[cfe-dev] SourceRange for an extern template declaration

[Richard Smith]

On Tue, Aug 12, 2014 at 8:54 AM, Eli Bendersky <eliben at google.com> wrote:

> Hello,
>
> We may be observing an invalid SourceRange being attached to an extern
> template declaration. Consider this code:
>
>   template <typename T>
>   int __ostream_insert() {
>     return 0;
>   }
>
>   extern template int __ostream_insert<char>();
>
>   template<> int __ostream_insert<long>() {
>     return 1;
>   }
>
> The AST dump for it is:
>
>     TranslationUnitDecl 0x3763300 <<invalid sloc>> <invalid sloc>
>     |-TypedefDecl 0x3763840 <<invalid sloc>> <invalid sloc> implicit
> __int128_t '__int128'
>     |-TypedefDecl 0x37638a0 <<invalid sloc>> <invalid sloc> implicit
> __uint128_t 'unsigned __int128'
>     |-TypedefDecl 0x3763c60 <<invalid sloc>> <invalid sloc> implicit
> __builtin_va_list '__va_list_tag [1]'
>     |-FunctionTemplateDecl 0x3763e50 </tmp/jp.cpp:1:3, line:4:3> line:2:7
> __ostream_insert
>     | |-TemplateTypeParmDecl 0x3763cb0 <line:1:13, col:22> col:22 typename
> T
>     | |-FunctionDecl 0x3763db0 <line:2:3, line:4:3> line:2:7
> __ostream_insert 'int (void)'
>     | | `-CompoundStmt 0x3763ed8 <col:26, line:4:3>
>     | |   `-ReturnStmt 0x3763eb8 <line:3:5, col:12>
>     | |     `-IntegerLiteral 0x3763e98 <col:12> 'int' 0
>     | |-FunctionDecl 0x37a4f60 <line:2:3, line:4:3> line:2:7
> __ostream_insert 'int (void)'
>     | | `-TemplateArgument type 'char'
>     | `-Function 0x37a50a0 '__ostream_insert' 'int (void)'
>     `-FunctionDecl 0x37a50a0 prev 0x37a51c0 <line:8:3, line:10:3>
> line:8:18 __ostream_insert 'int (void)'
>       |-TemplateArgument type 'long'
>       `-CompoundStmt 0x37a5380 <col:43, line:10:3>
>         `-ReturnStmt 0x37a5360 <line:9:5, col:12>
>           `-IntegerLiteral 0x37a5340 <col:12> 'int' 1
>
>
> Note that the node representing the extern declaration has the source
> range of the original template. Is this a (known) bug, or am I
> misunderstanding something?
>

This is certainly a bug. Note that we don't have a declaration of
__ostream_insert<char> lexically within the TU either; we don't create any
explicit representation of it. See this FIXME:

http://clang.llvm.org/doxygen/SemaTemplate_8cpp_source.html#l07688
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20140812/9d22b812/attachment.html>