C, update fundamental types, including GNU exts

Fixes sphinx-doc#9535

CHANGES

@@ -19,6 +19,7 @@ Features added
   template variable ``sphinx_version_tuple``
 * #9445: py domain: ``:py:property:`` directive supports ``:classmethod:``
   option to describe the class property
+* #9535: C, support more fundamental types, including GNU extensions.
 
 Bugs fixed
 ----------

sphinx/domains/c.py

@@ -92,6 +92,33 @@
 _string_re = re.compile(r"[LuU8]?('([^'\\]*(?:\\.[^'\\]*)*)'"
                         r'|"([^"\\]*(?:\\.[^"\\]*)*)")', re.S)
 
+_simple_type_sepcifiers_re = re.compile(r"""(?x)
+    \b(
+    void|_Bool|bool
+    # Integer
+    # -------
+    |((signed|unsigned)\s+)?(char|(
+        ((long\s+long|long)\s+)?int
+    ))
+    |__uint128|__int128
+    # extensions
+    |((signed|unsigned)\s+)?__int(8|16|32|64|128)
+    # Floating-point
+    # --------------
+    |(float|double|long\s+double)(\s+(_Complex|complex|_Imaginary|imaginary))?
+    |_Decimal(32|64|128)
+    # extensions
+    |__float80|_Float64x|__float128|_Float128|__ibm128
+    |__fp16
+    # Fixed-point, extension
+    |(_Sat\s+)?((signed|unsigned)\s+)?((short|long|long\s+long)\s+)?(_Fract|_Accum)
+    # Integer types that could be prefixes of the previous ones
+    # ---------------------------------------------------------
+    |((signed|unsigned)\s+)?(short|long\s+long|long)
+    |signed|unsigned
+    )\b
+""")
+
 
 class _DuplicateSymbolError(Exception):
     def __init__(self, symbol: "Symbol", declaration: "ASTDeclaration") -> None:
@@ -2123,15 +2150,6 @@ def dump(self, indent: int) -> str:
 
 
 class DefinitionParser(BaseParser):
-    # those without signedness and size modifiers
-    # see https://en.cppreference.com/w/cpp/language/types
-    _simple_fundamental_types = (
-        'void', '_Bool', 'bool', 'char', 'int', 'float', 'double',
-        '__int64',
-    )
-
-    _prefix_keys = ('struct', 'enum', 'union')
-
     @property
     def language(self) -> str:
         return 'C'
@@ -2556,40 +2574,16 @@ def _parse_nested_name(self) -> ASTNestedName:
         return ASTNestedName(names, rooted)
 
     def _parse_trailing_type_spec(self) -> ASTTrailingTypeSpec:
-        # fundamental types
+        # fundamental types, https://en.cppreference.com/w/c/language/type
+        # and extensions
         self.skip_ws()
-        for t in self._simple_fundamental_types:
-            if self.skip_word(t):
-                return ASTTrailingTypeSpecFundamental(t)
-
-        # TODO: this could/should be more strict
-        elements = []
-        if self.skip_word_and_ws('signed'):
-            elements.append('signed')
-        elif self.skip_word_and_ws('unsigned'):
-            elements.append('unsigned')
-        while 1:
-            if self.skip_word_and_ws('short'):
-                elements.append('short')
-            elif self.skip_word_and_ws('long'):
-                elements.append('long')
-            else:
-                break
-        if self.skip_word_and_ws('char'):
-            elements.append('char')
-        elif self.skip_word_and_ws('int'):
-            elements.append('int')
-        elif self.skip_word_and_ws('double'):
-            elements.append('double')
-        elif self.skip_word_and_ws('__int64'):
-            elements.append('__int64')
-        if len(elements) > 0:
-            return ASTTrailingTypeSpecFundamental(' '.join(elements))
+        if self.match(_simple_type_sepcifiers_re):
+            return ASTTrailingTypeSpecFundamental(self.matched_text)
 
         # prefixed
         prefix = None
         self.skip_ws()
-        for k in self._prefix_keys:
+        for k in ('struct', 'enum', 'union'):
             if self.skip_word_and_ws(k):
                 prefix = k
                 break

tests/test_domain_c.py

@@ -275,6 +275,58 @@ def exprCheck(expr, output=None):
     exprCheck('a or_eq 5')
 
 
+def test_domain_c_ast_fundamental_types():
+    def types():
+        def signed(t):
+            yield t
+            yield 'signed ' + t
+            yield 'unsigned ' + t
+
+        # integer types
+        # -------------
+        yield 'void'
+        yield from ('_Bool', 'bool')
+        yield from signed('char')
+        yield from signed('short')
+        yield from signed('int')
+        yield from ('signed', 'unsigned')
+        yield from signed('long')
+        yield from signed('long int')
+        yield from signed('long long')
+        yield from signed('long long int')
+        yield from ('__int128', '__uint128')
+        # extensions
+        for t in ('__int8', '__int16', '__int32', '__int64', '__int128'):
+            yield from signed(t)
+
+        # floating point types
+        # --------------------
+        yield from ('_Decimal32', '_Decimal64', '_Decimal128')
+        for f in ('float', 'double', 'long double'):
+            yield f
+            yield from (f + " _Complex", f + " complex")
+            yield from (f + " _Imaginary", f + " imaginary")
+        # extensions
+        # https://gcc.gnu.org/onlinedocs/gcc/Floating-Types.html#Floating-Types
+        yield from ('__float80', '_Float64x',
+                    '__float128', '_Float128',
+                    '__ibm128')
+        # https://gcc.gnu.org/onlinedocs/gcc/Half-Precision.html#Half-Precision
+        yield '__fp16'
+
+        # fixed-point types (extension)
+        # -----------------------------
+        # https://gcc.gnu.org/onlinedocs/gcc/Fixed-Point.html#Fixed-Point
+        for sat in ('', '_Sat '):
+            for t in ('_Fract', '_Accum'):
+                for size in ('short ', '', 'long ', 'long long '):
+                    for tt in signed(size + t):
+                        yield sat + tt
+
+    for t in types():
+        check('type', "{key}%s foo" % t, {1: 'foo'}, key='typedef')
+
+
 def test_domain_c_ast_type_definitions():
     check('type', "{key}T", {1: "T"})