[C++] Ensure consistent non-specialization template argument representation

Previously, in certain cases the template arguments of
non-specializations were retained, leading to incorrect merging of symbols.

sphinx/domains/cpp.py

@@ -2604,6 +2604,10 @@ class ASTDeclaratorPtr(ASTDeclarator):
     def name(self, name: ASTNestedName) -> None:
         self.next.name = name
 
+    @property
+    def isPack(self) -> bool:
+        return self.next.isPack
+
     @property
     def function_params(self) -> List[ASTFunctionParameter]:
         return self.next.function_params
@@ -2707,7 +2711,7 @@ class ASTDeclaratorRef(ASTDeclarator):
 
     @property
     def isPack(self) -> bool:
-        return True
+        return self.next.isPack
 
     @property
     def function_params(self) -> List[ASTFunctionParameter]:
@@ -2779,6 +2783,10 @@ class ASTDeclaratorParamPack(ASTDeclarator):
     def trailingReturn(self) -> "ASTType":
         return self.next.trailingReturn
 
+    @property
+    def isPack(self) -> bool:
+        return True
+
     def require_space_after_declSpecs(self) -> bool:
         return False
 
@@ -2835,6 +2843,10 @@ class ASTDeclaratorMemPtr(ASTDeclarator):
     def name(self, name: ASTNestedName) -> None:
         self.next.name = name
 
+    @property
+    def isPack(self):
+        return self.next.isPack
+
     @property
     def function_params(self) -> List[ASTFunctionParameter]:
         return self.next.function_params
@@ -2932,6 +2944,10 @@ class ASTDeclaratorParen(ASTDeclarator):
     def name(self, name: ASTNestedName) -> None:
         self.inner.name = name
 
+    @property
+    def isPack(self):
+        return self.inner.isPack or self.next.isPack
+
     @property
     def function_params(self) -> List[ASTFunctionParameter]:
         return self.inner.function_params
@@ -3510,6 +3526,14 @@ class ASTTemplateParam(ASTBase):
                            env: "BuildEnvironment", symbol: "Symbol") -> None:
         raise NotImplementedError(repr(self))
 
+    @property
+    def isPack(self) -> bool:
+        raise NotImplementedError(repr(self))
+
+    @property
+    def name(self) -> ASTNestedName:
+        raise NotImplementedError(repr(self))
+
 
 class ASTTemplateKeyParamPackIdDefault(ASTTemplateParam):
     def __init__(self, key: str, identifier: ASTIdentifier,
@@ -4129,6 +4153,31 @@ class LookupKey:
         self.data = data
 
 
+def _is_specialization(templateParams: Union[ASTTemplateParams, ASTTemplateIntroduction],
+                       templateArgs: ASTTemplateArgs) -> bool:
+    """Checks if `templateArgs` does not exactly match `templateParams`."""
+    # the names of the template parameters must be given exactly as args
+    # and params that are packs must in the args be the name expanded
+    if len(templateParams.params) != len(templateArgs.args):
+        return True
+    # having no template params and no arguments is also a specialization
+    if len(templateParams.params) == 0:
+        return True
+    for i in range(len(templateParams.params)):
+        param = templateParams.params[i]
+        arg = templateArgs.args[i]
+        # TODO: doing this by string manipulation is probably not the most efficient
+        paramName = str(param.name)
+        argTxt = str(arg)
+        isArgPackExpansion = argTxt.endswith('...')
+        if param.isPack != isArgPackExpansion:
+            return True
+        argName = argTxt[:-3] if isArgPackExpansion else argTxt
+        if paramName != argName:
+            return True
+    return False
+
+
 class Symbol:
     debug_indent = 0
     debug_indent_string = "  "
@@ -4177,6 +4226,16 @@ class Symbol:
         self.siblingAbove: Symbol = None
         self.siblingBelow: Symbol = None
         self.identOrOp = identOrOp
+        # Ensure the same symbol for `A` is created for:
+        #
+        #     .. cpp:class:: template <typename T> class A
+        #
+        # and
+        #
+        #     .. cpp:function:: template <typename T> int A<T>::foo()
+        if (templateArgs is not None and
+                not _is_specialization(templateParams, templateArgs)):
+            templateArgs = None
         self.templateParams = templateParams  # template<templateParams>
         self.templateArgs = templateArgs  # identifier<templateArgs>
         self.declaration = declaration
@@ -4357,33 +4416,12 @@ class Symbol:
             Symbol.debug_print("correctPrimaryTemplateAargs:", correctPrimaryTemplateArgs)
             Symbol.debug_print("searchInSiblings:           ", searchInSiblings)
 
-        def isSpecialization() -> bool:
-            # the names of the template parameters must be given exactly as args
-            # and params that are packs must in the args be the name expanded
-            if len(templateParams.params) != len(templateArgs.args):
-                return True
-            # having no template params and no arguments is also a specialization
-            if len(templateParams.params) == 0:
-                return True
-            for i in range(len(templateParams.params)):
-                param = templateParams.params[i]
-                arg = templateArgs.args[i]
-                # TODO: doing this by string manipulation is probably not the most efficient
-                paramName = str(param.name)
-                argTxt = str(arg)
-                isArgPackExpansion = argTxt.endswith('...')
-                if param.isPack != isArgPackExpansion:
-                    return True
-                argName = argTxt[:-3] if isArgPackExpansion else argTxt
-                if paramName != argName:
-                    return True
-            return False
         if correctPrimaryTemplateArgs:
             if templateParams is not None and templateArgs is not None:
                 # If both are given, but it's not a specialization, then do lookup as if
                 # there is no argument list.
                 # For example: template<typename T> int A<T>::var;
-                if not isSpecialization():
+                if not _is_specialization(templateParams, templateArgs):
                     templateArgs = None
 
         def matches(s: "Symbol") -> bool:
@@ -4839,14 +4877,23 @@ class Symbol:
                                  ourChild.declaration.directiveType, name)
                     logger.warning(msg, location=(otherChild.docname, otherChild.line))
                 else:
-                    # Both have declarations, and in the same docname.
+                    if (otherChild.declaration.objectType ==
-                    # This can apparently happen, it should be safe to
+                            ourChild.declaration.objectType and
-                    # just ignore it, right?
+                            otherChild.declaration.objectType in
-                    # Hmm, only on duplicate declarations, right?
+                            ('templateParam', 'functionParam')):
-                    msg = "Internal C++ domain error during symbol merging.\n"
+                        # `ourChild` was presumably just created during mergging
-                    msg += "ourChild:\n" + ourChild.to_string(1)
+                        # by the call to `_fill_empty` on the parent and can be
-                    msg += "\notherChild:\n" + otherChild.to_string(1)
+                        # ignored.
-                    logger.warning(msg, location=otherChild.docname)
+                        pass
+                    else:
+                        # Both have declarations, and in the same docname.
+                        # This can apparently happen, it should be safe to
+                        # just ignore it, right?
+                        # Hmm, only on duplicate declarations, right?
+                        msg = "Internal C++ domain error during symbol merging.\n"
+                        msg += "ourChild:\n" + ourChild.to_string(1)
+                        msg += "\notherChild:\n" + otherChild.to_string(1)
+                        logger.warning(msg, location=otherChild.docname)
             ourChild.merge_with(otherChild, docnames, env)
         if Symbol.debug_lookup:
             Symbol.debug_indent -= 2

tests/test_domain_cpp.py

@@ -841,9 +841,9 @@ def test_domain_cpp_ast_templates():
     check('class', 'abc::ns::foo{{id_0, id_1, ...id_2}} {key}xyz::bar',
           {2: 'I00DpEXN3abc2ns3fooEI4id_04id_1sp4id_2EEN3xyz3barE'})
     check('class', 'abc::ns::foo{{id_0, id_1, id_2}} {key}xyz::bar<id_0, id_1, id_2>',
-          {2: 'I000EXN3abc2ns3fooEI4id_04id_14id_2EEN3xyz3barI4id_04id_14id_2EE'})
+          {2: 'I000EXN3abc2ns3fooEI4id_04id_14id_2EEN3xyz3barE'})
     check('class', 'abc::ns::foo{{id_0, id_1, ...id_2}} {key}xyz::bar<id_0, id_1, id_2...>',
-          {2: 'I00DpEXN3abc2ns3fooEI4id_04id_1sp4id_2EEN3xyz3barI4id_04id_1Dp4id_2EE'})
+          {2: 'I00DpEXN3abc2ns3fooEI4id_04id_1sp4id_2EEN3xyz3barE'})
 
     check('class', 'template<> Concept{{U}} {key}A<int>::B', {2: 'IEI0EX7ConceptI1UEEN1AIiE1BE'})
 
@@ -901,7 +901,7 @@ def test_domain_cpp_ast_requires_clauses():
           'template<typename T> requires R<T> ' +
           'template<typename U> requires S<T> ' +
           'void A<T>::f() requires B',
-          {4: 'I0EIQ1RI1TEEI0EIQaa1SI1TE1BEN1AI1TE1fEvv'})
+          {4: 'I0EIQ1RI1TEEI0EIQaa1SI1TE1BEN1A1fEvv'})
     check('function',
           'template<template<typename T> requires R<T> typename X> ' +
           'void f()',
@@ -1395,3 +1395,89 @@ def test_domain_cpp_parse_mix_decl_duplicate(app, warning):
     assert "index.rst:3: WARNING: Duplicate C++ declaration, also defined at index:1." in ws[2]
     assert "Declaration is '.. cpp:struct:: A'." in ws[3]
     assert ws[4] == ""
+
+
+# For some reason, using the default testroot of "root" leads to the contents of
+# `test-root/objects.txt` polluting the symbol table depending on the test
+# execution order.  Using a testroot of "config" seems to avoid that problem.
+@pytest.mark.sphinx(testroot='config')
+def test_domain_cpp_normalize_unspecialized_template_args(make_app, app_params):
+    args, kwargs = app_params
+
+    text1 = (".. cpp:class:: template <typename T> A\n")
+    text2 = (".. cpp:class:: template <typename T> template <typename U> A<T>::B\n")
+
+    app1 = make_app(*args, **kwargs)
+    restructuredtext.parse(app=app1, text=text1, docname='text1')
+    root1 = app1.env.domaindata['cpp']['root_symbol']
+
+    assert root1.dump(1) == (
+        '  ::\n'
+        '    template<typename T> \n'
+        '    A: template<typename T> A\t(text1)\n'
+        '      T: typename T\t(text1)\n'
+    )
+
+    app2 = make_app(*args, **kwargs)
+    restructuredtext.parse(app=app2, text=text2, docname='text2')
+    root2 = app2.env.domaindata['cpp']['root_symbol']
+
+    assert root2.dump(1) == (
+        '  ::\n'
+        '    template<typename T> \n'
+        '    A\n'
+        '      T\n'
+        '      template<typename U> \n'
+        '      B: template<typename T> template<typename U> A<T>::B\t(text2)\n'
+        '        U: typename U\t(text2)\n'
+    )
+
+    root2.merge_with(root1, ['text1'], app2.env)
+
+    assert root2.dump(1) == (
+        '  ::\n'
+        '    template<typename T> \n'
+        '    A: template<typename T> A\t(text1)\n'
+        '      T: typename T\t(text1)\n'
+        '      template<typename U> \n'
+        '      B: template<typename T> template<typename U> A<T>::B\t(text2)\n'
+        '        U: typename U\t(text2)\n'
+    )
+    warning = app2._warning.getvalue()
+    assert 'Internal C++ domain error during symbol merging' not in warning
+
+
+def parse_template_parameter(param: str):
+    ast = parse('type', 'template<' + param + '> X')
+    return ast.templatePrefix.templates[0].params[0]
+
+
+@pytest.mark.parametrize(
+    'param,is_pack',
+    [('typename', False),
+     ('typename T', False),
+     ('typename...', True),
+     ('typename... T', True),
+     ('int', False),
+     ('int N', False),
+     ('int* N', False),
+     ('int& N', False),
+     ('int&... N', True),
+     ('int*... N', True),
+     ('int...', True),
+     ('int... N', True),
+     ('auto', False),
+     ('auto...', True),
+     ('int X::*', False),
+     ('int X::*...', True),
+     ('int (X::*)(bool)', False),
+     ('int (X::*x)(bool)', False),
+     # TODO: the following two declarations cannot currently be parsed
+     # ('int (X::*)(bool)...', True),
+     # ('int (X::*x...)(bool)', True),
+     ('template<typename> class', False),
+     ('template<typename> class...', True),
+     ])
+def test_domain_cpp_template_parameters_is_pack(param: str, is_pack: bool):
+    ast = parse_template_parameter(param)
+    assert ast.isPack == is_pack