[cfe-dev] Fwd: AST contains "type-dependent" for non-dependency

[Matthias Gehre via cfe-dev]

Hi everyone,

I don't understand why the AST for

template <int Index> struct B {
  int independent() {
    return x[2];
  }
  std::array<int,3> x;
};

is

|-ClassTemplateDecl 0x27faf20 <line:89:1, line:104:1> line:89:29 B
| |-NonTypeTemplateParmDecl 0x27fae20 <col:11, col:15> col:15 referenced
'int' Index
| |-CXXRecordDecl 0x27fae90 <col:22, line:104:1> line:89:29 struct B
definition
| | |-CXXRecordDecl 0x27fb1b8 <col:22, col:29> col:29 implicit struct B
| | |-CXXMethodDecl 0x27fb2d0 <line:90:3, line:94:3> line:90:7 independent
'int (void)'
| | | `-CompoundStmt 0x27fc430 <col:21, line:94:3>
| | |   `-ReturnStmt 0x27fc418 <line:91:5, col:16>
| | |     `-ArraySubscriptExpr 0x27fc3f0 <col:12, col:16> '<dependent
type>' lvalue
| | |       |-MemberExpr 0x27fc378 <col:12> 'std::array<int, 3>':'struct
std::array<int, 3>' lvalue ->x 0x27fc318
| | |       | `-CXXThisExpr 0x27fc360 <col:12> 'B<Index> *' this
| | |       `-IntegerLiteral 0x27fc3b0 <col:15> 'int' 2

Especially, why do we have the ArraySubscriptExpr '<dependent type>'?

When specializing to B<0>, the ArraySubscriptExpr becomes a
CXXOperatorCallExpr as expected:

| |-ClassTemplateSpecializationDecl 0x27fc610 <line:89:1, line:104:1>
line:89:29 struct B definition
| | |-TemplateArgument integral 0
| | |-CXXRecordDecl 0x27fc878 prev 0x27fc610 <col:22, col:29> col:29
implicit struct B
| | |-CXXMethodDecl 0x27fc908 <line:90:3, line:94:3> line:90:7 used
independent 'int (void)'
| | | `-CompoundStmt 0x2800648 <col:21, line:94:3>
| | |   `-ReturnStmt 0x2800630 <line:91:5, col:16>
| | |     `-ImplicitCastExpr 0x2800618 <col:12, col:16> 'int':'int'
<LValueToRValue>
| | |       `-CXXOperatorCallExpr 0x28005d0 <col:12, col:16> 'int':'int'
lvalue
| | |         |-ImplicitCastExpr 0x28005b8 <col:12, col:16> 'int
&(*)(size_t)' <FunctionToPointerDecay>
| | |         | `-DeclRefExpr 0x2800590 <col:12, col:16> 'int &(size_t)'
lvalue CXXMethod 0x27fb870 'operator[]' 'int &(size_t)'
| | |         |-MemberExpr 0x2800540 <col:12> 'std::array<int, 3>':'struct
std::array<int, 3>' lvalue ->x 0x27fca78
| | |         | `-CXXThisExpr 0x2800528 <col:12> 'struct B<0> *' this
| | |         `-ImplicitCastExpr 0x2800578 <col:14, col:15>
'size_t':'unsigned long' <IntegralCast>
| | |           `-IntegerLiteral 0x27fc3b0 <col:15> 'int' 2

Why is the AST for the template and the specialization different? The
method does not depend on the template parameter.

Thanks for any hints,

Matthias
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20160715/303ef1d0/attachment.html>