[cfe-dev] SourceRange for an extern template declaration

Eli Bendersky eliben at google.com
Tue Aug 12 08:54:42 PDT 2014


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?

Thanks in advance,
Eli
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