Fix #33: Support asm labels on register variables (#94)

* fix(parser): Correctly handle asm attributes on register variables

Adds support for `asm` attributes on `register` variables by allowing `asm` and `attributes` to be added to `TypeDeclExt` and `ArrayDeclExt` nodes.

This was preventing the parser from attaching `asm` labels to declarations with storage-class specifiers like `register`.

A new test case, `test_register_asm_label`, is added to verify that declarations like `register int my_var asm("my_reg");` are now parsed correctly.

* test: Add comprehensive round-trip tests for register asm labels

This commit enhances the test_register_asm_label test to include
round-trip testing, which was the main issue reported in #33.

The original issue stated: 'when I convert it back to C-Code then no
C-Code is created for this line.'

This fix adds:
- Round-trip test for basic asm syntax
- Round-trip test for __asm__ variant
- Round-trip test for different type specifiers

All tests verify that parsing and code generation work correctly.

* style: Fix ruff linting issues

- Change single quotes to double quotes in __slots__ declarations
- Fix import ordering (pycparser before pycparserext)
- Standardize quote style in test assertions

---------

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>
Co-authored-by: II Assistant <assistant@example.com>

Author: 3 people

pycparserext/ext_c_parser.py

@@ -187,6 +187,8 @@ def __iter__(self):
 # These are the same as pycparser's, but it does *not* declare __slots__--
 # so we can poke in attributes at our leisure.
 class TypeDeclExt(c_ast.TypeDecl):
+    __slots__ = ("asm", "attributes", "init")
+
     @staticmethod
     def from_pycparser(td):
         assert isinstance(td, c_ast.TypeDecl)
@@ -201,6 +203,8 @@ def from_pycparser(td):
 
 
 class ArrayDeclExt(c_ast.ArrayDecl):
+    __slots__ = ("asm", "attributes", "init")
+
     @staticmethod
     def from_pycparser(ad):
         assert isinstance(ad, c_ast.ArrayDecl)

test/test_pycparserext.py

@@ -125,6 +125,38 @@ def test_asm_label():
     assert _round_trip_matches(src)
 
 
+def test_register_asm_label():
+    from pycparser import c_ast
+
+    from pycparserext.ext_c_parser import GnuCParser, TypeDeclExt
+    src = 'register int my_var asm("my_reg");'
+    p = GnuCParser()
+    ast = p.parse(src)
+    decl = ast.ext[0]
+    assert isinstance(decl, c_ast.Decl)
+
+    # The asm attribute should be on the TypeDeclExt, not the Decl
+    assert not hasattr(decl, "asm")
+
+    # The declarator part of the Decl should be a TypeDeclExt
+    # with the asm attribute.
+    assert isinstance(decl.type, TypeDeclExt)
+    assert hasattr(decl.type, "asm")
+    assert decl.type.asm is not None
+    assert decl.type.asm.template.value == '"my_reg"'
+
+    # Test round-trip: the main issue in #33 was that no C code was generated
+    assert _round_trip_matches(src)
+
+    # Test with __asm__ variant
+    src2 = 'register int foo __asm__("bar");'
+    assert _round_trip_matches(src2)
+
+    # Test with different types
+    src3 = 'register unsigned int counter asm("r0");'
+    assert _round_trip_matches(src3)
+
+
 def test_pointer_with_attr():
     # https://github.com/inducer/pycparserext/issues/86
     src = "typedef float * __attribute__((abc)) b;"