Implement _Alignas and _Alignof support with tests (#435)

* Implement _Alignas and _Alignof support with tests

* Improve testing and avoid unnecessary alignas for typedef

* Add more tests

* Drop legacy artifact

* Remove extra _add_declaration_specifier call

* Drop custom equality comparators for now

Co-authored-by: vit9696 <vit9696@users.noreply.github.com>

4 files changed, 59 insertions, 3 deletions

diff --git a/tests/c_files/c11.c b/tests/c_files/c11.c
index 3c57f55..4f97a87 100644
--- a/tests/c_files/c11.c
+++ b/tests/c_files/c11.c
@@ -4,6 +4,7 @@
 #include <threads.h>
 #include <assert.h>
 #include <stdatomic.h>
+#include <stdalign.h>
 
 /* C11 thread locals */
 _Thread_local int flag;
@@ -12,6 +13,9 @@ _Atomic int flag3;
 _Atomic(int) flag4;
 _Atomic(_Atomic(int) *) flag5;
 atomic_bool flag6;
+_Alignas(32) int q32;
+_Alignas(long long) int qll;
+alignas(64) int qqq;
 
 static_assert(sizeof(flag) == sizeof(flag2), "Really unexpected size difference");
 
@@ -31,6 +35,8 @@ int main()
   static_assert(sizeof(flag) == sizeof(flag2), "Unexpected size difference");
   static_assert(sizeof(flag) == sizeof(flag3), "Unexpected size difference");
   static_assert(sizeof(flag) == sizeof(flag4), "Unexpected size difference");
+  static_assert(_Alignof(int) == sizeof(int), "Unexpected int alignment");
+  static_assert(alignof(int) == sizeof(int), "Unexpected int alignment");
 
   printf("Flag: %d\n", flag);
   printf("Flag2: %d\n", flag2);
diff --git a/tests/test_c_generator.py b/tests/test_c_generator.py
index fb9499a..2095e63 100644
--- a/tests/test_c_generator.py
+++ b/tests/test_c_generator.py
@@ -96,6 +96,27 @@ class TestCtoC(unittest.TestCase):
         self._assert_ctoc_correct('int test(const char* const* arg);')
         self._assert_ctoc_correct('int test(const char** const arg);')
 
+    # FIXME: These require custom equality comparison.
+    # def test_alignment(self):
+    #     self._assert_ctoc_correct('_Alignas(32) int b;')
+    #     self._assert_ctoc_correct('int _Alignas(32) a;')
+    #     self._assert_ctoc_correct('_Alignas(32) _Atomic(int) b;')
+    #     self._assert_ctoc_correct('_Atomic(int) _Alignas(32) b;')
+    #     self._assert_ctoc_correct('_Alignas(long long) int a;')
+    #     self._assert_ctoc_correct('int _Alignas(long long) a;')
+    #     self._assert_ctoc_correct(r'''
+    #         typedef struct node_t {
+    #             _Alignas(64) void* next;
+    #             int data;
+    #         } node;
+    #         ''')
+    #     self._assert_ctoc_correct(r'''
+    #         typedef struct node_t {
+    #             void _Alignas(64) * next;
+    #             int data;
+    #         } node;
+    #         ''')
+
     def test_ternary(self):
         self._assert_ctoc_correct('''
             int main(void)
diff --git a/tests/test_c_lexer.py b/tests/test_c_lexer.py
index e446434..1d3c39b 100644
--- a/tests/test_c_lexer.py
+++ b/tests/test_c_lexer.py
@@ -94,6 +94,7 @@ class TestCLexerNoErrors(unittest.TestCase):
     def test_new_keywords(self):
         self.assertTokensTypes('_Bool', ['_BOOL'])
         self.assertTokensTypes('_Atomic', ['_ATOMIC'])
+        self.assertTokensTypes('_Alignas _Alignof', ['_ALIGNAS', '_ALIGNOF'])
 
     def test_floating_constants(self):
         self.assertTokensTypes('1.5f', ['FLOAT_CONST'])
diff --git a/tests/test_c_parser.py b/tests/test_c_parser.py
index 7e6a648..5b9d916 100755
--- a/tests/test_c_parser.py
+++ b/tests/test_c_parser.py
@@ -40,16 +40,21 @@ def expand_decl(decl):
             assert isinstance(decl.values, EnumeratorList)
             values = [enum.name for enum in decl.values.enumerators]
         return ['Enum', decl.name, values]
+    elif typ == Alignas:
+        return ['Alignas', expand_init(decl.alignment)]
     elif typ == StaticAssert:
         return ['StaticAssert', decl.cond.value, decl.message.value]
     else:
         nested = expand_decl(decl.type)
 
         if typ == Decl:
+            r = ['Decl']
             if decl.quals:
-                return ['Decl', decl.quals, decl.name, nested]
-            else:
-                return ['Decl', decl.name, nested]
+                r.append(decl.quals)
+            if decl.align:
+                r.append(expand_decl(decl.align[0]))
+            r.extend([decl.name, nested])
+            return r
         elif typ == Typename: # for function parameters
             if decl.quals:
                 return ['Typename', decl.quals, nested]
@@ -98,6 +103,8 @@ def expand_init(init):
         if init.block_items:
             blocks = [expand_init(i) for i in init.block_items]
         return ['Compound', blocks]
+    elif typ == Typename:
+        return expand_decl(init)
     else:
         # Fallback to type name
         return [typ.__name__]
@@ -618,6 +625,27 @@ class TestCParser_fundamentals(TestCParser_base):
                         ['TypeDecl',
                             ['IdentifierType', ['int']]]]]])
 
+    def test_alignof(self):
+        r = self.parse('int a = _Alignof(int);')
+        self.assertEqual(expand_decl(r.ext[0]), ['Decl', 'a', ['TypeDecl', ['IdentifierType', ['int']]]])
+        self.assertEqual(expand_init(r.ext[0].init), ['UnaryOp', '_Alignof',
+            ['Typename', ['TypeDecl', ['IdentifierType', ['int']]]]])
+
+        self.assertEqual(expand_decl(self.parse('_Alignas(_Alignof(int)) char a;').ext[0]),
+            ['Decl', ['Alignas',
+                ['UnaryOp', '_Alignof', ['Typename', ['TypeDecl', ['IdentifierType', ['int']]]]]],
+                'a', ['TypeDecl', ['IdentifierType', ['char']]]])
+
+        self.assertEqual(expand_decl(self.parse('_Alignas(4) char a;').ext[0]),
+            ['Decl', ['Alignas',
+                ['Constant', 'int', '4']],
+                'a', ['TypeDecl', ['IdentifierType', ['char']]]])
+
+        self.assertEqual(expand_decl(self.parse('_Alignas(int) char a;').ext[0]),
+            ['Decl', ['Alignas',
+                ['Typename', ['TypeDecl', ['IdentifierType', ['int']]]]],
+                'a', ['TypeDecl', ['IdentifierType', ['char']]]])
+
     def test_offsetof(self):
         def expand_ref(n):
             if isinstance(n, StructRef):