// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// Test for template specializations.
//
// In template specializations template parameters (e.g. |T| or |T2| in
// MyTemplate below) get substituted with an actual class (e.g. |SomeClass| or
// |int|). In an *implicit* specialization, these substitutions are "overlaid"
// / "overimposed" on top of the template definition and this can lead to
// generating conflicting replacements - for example the same |t_ptr_field|
// definition can get replaced with:
// 1. T* t_ptr_field -> raw_ptr<T> t_ptr_field // expected
// 2. T* t_ptr_field -> raw_ptr<SomeClass> t_ptr_field // undesired
//
// To avoid generating conflicting replacements, the rewriter excludes implicit
// template specializations via |implicit_field_decl_matcher|.
//
// Note that rewrites in *explicit* template specializations are still
// desirable. For example, see the |T2* t2_ptr_field| in |MyTemplate<int, T2>|
// partial template specialization.
#include <optional>
#include "base/containers/span.h"
#include "base/memory/raw_ptr.h"
#include "base/memory/raw_span.h"
class SomeClass;
class SomeClass2;
template <typename T, typename T2>
class MyTemplate {
// Expected rewrite: raw_ptr<T> t_ptr_field;
raw_ptr<T> t_ptr_field;
// Expected rewrite: raw_ptr<SomeClass> some_class_ptr_field;
raw_ptr<SomeClass> some_class_ptr_field;
// No rewrite expected.
int int_field;
// Expected rewrite: base::raw_span<T> span_field1;
base::raw_span<T> span_field1;
// Expected rewrite: base::raw_span<SomeClass> span_field2;
base::raw_span<SomeClass> span_field2;
// Expected rewrite: std::optional<base::raw_span<T>> optional_span_field1;
std::optional<base::raw_span<T>> optional_span_field1;
// Expected rewrite: std::optional<base::raw_span<SomeClass>>
// optional_span_field2;
std::optional<base::raw_span<SomeClass>> optional_span_field2;
};
// Partial *explicit* specialization.
template <typename T2>
class MyTemplate<int, T2> {
// Expected rewrite: raw_ptr<T2> t2_ptr_field;
raw_ptr<T2> t2_ptr_field;
// Expected rewrite: raw_ptr<SomeClass> some_class_ptr_field;
raw_ptr<SomeClass> some_class_ptr_field;
// Expected rewrite: raw_ptr<int> int_ptr_field;
raw_ptr<int> int_ptr_field;
// No rewrite expected.
int int_field;
// Expected rewrite: base::raw_span<T2> span_field1;
base::raw_span<T2> span_field1;
// Expected rewrite: base::raw_span<SomeClass> span_field2;
base::raw_span<SomeClass> span_field2;
// Expected rewrite: std::optional<base::raw_span<int>> optional_span_field1;
std::optional<base::raw_span<int>> optional_span_field1;
// Expected rewrite: std::optional<base::raw_span<T2>> optional_span_field2;
std::optional<base::raw_span<T2>> optional_span_field2;
};
// Full *explicit* specialization.
template <>
class MyTemplate<int, SomeClass2> {
// Expected rewrite: raw_ptr<int> int_ptr_field;
raw_ptr<int> int_ptr_field;
// Expected rewrite: raw_ptr<SomeClass2> some_class2_ptr_field;
raw_ptr<SomeClass2> some_class2_ptr_field;
// No rewrite expected.
int int_field;
// Expected rewrite: base::raw_span<T2> span_field1;
base::raw_span<int> span_field1;
// Expected rewrite: base::raw_span<SomeClass> span_field2;
base::raw_span<SomeClass2> span_field2;
// Expected rewrite: std::optional<base::raw_span<int>> optional_span_field1;
std::optional<base::raw_span<int>> optional_span_field1;
// Expected rewrite: std::optional<base::raw_span<T2>> optional_span_field2;
std::optional<base::raw_span<SomeClass2>> optional_span_field2;
};
// The class definitions below trigger an implicit template specialization of
// MyTemplate.
class TemplateDerived : public MyTemplate<SomeClass, int> {};
class TemplateDerived2 : public MyTemplate<SomeClass2, int> {};
// Test where excluding SubstTemplateTypeParmType pointees is not sufficient,
// because the pointee is not |T|, but |TemplateSelfPointerTest<T>| like in
// the fields below.
//
// This test forces using
// classTemplateSpecializationDecl(isImplicitSpecialization())
// in the definition of |implicit_field_decl_matcher|.
// Note that no |hasAncestor| matcher is necessary - compare with
// nested_iterator_test below.
namespace self_pointer_test {
template <typename T>
class TemplateSelfPointerTest {
// Early versions of the rewriter used to rewrite the type below to three
// conflicting replacements:
// 1. raw_ptr<TemplateSelfPointerTest<bool>>
// 2. raw_ptr<TemplateSelfPointerTest<SomeClass2>>
// 3. raw_ptr<TemplateSelfPointerTest<T>>
//
// Something similar would have happened in //base/scoped_generic.h (in the
// nested Receiver class):
// ScopedGeneric* scoped_generic_;
//
// Expected rewrite: raw_ptr<TemplateSelfPointerTest<T>>
raw_ptr<TemplateSelfPointerTest<T>> ptr_field_;
// Similar test to the above. Something similar would have happened in
// //base/id_map.h (in the nested Iterator class):
// IDMap<V, K>* map_;
//
// Expected rewrite: raw_ptr<TemplateSelfPointerTest<T>>
raw_ptr<TemplateSelfPointerTest<T>> ptr_field2_;
// Expected rewrite: base::raw_span<TemplateSelfPointerTest> span_field1;
base::raw_span<TemplateSelfPointerTest> span_field1;
// Expected rewrite: base::raw_span<TemplateSelfPointerTest<T>> span_field2;
base::raw_span<TemplateSelfPointerTest<T>> span_field2;
// Expected rewrite: std::optional<base::raw_span<TemplateSelfPointerTest>>
// optional_span_field1;
std::optional<base::raw_span<TemplateSelfPointerTest>> optional_span_field1;
// Expected rewrite: std::optional<base::raw_span<TemplateSelfPointerTest<T>>>
// optional_span_field2;
std::optional<base::raw_span<TemplateSelfPointerTest<T>>>
optional_span_field2;
};
void foo() {
// Variable declarations below trigger an implicit template specialization of
// TemplateSelfPointerTest.
TemplateSelfPointerTest<bool> foo;
TemplateSelfPointerTest<SomeClass2> bar;
}
} // namespace self_pointer_test
// Test against overlapping replacement that occurred in Chromium in places
// like:
// - //components/url_pattern_index/string_splitter.h
// |const StringSplitter* splitter_| in nested Iterator class
// - //base/callback_list.h
// |CallbackListBase<CallbackType>* list_| in nested Iterator class
// - //mojo/public/cpp/bindings/receiver_set.h
// |ReceiverSetBase* const receiver_set_| in nested Entry class
//
// This test forces using
// hasAncestor(classTemplateSpecializationDecl(isImplicitSpecialization()))
// in the definition of |implicit_field_decl_matcher|.
namespace nested_iterator_test {
template <typename T>
class StringSplitter {
public:
class Iterator {
public:
Iterator(const StringSplitter& splitter) : splitter_(&splitter) {}
private:
// Danger of an overlapping replacement (when substituting
// |StringSplitter<T>| for |StringSplitter<int>| in an implicit template
// specialization triggered by the |foo2| function below.
//
// Expected rewrite: raw_ptr<const StringSplitter<T>> splitter_
raw_ptr<const StringSplitter<T>> splitter_;
// Expected rewrite: base::raw_span<const StringSplitter> span_field
base::raw_span<const StringSplitter> span_field;
};
Iterator begin() const { return Iterator(*this); }
};
void foo2() {
StringSplitter<int> splitter;
auto iterator = splitter.begin();
}
} // namespace nested_iterator_test
// Example based on base/trace_event/memory_usage_estimator.h where a function
// template |EstimateMemoryUsage| had a nested struct |SharedPointer| definition
// with a pointer field |value| that was leading to conflicting replacements.
namespace template_function {
template <typename T>
void foo(T* arg) {
struct NestedStruct {
// Expected rewrite: raw_ptr<T> ptr_field;
raw_ptr<T> ptr_field;
// Expected rewrite: raw_ptr<MyTemplate<T, T>> ptr_field2;
raw_ptr<MyTemplate<T, T>> ptr_field2;
// Expected rewrite: base::raw_span<T> span_field;
base::raw_span<T> span_field;
} var;
var.ptr_field = nullptr;
}
void bar() {
// Triggering implicit specializations of foo that in the past led the
// rewriter to generate conflicting replacements.
int i = 123;
SomeClass* p = nullptr;
foo(p);
foo(&i);
}
} // namespace template_function
Codebase Browser
chromium