使用 clang 解析命名空间:在另一个源文件中包含标头或直接解析标头时，AST 差异

很抱歉这个问题很冗长，但我看不出任何其他方法可以说清楚。 我正在编写一个工具，用于将C++头文件转换为 SWIG 接口文件，作为进一步微调的入门。

在这样做的过程中，我注意到 clang (v3.0( 的一些奇怪行为。 如果我解析头文件，得到的 AST 与解析包含头文件的源文件明显不同。

为了便于说明，下面是一些示例源文件：

源文件：

// example.cpp: Test case for nsbug.py
//
#include "example.h"

页眉：

// example.h: Test case for nsbug.py
//
namespace Geom {
struct Location
{
    double x, y;
};
class Shape
{
public:
    Shape();
    void set_location(const Location &where)
    {
        m_pos = where;
    };
    const Location &get_location() const
    // Draw it...
    virtual void draw() const = 0;
protected:
    Location m_pos;
};
class Circle : public Shape
{
    Circle();
    virtual void draw() const;
};
} // namespace Geom

我使用以下 Python 代码来解析它并转储 AST：

# Usage: python nsbug.py <file>
import sys
import clang.cindex
def indent(level):
    """ Indentation string for pretty-printing
    """ 
    return '  '*level
def output_cursor(cursor, level):
    """ Low level cursor output
    """
    spelling = ''
    displayname = ''
    if cursor.spelling:
        spelling = cursor.spelling
    if cursor.displayname:
        displayname = cursor.displayname
    kind = cursor.kind;
    print indent(level) + spelling, '<' + str(kind) + '>'
    print indent(level+1) + '"'  + displayname + '"'
def output_cursor_and_children(cursor, level=0):
    """ Output this cursor and its children with minimal formatting.
    """
    output_cursor(cursor, level)
    if cursor.kind.is_reference():
        print indent(level) + 'reference to:'
        output_cursor(clang.cindex.Cursor_ref(cursor), level+1)
    # Recurse for children of this cursor
    has_children = False;
    for c in cursor.get_children():
        if not has_children:
            print indent(level) + '{'
            has_children = True
        output_cursor_and_children(c, level+1)
    if has_children:
        print indent(level) + '}'
index = clang.cindex.Index.create()
tu = index.parse(sys.argv[1], options=1)
output_cursor_and_children(tu.cursor)

当我在示例中运行它时.cpp我得到(我认为是正确的(：

 <CursorKind.TRANSLATION_UNIT>
  "example.cpp"
{
  (Deleted lots of clang-generated declarations such as __VERSION__)
  Geom <CursorKind.NAMESPACE>
    "Geom"
  {
    Location <CursorKind.STRUCT_DECL>
      "Location"
    {
      x <CursorKind.FIELD_DECL>
        "x"
      y <CursorKind.FIELD_DECL>
        "y"
    }
    Shape <CursorKind.CLASS_DECL>
      "Shape"
    {
       <CursorKind.CXX_ACCESS_SPEC_DECL>
        ""
       <CursorKind.CXX_ACCESS_SPEC_DECL>
        ""
      Shape <CursorKind.CONSTRUCTOR>
        "Shape()"
      set_location <CursorKind.CXX_METHOD>
        "set_location(const Geom::Location &)"
      {
        where <CursorKind.PARM_DECL>
          "where"
        {
           <CursorKind.TYPE_REF>
            "struct Geom::Location"
          reference to:
            Location <CursorKind.STRUCT_DECL>
              "Location"
        }
         <CursorKind.COMPOUND_STMT>
          ""
        {
           <CursorKind.CALL_EXPR>
            "operator="
          {
             <CursorKind.MEMBER_REF_EXPR>
              "m_pos"
             <CursorKind.UNEXPOSED_EXPR>
              "operator="
            {
               <CursorKind.DECL_REF_EXPR>
                "operator="
            }
             <CursorKind.DECL_REF_EXPR>
              "where"
          }
        }
      }
      get_location <CursorKind.CXX_METHOD>
        "get_location()"
      {
         <CursorKind.TYPE_REF>
          "struct Geom::Location"
        reference to:
          Location <CursorKind.STRUCT_DECL>
            "Location"
      }
       <CursorKind.CXX_ACCESS_SPEC_DECL>
        ""
       <CursorKind.CXX_ACCESS_SPEC_DECL>
        ""
      m_pos <CursorKind.FIELD_DECL>
        "m_pos"
      {
         <CursorKind.TYPE_REF>
          "struct Geom::Location"
        reference to:
          Location <CursorKind.STRUCT_DECL>
            "Location"
      }
    }
    Circle <CursorKind.CLASS_DECL>
      "Circle"
    {
       <CursorKind.CXX_BASE_SPECIFIER>
        "class Geom::Shape"
      reference to:
        Shape <CursorKind.CLASS_DECL>
          "Shape"
      {
         <CursorKind.TYPE_REF>
          "class Geom::Shape"
        reference to:
          Shape <CursorKind.CLASS_DECL>
            "Shape"
      }
      Circle <CursorKind.CONSTRUCTOR>
        "Circle()"
      draw <CursorKind.CXX_METHOD>
        "draw()"
    }
  }
}

但是当我在头文件上尝试使用它时python nsbug.py example.py我只得到：

 <CursorKind.TRANSLATION_UNIT>
  "example.h"
{
  (deleted lots of clang-generated definitions such as __VERSION__)
  Geom <CursorKind.VAR_DECL>
    "Geom"
}

为什么 AST 中的Geom名称空间是VAR_DECL？ 我本来期望没有区别，除了预处理器游标。

解决方法是显而易见的 - 只需在内存中创建一个包含标头的临时文件 - 但这不是很令人满意。 有人可以开导我吗？