r193144 - Sema: Do not allow template declarations inside local classes

Howard Hinnant hhinnant at apple.com
Tue Oct 22 09:49:41 PDT 2013


Thanks, fix committed revision 193169.

Howard

On Oct 22, 2013, at 10:08 AM, David Majnemer <david.majnemer at gmail.com> wrote:

> Yep, looks like libcxxabi violates 14.5.2 [temp.mem]/p2. Looks like this violation was introduced back in r184097. Note that trying to compile with GCC gets us a similar error:
> invalid declaration of member template in local class
> 
> CC'ing Howard Hinnant.
> 
> 
> On Tue, Oct 22, 2013 at 4:36 AM, İsmail Dönmez <ismail at donmez.ws> wrote:
> This breaks libc++abi:
> 
> [   52s] + clang++ -c -g -O3 -fPIC -std=c++11 -stdlib=libc++ -fstrict-aliasing -Wstrict-aliasing=2 -Wsign-conversion -Wshadow -Wconversion -Wunused-variable -Wmissing-field-initializers -Wchar-subscripts -Wmismatched-tags -Wmissing-braces -Wshorten-64-to-32 -Wsign-compare -Wstrict-aliasing=2 -Wstrict-overflow=4 -Wunused-parameter -Wnewline-eof -I../include ../src/cxa_demangle.cpp
> [   53s] ../src/cxa_demangle.cpp:4624:9: error: templates cannot be declared inside of a local class
> [   53s]         template <size_t N>
> [   53s]         ^~~~~~~~~~~~~~~~~~~
> [   53s] ../src/cxa_demangle.cpp:4631:8: error: no matching constructor for initialization of 'Db'
> [   53s]     Db db(a);
> [   53s]        ^  ~
> [   53s] ../src/cxa_demangle.cpp:4609:12: note: candidate constructor (the implicit move constructor) not viable: no known conversion from 'arena<bs>' to 'Db' for 1st argument
> [   53s]     struct Db
> [   53s]            ^
> [   53s] ../src/cxa_demangle.cpp:4609:12: note: candidate constructor (the implicit copy constructor) not viable: no known conversion from 'arena<bs>' to 'const Db' for 1st argument
> [   53s]     struct Db
> [   53s]            ^
> [   53s] ../src/cxa_demangle.cpp:4609:12: note: candidate constructor (the implicit default constructor) not viable: requires 0 arguments, but 1 was provided
> 
> 
> On Tue, Oct 22, 2013 at 7:14 AM, David Majnemer <david.majnemer at gmail.com> wrote:
> Author: majnemer
> Date: Mon Oct 21 23:14:18 2013
> New Revision: 193144
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=193144&view=rev
> Log:
> Sema: Do not allow template declarations inside local classes
> 
> Summary:
> Enforce the rule in C++11 [temp.mem]p2 that local classes cannot have
> member templates.
> 
> This fixes PR16947.
> 
> N.B.  C++14 has slightly different wording to afford generic lambdas
> declared inside of functions.
> 
> Fun fact:  Some formulations of local classes with member templates
> would cause clang to crash during Itanium mangling, such as the
> following:
> 
> void outer_mem() {
>   struct Inner {
>     template <typename = void>
>     struct InnerTemplateClass {
>       static void itc_mem() {}
>     };
>   };
>   Inner::InnerTemplateClass<>::itc_mem();
> }
> 
> Reviewers: eli.friedman, rsmith, doug.gregor, faisalv
> 
> Reviewed By: doug.gregor
> 
> CC: cfe-commits, ygao
> 
> Differential Revision: http://llvm-reviews.chandlerc.com/D1866
> 
> Added:
>     cfe/trunk/test/CXX/temp/temp.decls/temp.mem/p2.cpp
> Removed:
>     cfe/trunk/test/PCH/cxx-local-templates.cpp
>     cfe/trunk/test/PCH/cxx1y-local-templates.cpp
>     cfe/trunk/test/SemaTemplate/local-member-templates.cpp
> Modified:
>     cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
>     cfe/trunk/lib/Sema/SemaTemplate.cpp
>     cfe/trunk/test/CodeGenCXX/mangle-local-class-names.cpp
>     cfe/trunk/test/SemaTemplate/instantiate-exception-spec-cxx11.cpp
> 
> Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=193144&r1=193143&r2=193144&view=diff
> ==============================================================================
> --- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
> +++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Mon Oct 21 23:14:18 2013
> @@ -2835,6 +2835,8 @@ def warn_template_export_unsupported : W
>    "exported templates are unsupported">;
>  def err_template_outside_namespace_or_class_scope : Error<
>    "templates can only be declared in namespace or class scope">;
> +def err_template_inside_local_class : Error<
> +  "templates cannot be declared inside of a local class">;
>  def err_template_linkage : Error<"templates must have C++ linkage">;
>  def err_template_typedef : Error<"a typedef cannot be a template">;
>  def err_template_unnamed_class : Error<
> 
> Modified: cfe/trunk/lib/Sema/SemaTemplate.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaTemplate.cpp?rev=193144&r1=193143&r2=193144&view=diff
> ==============================================================================
> --- cfe/trunk/lib/Sema/SemaTemplate.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaTemplate.cpp Mon Oct 21 23:14:18 2013
> @@ -5459,8 +5459,20 @@ Sema::CheckTemplateDeclScope(Scope *S, T
>    while (Ctx && isa<LinkageSpecDecl>(Ctx))
>      Ctx = Ctx->getParent();
> 
> -  if (Ctx && (Ctx->isFileContext() || Ctx->isRecord()))
> -    return false;
> +  if (Ctx) {
> +    if (Ctx->isFileContext())
> +      return false;
> +    if (CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(Ctx)) {
> +      // C++ [temp.mem]p2:
> +      //   A local class shall not have member templates.
> +      if (RD->isLocalClass())
> +        return Diag(TemplateParams->getTemplateLoc(),
> +                    diag::err_template_inside_local_class)
> +          << TemplateParams->getSourceRange();
> +      else
> +        return false;
> +    }
> +  }
> 
>    return Diag(TemplateParams->getTemplateLoc(),
>                diag::err_template_outside_namespace_or_class_scope)
> 
> Added: cfe/trunk/test/CXX/temp/temp.decls/temp.mem/p2.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CXX/temp/temp.decls/temp.mem/p2.cpp?rev=193144&view=auto
> ==============================================================================
> --- cfe/trunk/test/CXX/temp/temp.decls/temp.mem/p2.cpp (added)
> +++ cfe/trunk/test/CXX/temp/temp.decls/temp.mem/p2.cpp Mon Oct 21 23:14:18 2013
> @@ -0,0 +1,12 @@
> +// RUN: %clang_cc1 -fsyntax-only -verify %s
> +
> +template <typename>
> +void quux();
> +
> +void fun() {
> +  struct foo {
> +    template <typename> struct bar {};  // expected-error{{templates cannot be declared inside of a local class}}
> +    template <typename> void baz() {}   // expected-error{{templates cannot be declared inside of a local class}}
> +    template <typename> void qux();     // expected-error{{templates cannot be declared inside of a local class}}
> +  };
> +}
> 
> Modified: cfe/trunk/test/CodeGenCXX/mangle-local-class-names.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/mangle-local-class-names.cpp?rev=193144&r1=193143&r2=193144&view=diff
> ==============================================================================
> --- cfe/trunk/test/CodeGenCXX/mangle-local-class-names.cpp (original)
> +++ cfe/trunk/test/CodeGenCXX/mangle-local-class-names.cpp Mon Oct 21 23:14:18 2013
> @@ -75,16 +75,6 @@ inline void OmittingCode(float x) {
>  }
>  void CallOmittingCode() { OmittingCode(1); }
> 
> -// CHECK: @_ZZ25LocalTemplateFunctionTestdEN5Local3fooIdEET_S1_
> -int LocalTemplateFunctionTest(double d) {
> -  struct Local {
> -    template<class T> T foo(T t) {
> -      return t;
> -    }
> -  };
> -  return Local().foo(d);
> -}
> -
>  // CHECK: @_ZZ15LocalAnonStructvENUt0_1gEv
>  inline void LocalAnonStruct() {
>    if (0) {
> 
> Removed: cfe/trunk/test/PCH/cxx-local-templates.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/PCH/cxx-local-templates.cpp?rev=193143&view=auto
> ==============================================================================
> --- cfe/trunk/test/PCH/cxx-local-templates.cpp (original)
> +++ cfe/trunk/test/PCH/cxx-local-templates.cpp (removed)
> @@ -1,55 +0,0 @@
> -// RUN: %clang_cc1 -pedantic-errors -std=c++11 -emit-pch %s -o %t-cxx11
> -// RUN: %clang_cc1 -ast-print -pedantic-errors -std=c++11 -include-pch %t-cxx11  %s | FileCheck -check-prefix=CHECK-PRINT %s
> -
> -#ifndef HEADER_INCLUDED
> -
> -#define HEADER_INCLUDED
> -
> -int nontemplate_test(double d) {
> -  struct Local {
> -    template<class T> T foo(T t) {
> -      return t;
> -    }
> -  };
> -  return Local{}.foo(d);
> -}
> -
> -template<class U>
> -U template_test(U d) {
> -  struct Local {
> -    template<class T> T foo(T t) {
> -      return t;
> -    }
> -  };
> -  return Local{}.foo(d);
> -}
> -
> -int nested_local() {
> -  struct Inner1 {
> -    int inner1_foo(char c) {
> -      struct Inner2 {
> -        template<class T> T inner2_foo(T t) {
> -          return t;
> -        }
> -      };
> -      return Inner2{}.inner2_foo(3.14);
> -    }
> -  };
> -  return Inner1{}.inner1_foo('a');
> -}
> -
> -#else
> -
> -// CHECK-PRINT: U template_test
> -
> -// CHECK-PRINT: int nontemplate_test(double)
> -
> -int nontemplate_test(double);
> -
> -template double template_test(double);
> -int test2(int y) {
> -  return nontemplate_test(y) + template_test(y);
> -}
> -
> -
> -#endif
> 
> Removed: cfe/trunk/test/PCH/cxx1y-local-templates.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/PCH/cxx1y-local-templates.cpp?rev=193143&view=auto
> ==============================================================================
> --- cfe/trunk/test/PCH/cxx1y-local-templates.cpp (original)
> +++ cfe/trunk/test/PCH/cxx1y-local-templates.cpp (removed)
> @@ -1,58 +0,0 @@
> -// RUN: %clang_cc1 -pedantic-errors -std=c++1y -emit-pch %s -o %t-cxx1y
> -// RUN: %clang_cc1 -ast-print -pedantic-errors -std=c++1y -include-pch %t-cxx1y  %s | FileCheck -check-prefix=CHECK-PRINT %s
> -
> -#ifndef HEADER_INCLUDED
> -
> -#define HEADER_INCLUDED
> -
> -auto nested_local_call_all() {
> -  struct Inner1 {
> -    auto inner1_foo(char c) {
> -      struct Inner2 {
> -        template<class T> T inner2_foo(T t) {
> -          return t;
> -        }
> -      };
> -      return Inner2{};
> -    }
> -  };
> -  return Inner1{}.inner1_foo('a').inner2_foo(4);
> -}
> -
> -
> -auto nested_local() {
> -  struct Inner1 {
> -    auto inner1_foo(char c) {
> -      struct Inner2 {
> -        template<class T> T inner2_foo(T t) {
> -          return t;
> -        }
> -      };
> -      return Inner2{};
> -    }
> -  };
> -  return Inner1{};
> -}
> -
> -
> -int test() {
> -  auto A = nested_local_call_all();
> -  auto B = nested_local();
> -  auto C = B.inner1_foo('a');
> -  C.inner2_foo(3.14);
> -
> -}
> -
> -
> -#else
> -
> -// CHECK-PRINT: int nested_local_call_all
> -// CHECK-PRINT: nested_local
> -auto nested_local_call_all();
> -
> -int test(int y) {
> -  return nested_local_call_all();
> -}
> -
> -
> -#endif
> 
> Modified: cfe/trunk/test/SemaTemplate/instantiate-exception-spec-cxx11.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaTemplate/instantiate-exception-spec-cxx11.cpp?rev=193144&r1=193143&r2=193144&view=diff
> ==============================================================================
> --- cfe/trunk/test/SemaTemplate/instantiate-exception-spec-cxx11.cpp (original)
> +++ cfe/trunk/test/SemaTemplate/instantiate-exception-spec-cxx11.cpp Mon Oct 21 23:14:18 2013
> @@ -44,13 +44,14 @@ namespace dr1330_example {
>      A<int>().f(42);
>    }
> 
> +  struct S {
> +    template<typename T>
> +    static int f() noexcept(noexcept(A<T>().f("boo!"))) { return 0; } // \
> +    // expected-note {{instantiation of exception spec}}
> +    typedef decltype(f<S>()) X;
> +  };
> +
>    int test2() {
> -    struct S {
> -      template<typename T>
> -      static int f() noexcept(noexcept(A<T>().f("boo!"))) { return 0; } // \
> -      // expected-note {{instantiation of exception spec}}
> -      typedef decltype(f<S>()) X;
> -    };
>      S().f<S>(); // ok
>      S().f<int>(); // expected-note {{instantiation of exception spec}}
>    }
> 
> Removed: cfe/trunk/test/SemaTemplate/local-member-templates.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaTemplate/local-member-templates.cpp?rev=193143&view=auto
> ==============================================================================
> --- cfe/trunk/test/SemaTemplate/local-member-templates.cpp (original)
> +++ cfe/trunk/test/SemaTemplate/local-member-templates.cpp (removed)
> @@ -1,99 +0,0 @@
> -// RUN: %clang_cc1 -std=c++1y -verify %s
> -// RUN: %clang_cc1 -std=c++1y -verify %s -fdelayed-template-parsing
> -
> -namespace nested_local_templates_1 {
> -
> -template <class T> struct Outer {
> -  template <class U> int outer_mem(T t, U u) {
> -    struct Inner {
> -      template <class V> int inner_mem(T t, U u, V v) {
> -        struct InnerInner {
> -          template <class W> int inner_inner_mem(W w, T t, U u, V v) {
> -            return 0;
> -          }
> -        };
> -        InnerInner().inner_inner_mem("abc", t, u, v);
> -        return 0;
> -      }
> -    };
> -    Inner i;
> -    i.inner_mem(t, u, 3.14);
> -    return 0;
> -  }
> -
> -  template <class U> int outer_mem(T t, U *u);
> -};
> -
> -template int Outer<int>::outer_mem(int, char);
> -
> -template <class T> template <class U> int Outer<T>::outer_mem(T t, U *u) {
> -  struct Inner {
> -    template <class V>
> -    int inner_mem(T t, U u, V v) { //expected-note{{candidate function}}
> -      struct InnerInner {
> -        template <class W> int inner_inner_mem(W w, T t, U u, V v) { return 0; }
> -      };
> -      InnerInner().inner_inner_mem("abc", t, u, v);
> -      return 0;
> -    }
> -  };
> -  Inner i;
> -  i.inner_mem(t, U{}, i);
> -  i.inner_mem(t, u, 3.14); //expected-error{{no matching member function for call to 'inner}}
> -  return 0;
> -}
> -
> -template int Outer<int>::outer_mem(int, char *); //expected-note{{in instantiation of function}}
> -
> -} // end ns
> -
> -namespace nested_local_templates_2 {
> -
> -template <class T> struct Outer {
> -  template <class U> void outer_mem(T t, U u) {
> -    struct Inner {
> -      template <class V> struct InnerTemplateClass {
> -        template <class W>
> -        void itc_mem(T t, U u, V v, W w) { //expected-note{{candidate function}}
> -          struct InnerInnerInner {
> -            template <class X> void iii_mem(X x) {}
> -          };
> -          InnerInnerInner i;
> -          i.iii_mem("abc");
> -        }
> -      };
> -    };
> -    Inner i;
> -    typename Inner::template InnerTemplateClass<Inner> ii;
> -    ii.itc_mem(t, u, i, "jim");
> -    ii.itc_mem(t, u, 0, "abd"); //expected-error{{no matching member function}}
> -  }
> -};
> -
> -template void
> -Outer<int>::outer_mem(int, char); //expected-note{{in instantiation of}}
> -
> -}
> -
> -namespace more_nested_local_templates {
> -
> -int test() {
> -  struct Local {
> -    template<class U> void foo(U u) {
> -      struct Inner {
> -        template<class A>
> -        auto operator()(A a, U u2) -> U {
> -          return u2;
> -        };
> -      };
> -      Inner GL;
> -      GL('a', u );
> -      GL(3.14, u );
> -    }
> -  };
> -  Local l;
> -  l.foo("nmabc");
> -  return 0;
> -}
> -int t = test();
> -}
> \ No newline at end of file
> 
> 
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