[cfe-commits] r153887 - in /cfe/trunk: include/clang/Basic/DiagnosticParseKinds.td lib/Parse/ParseTemplate.cpp test/FixIt/fixit.cpp test/Parser/cxx-template-decl.cpp

[Douglas Gregor]

On Apr 2, 2012, at 12:15 PM, David Blaikie wrote:

> Author: dblaikie
> Date: Mon Apr  2 14:15:28 2012
> New Revision: 153887
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=153887&view=rev
> Log:
> Correct error recovery when missing 'class' in a template template parameter.
> 
> The diagnostic message correctly informs the user that they have omitted the
> 'class' keyword, but neither suggests this insertion as a fixit, nor attempts
> to recover as if they had provided the keyword.
> 
> This fixes the recovery, adds the fixit, and adds a separate diagnostic and
> corresponding replacement fixit for cases where the user wrote 'struct' or
> 'typename' instead of 'class' (suggested by Richard Smith as a possible common
> mistake).
> 
> I'm not sure the diagnostic message for either the original or new cases feel
> very Clang-esque, so I'm open to suggestions there. The fixit hints make it
> fairly easy to see what's required, though.
> 
> Modified:
>    cfe/trunk/include/clang/Basic/DiagnosticParseKinds.td
>    cfe/trunk/lib/Parse/ParseTemplate.cpp
>    cfe/trunk/test/FixIt/fixit.cpp
>    cfe/trunk/test/Parser/cxx-template-decl.cpp
> 
> Modified: cfe/trunk/include/clang/Basic/DiagnosticParseKinds.td
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticParseKinds.td?rev=153887&r1=153886&r2=153887&view=diff
> ==============================================================================
> --- cfe/trunk/include/clang/Basic/DiagnosticParseKinds.td (original)
> +++ cfe/trunk/include/clang/Basic/DiagnosticParseKinds.td Mon Apr  2 14:15:28 2012
> @@ -480,6 +480,7 @@
> def err_expected_comma_greater : Error<
>   "expected ',' or '>' in template-parameter-list">;
> def err_expected_class_before : Error<"expected 'class' before '%0'">;
> +def err_expected_class_instead : Error<"expected 'class' instead of '%0'">;
> def err_template_spec_syntax_non_template : Error<
>   "identifier followed by '<' indicates a class template specialization but "
>   "%0 %select{does not refer to a template|refers to a function "
> 
> Modified: cfe/trunk/lib/Parse/ParseTemplate.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Parse/ParseTemplate.cpp?rev=153887&r1=153886&r2=153887&view=diff
> ==============================================================================
> --- cfe/trunk/lib/Parse/ParseTemplate.cpp (original)
> +++ cfe/trunk/lib/Parse/ParseTemplate.cpp Mon Apr  2 14:15:28 2012
> @@ -540,12 +540,17 @@
> 
>   // Generate a meaningful error if the user forgot to put class before the
>   // identifier, comma, or greater.
> -  if (!Tok.is(tok::kw_class)) {
> -    Diag(Tok.getLocation(), diag::err_expected_class_before)
> -      << PP.getSpelling(Tok);
> -    return 0;
> -  }
> -  ConsumeToken();
> +  if (Tok.is(tok::kw_typename) || Tok.is(tok::kw_struct)) {
> +    Diag(Tok.getLocation(), diag::err_expected_class_instead)
> +      << PP.getSpelling(Tok)
> +      << FixItHint::CreateReplacement(Tok.getLocation(), "class");
> +    ConsumeToken();
> +  } else if (!Tok.is(tok::kw_class))
> +      Diag(Tok.getLocation(), diag::err_expected_class_before)
> +        << PP.getSpelling(Tok)
> +        << FixItHint::CreateInsertion(Tok.getLocation(), "class ");

This seems overly eager in providing a Fix-It. Shouldn't we check that the next token is something that actually makes sense for a template template parameter, e.g., '…', an identifier, a ',', '>', or '>>'?

> +  else 
> +    ConsumeToken();
> 
>   // Parse the ellipsis, if given.
>   SourceLocation EllipsisLoc;
> 
> Modified: cfe/trunk/test/FixIt/fixit.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/FixIt/fixit.cpp?rev=153887&r1=153886&r2=153887&view=diff
> ==============================================================================
> --- cfe/trunk/test/FixIt/fixit.cpp (original)
> +++ cfe/trunk/test/FixIt/fixit.cpp Mon Apr  2 14:15:28 2012
> @@ -199,3 +199,8 @@
>   expected-error {{missing 'typename' prior to dependent}}
>   return Mystery<T>::get();
> }
> +
> +template<template<typename> Foo, // expected-error {{expected 'class' before 'Foo'}}
> +         template<typename> typename Bar, // expected-error {{expected 'class' instead of 'typename'}}
> +         template<typename> struct Baz> // expected-error {{expected 'class' instead of 'struct'}}
> +void func();
> 
> Modified: cfe/trunk/test/Parser/cxx-template-decl.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Parser/cxx-template-decl.cpp?rev=153887&r1=153886&r2=153887&view=diff
> ==============================================================================
> --- cfe/trunk/test/Parser/cxx-template-decl.cpp (original)
> +++ cfe/trunk/test/Parser/cxx-template-decl.cpp Mon Apr  2 14:15:28 2012
> @@ -11,10 +11,8 @@
> // expected-warning {{declaration does not declare anything}}
> template <template X> struct Err1; // expected-error {{expected '<' after 'template'}} \
> // expected-error{{extraneous}}
> -template <template <typename> > struct Err2;       // expected-error {{expected 'class' before '>'}} \
> -// expected-error{{extraneous}}
> -template <template <typename> Foo> struct Err3;    // expected-error {{expected 'class' before 'Foo'}} \
> -// expected-error{{extraneous}}
> +template <template <typename> > struct Err2;       // expected-error {{expected 'class' before '>'}}
> +template <template <typename> Foo> struct Err3;    // expected-error {{expected 'class' before 'Foo'}}
> 
> // Template function declarations
> template <typename T> void foo();
> 
> 
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