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[Clang][Sema] Convert warning for extraneous template parameter lists to an extension warning (#82277)
We currently accept the following explicit specialization with a warning for the extraneous template parameter list: ``` template<typename T> void f(); template<> template<> void f<int>(); // warning: extraneous template parameter list in template specialization ``` This should really be an extension warning so we reject with `-pedantic-errors`. This patch converts the warning to an extension warning.
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-14
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7 files changed

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-14
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‎clang/docs/ReleaseNotes.rst‎

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@@ -209,6 +209,8 @@ Improvements to Clang's diagnostics
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`WG14 N3029 <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3029.htm>`_.
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Fixes `#69352 <https://github.com/llvm/llvm-project/issues/69352>`_.
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- Clang now diagnoses extraneous template parameter lists as a language extension.
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Improvements to Clang's time-trace
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----------------------------------
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‎clang/include/clang/Basic/DiagnosticSemaKinds.td‎

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@@ -5325,7 +5325,7 @@ def err_alias_template_extra_headers : Error<
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def err_template_spec_extra_headers : Error<
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"extraneous template parameter list in template specialization or "
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"out-of-line template definition">;
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def warn_template_spec_extra_headers : Warning<
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def ext_template_spec_extra_headers : ExtWarn<
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"extraneous template parameter list in template specialization">;
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def note_explicit_template_spec_does_not_need_header : Note<
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"'template<>' header not required for explicitly-specialized class %0 "

‎clang/lib/Sema/SemaTemplate.cpp‎

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@@ -3667,7 +3667,7 @@ TemplateParameterList *Sema::MatchTemplateParametersToScopeSpecifier(
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if (!SuppressDiagnostic)
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Diag(ParamLists[ParamIdx]->getTemplateLoc(),
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AllExplicitSpecHeaders ? diag::warn_template_spec_extra_headers
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AllExplicitSpecHeaders ? diag::ext_template_spec_extra_headers
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: diag::err_template_spec_extra_headers)
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<< SourceRange(ParamLists[ParamIdx]->getTemplateLoc(),
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ParamLists[ParamLists.size() - 2]->getRAngleLoc());

‎clang/test/CXX/dcl.decl/dcl.meaning/dcl.fct/p23.cpp‎

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Original file line numberDiff line numberDiff line change
@@ -1,7 +1,6 @@
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// RUN: %clang_cc1 -std=c++20 -pedantic-errors -verify %s
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3-
// FIXME: This should be an error with -pedantic-errors.
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template<> // expected-warning {{extraneous template parameter list in template specialization}}
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template<> // expected-error {{extraneous template parameter list in template specialization}}
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void f(auto);
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template<typename>
@@ -18,7 +17,6 @@ void A<T>::g(auto) { }
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template<>
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void A<int>::g(auto) { }
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// FIXME: This should be an error with -pedantic-errors.
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template<>
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template<> // expected-warning {{extraneous template parameter list in template specialization}}
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template<> // expected-error {{extraneous template parameter list in template specialization}}
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void A<long>::g(auto) { }

‎clang/test/CXX/drs/dr5xx.cpp‎

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Original file line numberDiff line numberDiff line change
@@ -354,17 +354,15 @@ namespace dr531 { // dr531: partial
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template<> void A<char>::f(char) {}
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// expected-error@-1 {{no function template matches function template specialization 'f'}}
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// FIXME: This is ill-formed; -pedantic-errors should reject.
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template<> template<typename U> void A<char>::g(char, U) {}
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// expected-warning@-1 {{extraneous template parameter list in template specialization}}
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// expected-error@-1 {{extraneous template parameter list in template specialization}}
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// expected-note@#dr531-A-char {{'template<>' header not required for explicitly-specialized class 'dr531::bad::A<char>' declared here}}
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template<> struct A<char>::B {};
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// expected-error@-1 {{extraneous 'template<>' in declaration of struct 'B'}}
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// expected-error@-2 {{specialization of member 'dr531::bad::A<char>::B' does not specialize an instantiated member}}
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// expected-note@#dr531-B {{attempt to specialize declaration here}}
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// FIXME: This is ill-formed; -pedantic-errors should reject.
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template<> template<typename U> struct A<char>::C {};
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// expected-warning@-1 {{extraneous template parameter list in template specialization}}
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// expected-error@-1 {{extraneous template parameter list in template specialization}}
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// expected-note@#dr531-A-char {{'template<>' header not required for explicitly-specialized class 'dr531::bad::A<char>' declared here}}
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template<> char A<char>::n = 0;
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// expected-error@-1 {{extraneous 'template<>' in declaration of variable 'n'}}
@@ -808,7 +806,7 @@ namespace dr571 { // dr571 unknown
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int n;
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// FIXME: Test if this has internal linkage.
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const ir r = n;
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// expected-warning@-1 {{'const' qualifier on reference type 'ir' (aka 'int &') has no effect}}
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// expected-warning@-1 {{'const' qualifier on reference type 'ir' (aka 'int &') has no effect}}
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}
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namespace dr572 { // dr572: yes
@@ -990,7 +988,7 @@ namespace dr580 { // dr580: partial
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// FIXME: We incorrectly accept this
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// because we think C2::Y::A<...> might
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// instantiate to C2::X::A
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template<X::I> struct A {};
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template<X::I> struct A {};
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};
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};
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‎clang/test/CXX/temp/temp.spec/temp.expl.spec/p16.cpp‎

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@@ -1,4 +1,4 @@
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// RUN: %clang_cc1 -fsyntax-only -verify %s
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// RUN: %clang_cc1 -fsyntax-only -pedantic-errors -verify %s
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template<class T> struct A {
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void f(T);
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template<class X1> void g1(T, X1);
@@ -36,3 +36,97 @@ namespace PR10024 {
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template <>
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void Test<T>::get<double>(double i) {} // expected-error{{cannot specialize (with 'template<>') a member of an unspecialized template}}
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}
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namespace extraneous {
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template<typename T> struct A;
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template<typename T> int x;
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template<typename T> void f();
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template<> // expected-error{{extraneous template parameter list in template specialization}}
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template<>
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struct A<int>;
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template<> // expected-error{{extraneous template parameter list in template specialization}}
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template<>
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int x<int>;
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template<> // expected-error{{extraneous template parameter list in template specialization}}
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template<>
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void f<int>();
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template<typename T>
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struct B {
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struct C;
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template<typename U>
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struct D;
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static int y;
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template<typename U>
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static int z;
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void g();
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template<typename U>
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void h();
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enum class E;
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enum F : int;
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};
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template<>
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template<> // expected-error{{extraneous 'template<>' in declaration of struct 'C'}}
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struct B<int>::C;
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template<>
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template<> // expected-error{{extraneous template parameter list in template specialization}}
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template<>
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struct B<int>::D<int>;
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template<>
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template<> // expected-error{{extraneous template parameter list in template specialization}}
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template<typename U>
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struct B<int>::D;
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template<>
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template<> // expected-error{{extraneous 'template<>' in declaration of variable 'y'}}
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int B<int>::y;
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template<>
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template<> // expected-error{{extraneous template parameter list in template specialization}}
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template<>
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int B<int>::z<int>;
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template<>
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template<> // expected-error{{extraneous template parameter list in template specialization}}
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template<typename U>
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int B<int>::z;
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template<>
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template<>
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void B<int>::g(); // expected-error{{no function template matches function template specialization 'g'}}
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template<>
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template<> // expected-error{{extraneous template parameter list in template specialization}}
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template<>
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void B<int>::h<int>();
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template<>
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template<> // expected-error{{extraneous template parameter list in template specialization}}
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template<typename U>
121+
void B<int>::h<int>(); // expected-error{{function template partial specialization is not allowed}}
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123+
// FIXME: We should diagnose this as having an extraneous 'template<>'
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template<>
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template<>
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enum class B<int>::E; // expected-error{{enumeration cannot be a template}}
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128+
// FIXME: We should diagnose this as having an extraneous 'template<>'
129+
template<>
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template<>
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enum B<int>::F : int; // expected-error{{enumeration cannot be a template}}
132+
}

‎clang/test/Misc/warning-flags.c‎

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@@ -26,6 +26,7 @@ CHECK-NEXT: ext_missing_whitespace_after_macro_name
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CHECK-NEXT: ext_new_paren_array_nonconst
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CHECK-NEXT: ext_plain_complex
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CHECK-NEXT: ext_template_arg_extra_parens
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CHECK-NEXT: ext_template_spec_extra_headers
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CHECK-NEXT: ext_typecheck_cond_incompatible_operands
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CHECK-NEXT: ext_typecheck_ordered_comparison_of_pointer_integer
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CHECK-NEXT: ext_using_undefined_std
@@ -78,7 +79,6 @@ CHECK-NEXT: warn_register_objc_catch_parm
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CHECK-NEXT: warn_related_result_type_compatibility_class
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CHECK-NEXT: warn_related_result_type_compatibility_protocol
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CHECK-NEXT: warn_template_export_unsupported
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CHECK-NEXT: warn_template_spec_extra_headers
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CHECK-NEXT: warn_tentative_incomplete_array
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CHECK-NEXT: warn_typecheck_function_qualifiers
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CHECK-NEXT: warn_undef_interface

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