 'f4'}}
}
decltype(auto) f5() {
return i;
return void(); // expected-error {{'decltype(auto)' in return type deduced as 'void' here but deduced as 'int' in earlier return statement}}
+ // expected-note@-3 {{deducing return type for 'f5'}}
}
auto l1 = []() -> decltype(auto) { };
@@ -56,10 +60,12 @@
auto l4 = []() -> decltype(auto) {
return i;
return; // expected-error {{'decltype(auto)' in return type deduced as 'void' here but deduced as 'int' in earlier return statement}}
+ // expected-note@-3 {{deducing return type for 'operator()'}}
};
auto l5 = []() -> decltype(auto) {
return i;
return void(); // expected-error {{'decltype(auto)' in return type deduced as 'void' here but deduced as 'int' in earlier return statement}}
+ // expected-note@-3 {{deducing return type for 'operator()'}}
};
} // namespace DecltypeAuto
@@ -69,33 +75,41 @@
auto *f1() { } // expected-error {{cannot deduce return type 'auto *' for function with no return statements}}
auto *f2() {
return; // expected-error {{cannot deduce return type 'auto *' from omitted return expression}}
+ // expected-note@-2 {{deducing return type for 'f2'}}
}
auto *f3() {
return void(); // expected-error {{cannot deduce return type 'auto *' from returned value of type 'void'}}
+ // expected-note@-2 {{deducing return type for 'f3'}}
}
auto *f4() {
return &i;
return; // expected-error {{cannot deduce return type 'auto *' from omitted return expression}}
+ // expected-note@-3 {{deducing return type for 'f4'}}
}
auto *f5() {
return &i;
return void(); // expected-error {{cannot deduce return type 'auto *' from returned value of type 'void'}}
+ // expected-note@-3 {{deducing return type for 'f5'}}
}
auto l1 = []() -> auto* { }; // expected-error {{cannot deduce return type 'auto *' for function with no return statements}}
auto l2 = []() -> auto* {
return; // expected-error {{cannot deduce return type 'auto *' from omitted return expression}}
+ // expected-note@-2 {{deducing return type for 'operator()'}}
};
auto l3 = []() -> auto* {
return void(); // expected-error {{cannot deduce return type 'auto *' from returned value of type 'void'}}
+ // expected-note@-2 {{deducing return type for 'operator()'}}
};
auto l4 = []() -> auto* {
return &i;
return; // expected-error {{cannot deduce return type 'auto *' from omitted return expression}}
+ // expected-note@-3 {{deducing return type for 'operator()'}}
};
auto l5 = []() -> auto* {
return &i;
return void(); // expected-error {{cannot deduce return type 'auto *' from returned value of type 'void'}}
+ // expected-note@-3 {{deducing return type for 'operator()'}}
};
} // namespace AutoPtr
@@ -105,32 +119,39 @@
}
auto& f2() {
return; // expected-error {{cannot deduce return type 'auto &' from omitted return expression}}
+ // expected-note@-2 {{deducing return type for 'f2'}}
}
auto& f3() {
return void(); // expected-error@-1 {{cannot form a reference to 'void'}}
+ // expected-note@-2 {{deducing return type for 'f3'}}
}
auto& f4() {
return i;
return; // expected-error {{cannot deduce return type 'auto &' from omitted return expression}}
+ // expected-note@-3 {{deducing return type for 'f4'}}
}
auto& f5() {
return i;
return void(); // expected-error@-2 {{cannot form a reference to 'void'}}
+ // expected-note@-3 {{deducing return type for 'f5'}}
}
auto& f6() { return 42; } // expected-error {{non-const lvalue reference to type 'int' cannot bind to a temporary of type 'int'}}
auto l1 = []() -> auto& { }; // expected-error {{cannot deduce return type 'auto &' for function with no return statements}}
auto l2 = []() -> auto& {
return; // expected-error {{cannot deduce return type 'auto &' from omitted return expression}}
+ // expected-note@-2 {{deducing return type for 'operator()'}}
};
auto l3 = []() -> auto& { // expected-error {{cannot form a reference to 'void'}}
+ // expected-note@-1 {{deducing return type for 'operator()'}}
return void();
};
-auto l4 = []() -> auto& {
+auto l4 = []() -> auto& { // expected-note {{deducing return type for 'operator()'}}
return i;
return; // expected-error {{cannot deduce return type 'auto &' from omitted return expression}}
};
auto l5 = []() -> auto& { // expected-error {{cannot form a reference to 'void'}}
+ // expected-note@-1 {{deducing return type for 'operator()'}}
return i;
return void();
};
Index: clang/test/SemaCXX/typo-correction-crash.cpp
===================================================================
--- clang/test/SemaCXX/typo-correction-crash.cpp
+++ clang/test/SemaCXX/typo-correction-crash.cpp
@@ -9,6 +9,7 @@
return "s";
return tes; // expected-error {{use of undeclared identifier 'tes'; did you mean 'test'?}}
// expected-error@-1 {{deduced as 'int' here but deduced as 'const char *' in earlier}}
+ // expected-note@-4 {{deducing return type for 'check2'}}
}
template <class A, class B> struct is_same { static constexpr bool value = false; };
Index: clang/test/SemaTemplate/concepts.cpp
===================================================================
--- clang/test/SemaTemplate/concepts.cpp
+++ clang/test/SemaTemplate/concepts.cpp
@@ -114,6 +114,7 @@
}
template<typename ...T> void g5() {
([]() -> C<T> auto{ // expected-error-re {{deduced type {{.*}} does not satisfy}}
+ // expected-note@-1 {{deducing return type for 'operator()'}}
return T();
}(), ...);
}
@@ -174,26 +175,34 @@
template<class T> concept C = false; // expected-note 6 {{because 'false' evaluated to false}}
C auto f1() { // expected-error {{deduced type 'void' does not satisfy 'C'}}
+ // expected-note@-1 {{deducing return type for 'f1'}}
return void();
}
C auto f2() { // expected-error {{deduced type 'void' does not satisfy 'C'}}
+ // expected-note@-1 {{deducing return type for 'f2'}}
return;
}
C auto f3() { // expected-error {{deduced type 'void' does not satisfy 'C'}}
+ // expected-note@-1 {{deducing return type for 'f3'}}
}
C decltype(auto) f4() { // expected-error {{deduced type 'void' does not satisfy 'C'}}
+ // expected-note@-1 {{deducing return type for 'f4'}}
return void();
}
C decltype(auto) f5() { // expected-error {{deduced type 'void' does not satisfy 'C'}}
+ // expected-note@-1 {{deducing return type for 'f5'}}
return;
}
C decltype(auto) f6() { // expected-error {{deduced type 'void' does not satisfy 'C'}}
+ // expected-note@-1 {{deducing return type for 'f6'}}
}
C auto& f7() { // expected-error {{cannot form a reference to 'void'}}
+ // expected-note@-1 {{deducing return type for 'f7'}}
return void();
}
C auto& f8() {
return; // expected-error {{cannot deduce return type 'C auto &' from omitted return expression}}
+ // expected-note@-2 {{deducing return type for 'f8'}}
}
C auto& f9() { // expected-error {{cannot deduce return type 'C auto &' for function with no return statements}}
}