Refactor C and C++ AST types (#12312)

- Define ``__eq__`` and ``__hash__`` methods for AST types
- Improve the base ``__eq__`` method
- Cache the value of ``is_anon()``
- Rename ``ASTIdentifier.identifier``
- Various other serialisation improvements

sphinx/domains/c/_ast.py

@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+import sys
+import warnings
 from typing import TYPE_CHECKING, Any, Union, cast
 
 from docutils import nodes
@@ -38,39 +40,40 @@ class ASTBase(ASTBaseBase):
 ################################################################################
 
 class ASTIdentifier(ASTBaseBase):
-    def __init__(self, identifier: str) -> None:
+    def __init__(self, name: str) -> None:
-        assert identifier is not None
+        if not isinstance(name, str) or len(name) == 0:
-        assert len(identifier) != 0
+            raise AssertionError
-        self.identifier = identifier
+        self.name = sys.intern(name)
+        self.is_anonymous = name[0] == '@'
 
     # ASTBaseBase already implements this method,
     # but specialising it here improves performance
     def __eq__(self, other: object) -> bool:
-        if type(other) is not ASTIdentifier:
+        if not isinstance(other, ASTIdentifier):
             return NotImplemented
-        return self.identifier == other.identifier
+        return self.name == other.name
 
     def is_anon(self) -> bool:
-        return self.identifier[0] == '@'
+        return self.is_anonymous
 
     # and this is where we finally make a difference between __str__ and the display string
 
     def __str__(self) -> str:
-        return self.identifier
+        return self.name
 
     def get_display_string(self) -> str:
-        return "[anonymous]" if self.is_anon() else self.identifier
+        return "[anonymous]" if self.is_anonymous else self.name
 
     def describe_signature(self, signode: TextElement, mode: str, env: BuildEnvironment,
                            prefix: str, symbol: Symbol) -> None:
         # note: slightly different signature of describe_signature due to the prefix
         verify_description_mode(mode)
-        if self.is_anon():
+        if self.is_anonymous:
             node = addnodes.desc_sig_name(text="[anonymous]")
         else:
-            node = addnodes.desc_sig_name(self.identifier, self.identifier)
+            node = addnodes.desc_sig_name(self.name, self.name)
         if mode == 'markType':
-            targetText = prefix + self.identifier
+            targetText = prefix + self.name
             pnode = addnodes.pending_xref('', refdomain='c',
                                           reftype='identifier',
                                           reftarget=targetText, modname=None,
@@ -87,6 +90,14 @@ class ASTIdentifier(ASTBaseBase):
         else:
             raise Exception('Unknown description mode: %s' % mode)
 
+    @property
+    def identifier(self) -> str:
+        warnings.warn(
+            '`ASTIdentifier.identifier` is deprecated, use `ASTIdentifier.name` instead',
+            DeprecationWarning, stacklevel=2,
+        )
+        return self.name
+
 
 class ASTNestedName(ASTBase):
     def __init__(self, names: list[ASTIdentifier], rooted: bool) -> None:
@@ -94,6 +105,14 @@ class ASTNestedName(ASTBase):
         self.names = names
         self.rooted = rooted
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTNestedName):
+            return NotImplemented
+        return self.names == other.names and self.rooted == other.rooted
+
+    def __hash__(self) -> int:
+        return hash((self.names, self.rooted))
+
     @property
     def name(self) -> ASTNestedName:
         return self
@@ -186,6 +205,14 @@ class ASTBooleanLiteral(ASTLiteral):
     def __init__(self, value: bool) -> None:
         self.value = value
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTBooleanLiteral):
+            return NotImplemented
+        return self.value == other.value
+
+    def __hash__(self) -> int:
+        return hash(self.value)
+
     def _stringify(self, transform: StringifyTransform) -> str:
         if self.value:
             return 'true'
@@ -202,6 +229,14 @@ class ASTNumberLiteral(ASTLiteral):
     def __init__(self, data: str) -> None:
         self.data = data
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTNumberLiteral):
+            return NotImplemented
+        return self.data == other.data
+
+    def __hash__(self) -> int:
+        return hash(self.data)
+
     def _stringify(self, transform: StringifyTransform) -> str:
         return self.data
 
@@ -221,6 +256,17 @@ class ASTCharLiteral(ASTLiteral):
         else:
             raise UnsupportedMultiCharacterCharLiteral(decoded)
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTCharLiteral):
+            return NotImplemented
+        return (
+            self.prefix == other.prefix
+            and self.value == other.value
+        )
+
+    def __hash__(self) -> int:
+        return hash((self.prefix, self.value))
+
     def _stringify(self, transform: StringifyTransform) -> str:
         if self.prefix is None:
             return "'" + self.data + "'"
@@ -237,6 +283,14 @@ class ASTStringLiteral(ASTLiteral):
     def __init__(self, data: str) -> None:
         self.data = data
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTStringLiteral):
+            return NotImplemented
+        return self.data == other.data
+
+    def __hash__(self) -> int:
+        return hash(self.data)
+
     def _stringify(self, transform: StringifyTransform) -> str:
         return self.data
 
@@ -251,6 +305,14 @@ class ASTIdExpression(ASTExpression):
         # note: this class is basically to cast a nested name as an expression
         self.name = name
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTIdExpression):
+            return NotImplemented
+        return self.name == other.name
+
+    def __hash__(self) -> int:
+        return hash(self.name)
+
     def _stringify(self, transform: StringifyTransform) -> str:
         return transform(self.name)
 
@@ -266,6 +328,14 @@ class ASTParenExpr(ASTExpression):
     def __init__(self, expr: ASTExpression) -> None:
         self.expr = expr
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTParenExpr):
+            return NotImplemented
+        return self.expr == other.expr
+
+    def __hash__(self) -> int:
+        return hash(self.expr)
+
     def _stringify(self, transform: StringifyTransform) -> str:
         return '(' + transform(self.expr) + ')'
 
@@ -290,6 +360,14 @@ class ASTPostfixCallExpr(ASTPostfixOp):
     def __init__(self, lst: ASTParenExprList | ASTBracedInitList) -> None:
         self.lst = lst
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTPostfixCallExpr):
+            return NotImplemented
+        return self.lst == other.lst
+
+    def __hash__(self) -> int:
+        return hash(self.lst)
+
     def _stringify(self, transform: StringifyTransform) -> str:
         return transform(self.lst)
 
@@ -302,6 +380,14 @@ class ASTPostfixArray(ASTPostfixOp):
     def __init__(self, expr: ASTExpression) -> None:
         self.expr = expr
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTPostfixArray):
+            return NotImplemented
+        return self.expr == other.expr
+
+    def __hash__(self) -> int:
+        return hash(self.expr)
+
     def _stringify(self, transform: StringifyTransform) -> str:
         return '[' + transform(self.expr) + ']'
 
@@ -334,6 +420,14 @@ class ASTPostfixMemberOfPointer(ASTPostfixOp):
     def __init__(self, name: ASTNestedName) -> None:
         self.name = name
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTPostfixMemberOfPointer):
+            return NotImplemented
+        return self.name == other.name
+
+    def __hash__(self) -> int:
+        return hash(self.name)
+
     def _stringify(self, transform: StringifyTransform) -> str:
         return '->' + transform(self.name)
 
@@ -348,6 +442,14 @@ class ASTPostfixExpr(ASTExpression):
         self.prefix = prefix
         self.postFixes = postFixes
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTPostfixExpr):
+            return NotImplemented
+        return self.prefix == other.prefix and self.postFixes == other.postFixes
+
+    def __hash__(self) -> int:
+        return hash((self.prefix, self.postFixes))
+
     def _stringify(self, transform: StringifyTransform) -> str:
         return ''.join([transform(self.prefix), *(transform(p) for p in self.postFixes)])
 
@@ -366,6 +468,14 @@ class ASTUnaryOpExpr(ASTExpression):
         self.op = op
         self.expr = expr
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTUnaryOpExpr):
+            return NotImplemented
+        return self.op == other.op and self.expr == other.expr
+
+    def __hash__(self) -> int:
+        return hash((self.op, self.expr))
+
     def _stringify(self, transform: StringifyTransform) -> str:
         if self.op[0] in 'cn':
             return self.op + " " + transform(self.expr)
@@ -386,6 +496,14 @@ class ASTSizeofType(ASTExpression):
     def __init__(self, typ: ASTType) -> None:
         self.typ = typ
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTSizeofType):
+            return NotImplemented
+        return self.typ == other.typ
+
+    def __hash__(self) -> int:
+        return hash(self.typ)
+
     def _stringify(self, transform: StringifyTransform) -> str:
         return "sizeof(" + transform(self.typ) + ")"
 
@@ -401,6 +519,14 @@ class ASTSizeofExpr(ASTExpression):
     def __init__(self, expr: ASTExpression) -> None:
         self.expr = expr
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTSizeofExpr):
+            return NotImplemented
+        return self.expr == other.expr
+
+    def __hash__(self) -> int:
+        return hash(self.expr)
+
     def _stringify(self, transform: StringifyTransform) -> str:
         return "sizeof " + transform(self.expr)
 
@@ -415,6 +541,14 @@ class ASTAlignofExpr(ASTExpression):
     def __init__(self, typ: ASTType) -> None:
         self.typ = typ
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTAlignofExpr):
+            return NotImplemented
+        return self.typ == other.typ
+
+    def __hash__(self) -> int:
+        return hash(self.typ)
+
     def _stringify(self, transform: StringifyTransform) -> str:
         return "alignof(" + transform(self.typ) + ")"
 
@@ -434,6 +568,17 @@ class ASTCastExpr(ASTExpression):
         self.typ = typ
         self.expr = expr
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTCastExpr):
+            return NotImplemented
+        return (
+            self.typ == other.typ
+            and self.expr == other.expr
+        )
+
+    def __hash__(self) -> int:
+        return hash((self.typ, self.expr))
+
     def _stringify(self, transform: StringifyTransform) -> str:
         res = ['(']
         res.append(transform(self.typ))
@@ -456,6 +601,17 @@ class ASTBinOpExpr(ASTBase):
         self.exprs = exprs
         self.ops = ops
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTBinOpExpr):
+            return NotImplemented
+        return (
+            self.exprs == other.exprs
+            and self.ops == other.ops
+        )
+
+    def __hash__(self) -> int:
+        return hash((self.exprs, self.ops))
+
     def _stringify(self, transform: StringifyTransform) -> str:
         res = []
         res.append(transform(self.exprs[0]))
@@ -487,6 +643,17 @@ class ASTAssignmentExpr(ASTExpression):
         self.exprs = exprs
         self.ops = ops
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTAssignmentExpr):
+            return NotImplemented
+        return (
+            self.exprs == other.exprs
+            and self.ops == other.ops
+        )
+
+    def __hash__(self) -> int:
+        return hash((self.exprs, self.ops))
+
     def _stringify(self, transform: StringifyTransform) -> str:
         res = []
         res.append(transform(self.exprs[0]))
@@ -515,6 +682,14 @@ class ASTFallbackExpr(ASTExpression):
     def __init__(self, expr: str) -> None:
         self.expr = expr
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTFallbackExpr):
+            return NotImplemented
+        return self.expr == other.expr
+
+    def __hash__(self) -> int:
+        return hash(self.expr)
+
     def _stringify(self, transform: StringifyTransform) -> str:
         return self.expr
 
@@ -539,6 +714,14 @@ class ASTTrailingTypeSpecFundamental(ASTTrailingTypeSpec):
         assert len(names) != 0
         self.names = names
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTTrailingTypeSpecFundamental):
+            return NotImplemented
+        return self.names == other.names
+
+    def __hash__(self) -> int:
+        return hash(self.names)
+
     def _stringify(self, transform: StringifyTransform) -> str:
         return ' '.join(self.names)
 
@@ -558,6 +741,17 @@ class ASTTrailingTypeSpecName(ASTTrailingTypeSpec):
         self.prefix = prefix
         self.nestedName = nestedName
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTTrailingTypeSpecName):
+            return NotImplemented
+        return (
+            self.prefix == other.prefix
+            and self.nestedName == other.nestedName
+        )
+
+    def __hash__(self) -> int:
+        return hash((self.prefix, self.nestedName))
+
     @property
     def name(self) -> ASTNestedName:
         return self.nestedName
@@ -583,6 +777,14 @@ class ASTFunctionParameter(ASTBase):
         self.arg = arg
         self.ellipsis = ellipsis
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTFunctionParameter):
+            return NotImplemented
+        return self.arg == other.arg and self.ellipsis == other.ellipsis
+
+    def __hash__(self) -> int:
+        return hash((self.arg, self.ellipsis))
+
     def get_id(self, version: int, objectType: str, symbol: Symbol) -> str:
         # the anchor will be our parent
         return symbol.parent.declaration.get_id(version, prefixed=False)
@@ -607,6 +809,14 @@ class ASTParameters(ASTBase):
         self.args = args
         self.attrs = attrs
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTParameters):
+            return NotImplemented
+        return self.args == other.args and self.attrs == other.attrs
+
+    def __hash__(self) -> int:
+        return hash((self.args, self.attrs))
+
     @property
     def function_params(self) -> list[ASTFunctionParameter]:
         return self.args
@@ -674,6 +884,30 @@ class ASTDeclSpecsSimple(ASTBaseBase):
         self.const = const
         self.attrs = attrs
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTDeclSpecsSimple):
+            return NotImplemented
+        return (
+            self.storage == other.storage
+            and self.threadLocal == other.threadLocal
+            and self.inline == other.inline
+            and self.restrict == other.restrict
+            and self.volatile == other.volatile
+            and self.const == other.const
+            and self.attrs == other.attrs
+        )
+
+    def __hash__(self) -> int:
+        return hash((
+            self.storage,
+            self.threadLocal,
+            self.inline,
+            self.restrict,
+            self.volatile,
+            self.const,
+            self.attrs,
+        ))
+
     def mergeWith(self, other: ASTDeclSpecsSimple) -> ASTDeclSpecsSimple:
         if not other:
             return self
@@ -741,6 +975,24 @@ class ASTDeclSpecs(ASTBase):
         self.allSpecs = self.leftSpecs.mergeWith(self.rightSpecs)
         self.trailingTypeSpec = trailing
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTDeclSpecs):
+            return NotImplemented
+        return (
+            self.outer == other.outer
+            and self.leftSpecs == other.leftSpecs
+            and self.rightSpecs == other.rightSpecs
+            and self.trailingTypeSpec == other.trailingTypeSpec
+        )
+
+    def __hash__(self) -> int:
+        return hash((
+            self.outer,
+            self.leftSpecs,
+            self.rightSpecs,
+            self.trailingTypeSpec,
+        ))
+
     def _stringify(self, transform: StringifyTransform) -> str:
         res: list[str] = []
         l = transform(self.leftSpecs)
@@ -796,6 +1048,28 @@ class ASTArray(ASTBase):
         if size is not None:
             assert not vla
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTArray):
+            return NotImplemented
+        return (
+            self.static == other.static
+            and self.const == other.const
+            and self.volatile == other.volatile
+            and self.restrict == other.restrict
+            and self.vla == other.vla
+            and self.size == other.size
+        )
+
+    def __hash__(self) -> int:
+        return hash((
+            self.static,
+            self.const,
+            self.volatile,
+            self.restrict,
+            self.vla,
+            self.size,
+        ))
+
     def _stringify(self, transform: StringifyTransform) -> str:
         el = []
         if self.static:
@@ -861,6 +1135,18 @@ class ASTDeclaratorNameParam(ASTDeclarator):
         self.arrayOps = arrayOps
         self.param = param
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTDeclaratorNameParam):
+            return NotImplemented
+        return (
+            self.declId == other.declId
+            and self.arrayOps == other.arrayOps
+            and self.param == other.param
+        )
+
+    def __hash__(self) -> int:
+        return hash((self.declId, self.arrayOps, self.param))
+
     @property
     def name(self) -> ASTNestedName:
         return self.declId
@@ -899,6 +1185,14 @@ class ASTDeclaratorNameBitField(ASTDeclarator):
         self.declId = declId
         self.size = size
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTDeclaratorNameBitField):
+            return NotImplemented
+        return self.declId == other.declId and self.size == other.size
+
+    def __hash__(self) -> int:
+        return hash((self.declId, self.size))
+
     @property
     def name(self) -> ASTNestedName:
         return self.declId
@@ -937,6 +1231,20 @@ class ASTDeclaratorPtr(ASTDeclarator):
         self.const = const
         self.attrs = attrs
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTDeclaratorPtr):
+            return NotImplemented
+        return (
+            self.next == other.next
+            and self.restrict == other.restrict
+            and self.volatile == other.volatile
+            and self.const == other.const
+            and self.attrs == other.attrs
+        )
+
+    def __hash__(self) -> int:
+        return hash((self.next, self.restrict, self.volatile, self.const, self.attrs))
+
     @property
     def name(self) -> ASTNestedName:
         return self.next.name
@@ -1006,6 +1314,14 @@ class ASTDeclaratorParen(ASTDeclarator):
         self.next = next
         # TODO: we assume the name and params are in inner
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTDeclaratorParen):
+            return NotImplemented
+        return self.inner == other.inner and self.next == other.next
+
+    def __hash__(self) -> int:
+        return hash((self.inner, self.next))
+
     @property
     def name(self) -> ASTNestedName:
         return self.inner.name
@@ -1040,6 +1356,14 @@ class ASTParenExprList(ASTBaseParenExprList):
     def __init__(self, exprs: list[ASTExpression]) -> None:
         self.exprs = exprs
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTParenExprList):
+            return NotImplemented
+        return self.exprs == other.exprs
+
+    def __hash__(self) -> int:
+        return hash(self.exprs)
+
     def _stringify(self, transform: StringifyTransform) -> str:
         exprs = [transform(e) for e in self.exprs]
         return '(%s)' % ', '.join(exprs)
@@ -1064,6 +1388,14 @@ class ASTBracedInitList(ASTBase):
         self.exprs = exprs
         self.trailingComma = trailingComma
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTBracedInitList):
+            return NotImplemented
+        return self.exprs == other.exprs and self.trailingComma == other.trailingComma
+
+    def __hash__(self) -> int:
+        return hash((self.exprs, self.trailingComma))
+
     def _stringify(self, transform: StringifyTransform) -> str:
         exprs = ', '.join(transform(e) for e in self.exprs)
         trailingComma = ',' if self.trailingComma else ''
@@ -1092,6 +1424,14 @@ class ASTInitializer(ASTBase):
         self.value = value
         self.hasAssign = hasAssign
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTInitializer):
+            return NotImplemented
+        return self.value == other.value and self.hasAssign == other.hasAssign
+
+    def __hash__(self) -> int:
+        return hash((self.value, self.hasAssign))
+
     def _stringify(self, transform: StringifyTransform) -> str:
         val = transform(self.value)
         if self.hasAssign:
@@ -1116,6 +1456,14 @@ class ASTType(ASTBase):
         self.declSpecs = declSpecs
         self.decl = decl
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTType):
+            return NotImplemented
+        return self.declSpecs == other.declSpecs and self.decl == other.decl
+
+    def __hash__(self) -> int:
+        return hash((self.declSpecs, self.decl))
+
     @property
     def name(self) -> ASTNestedName:
         return self.decl.name
@@ -1161,6 +1509,14 @@ class ASTTypeWithInit(ASTBase):
         self.type = type
         self.init = init
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTTypeWithInit):
+            return NotImplemented
+        return self.type == other.type and self.init == other.init
+
+    def __hash__(self) -> int:
+        return hash((self.type, self.init))
+
     @property
     def name(self) -> ASTNestedName:
         return self.type.name
@@ -1190,6 +1546,18 @@ class ASTMacroParameter(ASTBase):
         self.ellipsis = ellipsis
         self.variadic = variadic
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTMacroParameter):
+            return NotImplemented
+        return (
+            self.arg == other.arg
+            and self.ellipsis == other.ellipsis
+            and self.variadic == other.variadic
+        )
+
+    def __hash__(self) -> int:
+        return hash((self.arg, self.ellipsis, self.variadic))
+
     def _stringify(self, transform: StringifyTransform) -> str:
         if self.ellipsis:
             return '...'
@@ -1215,6 +1583,14 @@ class ASTMacro(ASTBase):
         self.ident = ident
         self.args = args
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTMacro):
+            return NotImplemented
+        return self.ident == other.ident and self.args == other.args
+
+    def __hash__(self) -> int:
+        return hash((self.ident, self.args))
+
     @property
     def name(self) -> ASTNestedName:
         return self.ident
@@ -1254,6 +1630,14 @@ class ASTStruct(ASTBase):
     def __init__(self, name: ASTNestedName) -> None:
         self.name = name
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTStruct):
+            return NotImplemented
+        return self.name == other.name
+
+    def __hash__(self) -> int:
+        return hash(self.name)
+
     def get_id(self, version: int, objectType: str, symbol: Symbol) -> str:
         return symbol.get_full_nested_name().get_id(version)
 
@@ -1270,6 +1654,14 @@ class ASTUnion(ASTBase):
     def __init__(self, name: ASTNestedName) -> None:
         self.name = name
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTUnion):
+            return NotImplemented
+        return self.name == other.name
+
+    def __hash__(self) -> int:
+        return hash(self.name)
+
     def get_id(self, version: int, objectType: str, symbol: Symbol) -> str:
         return symbol.get_full_nested_name().get_id(version)
 
@@ -1286,6 +1678,14 @@ class ASTEnum(ASTBase):
     def __init__(self, name: ASTNestedName) -> None:
         self.name = name
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTEnum):
+            return NotImplemented
+        return self.name == other.name
+
+    def __hash__(self) -> int:
+        return hash(self.name)
+
     def get_id(self, version: int, objectType: str, symbol: Symbol) -> str:
         return symbol.get_full_nested_name().get_id(version)
 
@@ -1305,6 +1705,18 @@ class ASTEnumerator(ASTBase):
         self.init = init
         self.attrs = attrs
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTEnumerator):
+            return NotImplemented
+        return (
+            self.name == other.name
+            and self.init == other.init
+            and self.attrs == other.attrs
+        )
+
+    def __hash__(self) -> int:
+        return hash((self.name, self.init, self.attrs))
+
     def get_id(self, version: int, objectType: str, symbol: Symbol) -> str:
         return symbol.get_full_nested_name().get_id(version)
 
@@ -1346,6 +1758,18 @@ class ASTDeclaration(ASTBaseBase):
         # further changes will be made to this object
         self._newest_id_cache: str | None = None
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTDeclaration):
+            return NotImplemented
+        return (
+            self.objectType == other.objectType
+            and self.directiveType == other.directiveType
+            and self.declaration == other.declaration
+            and self.semicolon == other.semicolon
+            and self.symbol == other.symbol
+            and self.enumeratorScopedSymbol == other.enumeratorScopedSymbol
+        )
+
     def clone(self) -> ASTDeclaration:
         return ASTDeclaration(self.objectType, self.directiveType,
                               self.declaration.clone(), self.semicolon)

sphinx/domains/c/_symbol.py

@@ -114,6 +114,9 @@ class Symbol:
         # Do symbol addition after self._children has been initialised.
         self._add_function_params()
 
+    def __repr__(self) -> str:
+        return f'<Symbol {self.to_string(indent=0)!r}>'
+
     def _fill_empty(self, declaration: ASTDeclaration, docname: str, line: int) -> None:
         self._assert_invariants()
         assert self.declaration is None

sphinx/domains/cpp/_symbol.py

@@ -155,6 +155,9 @@ class Symbol:
         # Do symbol addition after self._children has been initialised.
         self._add_template_and_function_params()
 
+    def __repr__(self) -> str:
+        return f'<Symbol {self.to_string(indent=0)!r}>'
+
     def _fill_empty(self, declaration: ASTDeclaration, docname: str, line: int) -> None:
         self._assert_invariants()
         assert self.declaration is None

sphinx/util/cfamily.py

@@ -90,17 +90,11 @@ class NoOldIdError(Exception):
 class ASTBaseBase:
     def __eq__(self, other: object) -> bool:
         if type(self) is not type(other):
-            return False
+            return NotImplemented
         try:
-            for key, value in self.__dict__.items():
+            return self.__dict__ == other.__dict__
-                if value != getattr(other, key):
-                    return False
         except AttributeError:
             return False
-        return True
-
-    # Defining __hash__ = None is not strictly needed when __eq__ is defined.
-    __hash__ = None  # type: ignore[assignment]
 
     def clone(self) -> Any:
         return deepcopy(self)
@@ -115,7 +109,7 @@ class ASTBaseBase:
         return self._stringify(lambda ast: ast.get_display_string())
 
     def __repr__(self) -> str:
-        return '<%s>' % self.__class__.__name__
+        return f'<{self.__class__.__name__}: {self._stringify(repr)}>'
 
 
 ################################################################################
@@ -131,8 +125,16 @@ class ASTCPPAttribute(ASTAttribute):
     def __init__(self, arg: str) -> None:
         self.arg = arg
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTCPPAttribute):
+            return NotImplemented
+        return self.arg == other.arg
+
+    def __hash__(self) -> int:
+        return hash(self.arg)
+
     def _stringify(self, transform: StringifyTransform) -> str:
-        return "[[" + self.arg + "]]"
+        return f"[[{self.arg}]]"
 
     def describe_signature(self, signode: TextElement) -> None:
         signode.append(addnodes.desc_sig_punctuation('[[', '[['))
@@ -146,35 +148,37 @@ class ASTGnuAttribute(ASTBaseBase):
         self.args = args
 
     def __eq__(self, other: object) -> bool:
-        if type(other) is not ASTGnuAttribute:
+        if not isinstance(other, ASTGnuAttribute):
             return NotImplemented
         return self.name == other.name and self.args == other.args
 
+    def __hash__(self) -> int:
+        return hash((self.name, self.args))
+
     def _stringify(self, transform: StringifyTransform) -> str:
-        res = [self.name]
         if self.args:
-            res.append(transform(self.args))
+            return self.name + transform(self.args)
-        return ''.join(res)
+        return self.name
 
 
 class ASTGnuAttributeList(ASTAttribute):
     def __init__(self, attrs: list[ASTGnuAttribute]) -> None:
         self.attrs = attrs
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTGnuAttributeList):
+            return NotImplemented
+        return self.attrs == other.attrs
+
+    def __hash__(self) -> int:
+        return hash(self.attrs)
+
     def _stringify(self, transform: StringifyTransform) -> str:
-        res = ['__attribute__((']
+        attrs = ', '.join(map(transform, self.attrs))
-        first = True
+        return f'__attribute__(({attrs}))'
-        for attr in self.attrs:
-            if not first:
-                res.append(', ')
-            first = False
-            res.append(transform(attr))
-        res.append('))')
-        return ''.join(res)
 
     def describe_signature(self, signode: TextElement) -> None:
-        txt = str(self)
+        signode.append(nodes.Text(str(self)))
-        signode.append(nodes.Text(txt))
 
 
 class ASTIdAttribute(ASTAttribute):
@@ -183,6 +187,14 @@ class ASTIdAttribute(ASTAttribute):
     def __init__(self, id: str) -> None:
         self.id = id
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTIdAttribute):
+            return NotImplemented
+        return self.id == other.id
+
+    def __hash__(self) -> int:
+        return hash(self.id)
+
     def _stringify(self, transform: StringifyTransform) -> str:
         return self.id
 
@@ -197,12 +209,19 @@ class ASTParenAttribute(ASTAttribute):
         self.id = id
         self.arg = arg
 
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ASTParenAttribute):
+            return NotImplemented
+        return self.id == other.id and self.arg == other.arg
+
+    def __hash__(self) -> int:
+        return hash((self.id, self.arg))
+
     def _stringify(self, transform: StringifyTransform) -> str:
-        return self.id + '(' + self.arg + ')'
+        return f'{self.id}({self.arg})'
 
     def describe_signature(self, signode: TextElement) -> None:
-        txt = str(self)
+        signode.append(nodes.Text(str(self)))
-        signode.append(nodes.Text(txt))
 
 
 class ASTAttributeList(ASTBaseBase):
@@ -210,10 +229,13 @@ class ASTAttributeList(ASTBaseBase):
         self.attrs = attrs
 
     def __eq__(self, other: object) -> bool:
-        if type(other) is not ASTAttributeList:
+        if not isinstance(other, ASTAttributeList):
             return NotImplemented
         return self.attrs == other.attrs
 
+    def __hash__(self) -> int:
+        return hash(self.attrs)
+
     def __len__(self) -> int:
         return len(self.attrs)
 
@@ -221,7 +243,7 @@ class ASTAttributeList(ASTBaseBase):
         return ASTAttributeList(self.attrs + other.attrs)
 
     def _stringify(self, transform: StringifyTransform) -> str:
-        return ' '.join(transform(attr) for attr in self.attrs)
+        return ' '.join(map(transform, self.attrs))
 
     def describe_signature(self, signode: TextElement) -> None:
         if len(self.attrs) == 0: