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Find undefined container usage due to std::allocator<const T>. This is
unsupported in libstdc++ and may be unsupported in future libc++ (D120996
<https://reviews.llvm.org/D120996>). See
docs/clang-tidy/checks/portability-std-allocator-const-t.rst for detail.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D123655
Files:
clang-tools-extra/clang-tidy/portability/CMakeLists.txt
clang-tools-extra/clang-tidy/portability/PortabilityTidyModule.cpp
clang-tools-extra/clang-tidy/portability/StdAllocatorConstTCheck.cpp
clang-tools-extra/clang-tidy/portability/StdAllocatorConstTCheck.h
clang-tools-extra/docs/ReleaseNotes.rst
clang-tools-extra/docs/clang-tidy/checks/list.rst
clang-tools-extra/docs/clang-tidy/checks/portability-std-allocator-const-t.rst
clang-tools-extra/test/clang-tidy/checkers/portability-std-allocator-const-t.cpp
Index: clang-tools-extra/test/clang-tidy/checkers/portability-std-allocator-const-t.cpp
===================================================================
--- /dev/null
+++ clang-tools-extra/test/clang-tidy/checkers/portability-std-allocator-const-t.cpp
@@ -0,0 +1,72 @@
+// RUN: %check_clang_tidy -std=c++11-or-later %s portability-std-allocator-const-t %t --
+
+namespace std {
+typedef unsigned size_t;
+
+template <class T>
+class allocator {};
+template <class T>
+class hash {};
+template <class T>
+class equal_to {};
+template <class T>
+class less {};
+
+template <class T, class A = std::allocator<T>>
+class deque {};
+template <class T, class A = std::allocator<T>>
+class forward_list {};
+template <class T, class A = std::allocator<T>>
+class list {};
+template <class T, class A = std::allocator<T>>
+class vector {};
+
+template <class K, class C = std::less<K>, class A = std::allocator<K>>
+class multiset {};
+template <class K, class C = std::less<K>, class A = std::allocator<K>>
+class set {};
+
+template <class T, class C = std::deque<T>>
+class stack {};
+} // namespace std
+
+namespace absl {
+template <class K, class H = std::hash<K>, class Eq = std::equal_to<K>, class A = std::allocator<K>>
+class flat_hash_set {};
+} // namespace absl
+
+template <class T>
+class allocator {};
+
+void simple(std::vector<const char> a) {
+ // CHECK-MESSAGES: [[#@LINE-1]]:13: warning: container using std::allocator<const T> is undefined; remove const to work with libstdc++ and future libc++ [portability-std-allocator-const-t]
+ std::deque<const short> d;
+ // CHECK-MESSAGES: [[#@LINE-1]]:3: warning: container
+ std::list<const long> l;
+ // CHECK-MESSAGES: [[#@LINE-1]]:3: warning: container
+
+ std::multiset<int *const> ms;
+ // CHECK-MESSAGES: [[#@LINE-1]]:3: warning: container
+ std::set<const std::hash<int>> s;
+ // CHECK-MESSAGES: [[#@LINE-1]]:3: warning: container
+
+ absl::flat_hash_set<const int> fhs;
+ // CHECK-MESSAGES: [[#@LINE-1]]:3: warning: container
+
+ std::vector<int> neg0;
+ std::vector<const int *> neg1; // not const T
+ std::vector<const int, allocator<const int>> neg2; // not use std::allocator<const T>
+ std::forward_list<const int> forward; // rare, don't bother
+ std::stack<const int> stack; // not caught, but rare
+}
+
+template <class T>
+void temp() {
+ std::vector<const T> v;
+ // CHECK-MESSAGES: [[#@LINE-1]]:3: warning: container
+
+ std::vector<T> neg;
+}
+void use_temp() {
+ temp<int>();
+}
Index: clang-tools-extra/docs/clang-tidy/checks/portability-std-allocator-const-t.rst
===================================================================
--- /dev/null
+++ clang-tools-extra/docs/clang-tidy/checks/portability-std-allocator-const-t.rst
@@ -0,0 +1,22 @@
+.. title:: clang-tidy - portability-std-allocator-const-t
+
+portability-std-allocator-const-t
+=================================
+
+Per C++ ``[allocator.requirements.general]``: "T is any cv-unqualified object
+type", ``std::allocator<const T>`` is undefined. Many standard containers use
+``std::allocator`` by default and therefore their ``const T`` instantiations are
+undefined.
+
+libstdc++ never supports ``std::allocator<const T>`` and containers using them.
+Since GCC 8.0 (`PR48101 <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48101>`),
+there is a better diagnostic for some containers.
+
+.. code:: c++
+
+ std::deque<const int> deque; // error: static assertion failed: std::deque must have a non-const, non-volatile value_type
+ std::set<const int> set; // error: static assertion failed: std::set must have a non-const, non-volatile value_type
+ std::vector<int* const> vector; // error: static assertion failed: std::vector must have a non-const, non-volatile value_type
+
+However, code bases not compiled with libstdc++ may accrue such undefined usage.
+This check finds such code and prevents backsliding while clean-up is ongoing.
Index: clang-tools-extra/docs/clang-tidy/checks/list.rst
===================================================================
--- clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -289,6 +289,7 @@
`performance-unnecessary-value-param <performance-unnecessary-value-param.html>`_, "Yes"
`portability-restrict-system-includes <portability-restrict-system-includes.html>`_, "Yes"
`portability-simd-intrinsics <portability-simd-intrinsics.html>`_,
+ `portability-std-allocator-const-t <portability-std-allocator-const-t.html>`_,
`readability-avoid-const-params-in-decls <readability-avoid-const-params-in-decls.html>`_, "Yes"
`readability-braces-around-statements <readability-braces-around-statements.html>`_, "Yes"
`readability-const-return-type <readability-const-return-type.html>`_, "Yes"
Index: clang-tools-extra/docs/ReleaseNotes.rst
===================================================================
--- clang-tools-extra/docs/ReleaseNotes.rst
+++ clang-tools-extra/docs/ReleaseNotes.rst
@@ -117,6 +117,10 @@
Replaces groups of adjacent macros with an unscoped anonymous enum.
+- New :doc:`portability-std-allocator-t <clang-tidy/checks/portability-std-allocator-const-t>` check.
+
+ Find undefined container usage due to ``std::allocator<const T>``.
+
New check aliases
^^^^^^^^^^^^^^^^^
Index: clang-tools-extra/clang-tidy/portability/StdAllocatorConstTCheck.h
===================================================================
--- /dev/null
+++ clang-tools-extra/clang-tidy/portability/StdAllocatorConstTCheck.h
@@ -0,0 +1,36 @@
+//===--- StdAllocatorConstT.h - clang-tidy -----------------------*- C++-*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_PORTABILITY_STDALLOCATORCONSTTCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_PORTABILITY_STDALLOCATORCONSTTCHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang {
+namespace tidy {
+namespace portability {
+
+/// Find undefined container usage due to std::allocator<const T>. This is
+/// unsupported in libstdc++ (all versions) and future libc++.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/portability-std-allocator-const-t.html
+class StdAllocatorConstTCheck : public ClangTidyCheck {
+public:
+ StdAllocatorConstTCheck(StringRef Name, ClangTidyContext *Context)
+ : ClangTidyCheck(Name, Context) {}
+
+ void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+ void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+};
+
+} // namespace portability
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_PORTABILITY_STDALLOCATORCONSTTCHECK_H
Index: clang-tools-extra/clang-tidy/portability/StdAllocatorConstTCheck.cpp
===================================================================
--- /dev/null
+++ clang-tools-extra/clang-tidy/portability/StdAllocatorConstTCheck.cpp
@@ -0,0 +1,55 @@
+//===-- StdAllocatorConstTCheck.cpp - clang-tidy --------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "StdAllocatorConstTCheck.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace portability {
+
+void StdAllocatorConstTCheck::registerMatchers(MatchFinder *Finder) {
+ // Match std::allocator<const T>.
+ internal::BindableMatcher<Type> AllocatorConstT =
+ recordType(hasDeclaration(classTemplateSpecializationDecl(
+ hasName("::std::allocator"),
+ hasTemplateArgument(0, refersToType(qualType(isConstQualified()))))));
+
+ // Match `std::vector<const T> var;` and other common containers like deque,
+ // list, and absl::flat_hash_set. Some containers like forward_list, queue,
+ // and stack are not caught. Don't bother with std::unordered_set<const T>
+ // since libc++ does not allow it.
+ Finder->addMatcher(
+ varDecl(
+ hasType(hasUnqualifiedDesugaredType(
+ recordType(hasDeclaration(classTemplateSpecializationDecl(
+ hasAnyName("::std::vector", "::std::deque", "::std::list",
+ "::std::multiset", "::std::set",
+ "::absl::flat_hash_set"),
+ anyOf(hasTemplateArgument(1, refersToType(AllocatorConstT)),
+ hasTemplateArgument(2, refersToType(AllocatorConstT)),
+ hasTemplateArgument(
+ 3, refersToType(AllocatorConstT)))))))))
+ .bind("var"),
+ this);
+}
+
+void StdAllocatorConstTCheck::check(const MatchFinder::MatchResult &Result) {
+ const auto *Var = Result.Nodes.getNodeAs<VarDecl>("var");
+ if (!Var)
+ return;
+ diag(Var->getBeginLoc(),
+ "container using std::allocator<const T> is "
+ "undefined; remove const to work with libstdc++ and future libc++");
+}
+
+} // namespace portability
+} // namespace tidy
+} // namespace clang
Index: clang-tools-extra/clang-tidy/portability/PortabilityTidyModule.cpp
===================================================================
--- clang-tools-extra/clang-tidy/portability/PortabilityTidyModule.cpp
+++ clang-tools-extra/clang-tidy/portability/PortabilityTidyModule.cpp
@@ -11,6 +11,7 @@
#include "../ClangTidyModuleRegistry.h"
#include "RestrictSystemIncludesCheck.h"
#include "SIMDIntrinsicsCheck.h"
+#include "StdAllocatorConstTCheck.h"
namespace clang {
namespace tidy {
@@ -23,6 +24,8 @@
"portability-restrict-system-includes");
CheckFactories.registerCheck<SIMDIntrinsicsCheck>(
"portability-simd-intrinsics");
+ CheckFactories.registerCheck<StdAllocatorConstTCheck>(
+ "portability-std-allocator-const-t");
}
};
Index: clang-tools-extra/clang-tidy/portability/CMakeLists.txt
===================================================================
--- clang-tools-extra/clang-tidy/portability/CMakeLists.txt
+++ clang-tools-extra/clang-tidy/portability/CMakeLists.txt
@@ -7,6 +7,7 @@
PortabilityTidyModule.cpp
RestrictSystemIncludesCheck.cpp
SIMDIntrinsicsCheck.cpp
+ StdAllocatorConstTCheck.cpp
LINK_LIBS
clangTidy
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