[clang-tools-extra] [clang-tidy] Add performance-redundant-lookup check (PR #125420)
via cfe-commits
cfe-commits at lists.llvm.org
Sun Feb 2 08:47:37 PST 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang-tools-extra
Author: Balazs Benics (steakhal)
<details>
<summary>Changes</summary>
Finds redundant lookups to set|map containers.
For example: `map.count(key) && map[key] < threshold`
---
I've implemented this check in the Clang Static Analyzer, but it didn't really bring much value compared to its cost.
Because of this, I decided to have a second look and implement this in clang-tidy.
As in the [comment](https://github.com/llvm/llvm-project/issues/123376#issuecomment-2628966580) people showed interest, I decided to give a final polish to the check and publish it to ask for feedback.
My experience of this checker so far on the `clang` code base was that it didn't produce many false-positives, but those are hard to avoid due to what patterns we are looking for.
Frequently the findings were actionable and useful, and already fixed a couple issue that I found: 0e62c748d440a6d12d190e951c987efe309f40d6, 9333d8fb0749b1ae2b152a1003d2ecc00027b3d5, d0a142eaea03661e8399f2c1733b93d21d55dfee, 0d21ef4e6c50c7d4d591adf7e6dbd6232e8a99c4, 65708bad579229cd7f62b8d0eaefda4bb20eb6d8, 16d4453f2f5d9554ce39507fda0f33ce9066007b.
I've considered adding some fixits, and that may be possible if we focus on some really frequent patterns, but I decided not to invest there.
I've considered techniques to limit the scope of what "lookups" should be bundled together, for example the lookups that are in close proximity, or lookups that are within the same lexical scope, or there are no mutations between the lookups; but ultimately I found any of these arbitrary and confusing - though I admit, there could be improvements.
Let me know what you think.
---
Patch is 35.63 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/125420.diff
13 Files Affected:
- (modified) clang-tools-extra/clang-tidy/performance/CMakeLists.txt (+1)
- (modified) clang-tools-extra/clang-tidy/performance/PerformanceTidyModule.cpp (+3)
- (added) clang-tools-extra/clang-tidy/performance/RedundantLookupCheck.cpp (+159)
- (added) clang-tools-extra/clang-tidy/performance/RedundantLookupCheck.h (+46)
- (modified) clang-tools-extra/docs/ReleaseNotes.rst (+5)
- (modified) clang-tools-extra/docs/clang-tidy/checks/list.rst (+1)
- (added) clang-tools-extra/docs/clang-tidy/checks/performance/redundant-lookup.rst (+147)
- (added) clang-tools-extra/test/clang-tidy/checkers/Inputs/Headers/functional (+21)
- (added) clang-tools-extra/test/clang-tidy/checkers/Inputs/Headers/map (+167)
- (added) clang-tools-extra/test/clang-tidy/checkers/Inputs/Headers/memory (+10)
- (added) clang-tools-extra/test/clang-tidy/checkers/Inputs/Headers/set (+145)
- (added) clang-tools-extra/test/clang-tidy/checkers/Inputs/Headers/utility (+13)
- (added) clang-tools-extra/test/clang-tidy/checkers/performance/redundant-lookup.cpp (+142)
``````````diff
diff --git a/clang-tools-extra/clang-tidy/performance/CMakeLists.txt b/clang-tools-extra/clang-tidy/performance/CMakeLists.txt
index c6e547c5089fb0..6f907852c9fd1c 100644
--- a/clang-tools-extra/clang-tidy/performance/CMakeLists.txt
+++ b/clang-tools-extra/clang-tidy/performance/CMakeLists.txt
@@ -21,6 +21,7 @@ add_clang_library(clangTidyPerformanceModule STATIC
NoexceptMoveConstructorCheck.cpp
NoexceptSwapCheck.cpp
PerformanceTidyModule.cpp
+ RedundantLookupCheck.cpp
TriviallyDestructibleCheck.cpp
TypePromotionInMathFnCheck.cpp
UnnecessaryCopyInitialization.cpp
diff --git a/clang-tools-extra/clang-tidy/performance/PerformanceTidyModule.cpp b/clang-tools-extra/clang-tidy/performance/PerformanceTidyModule.cpp
index 9e0fa6f88b36a0..a613114e6b83bd 100644
--- a/clang-tools-extra/clang-tidy/performance/PerformanceTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/performance/PerformanceTidyModule.cpp
@@ -24,6 +24,7 @@
#include "NoexceptDestructorCheck.h"
#include "NoexceptMoveConstructorCheck.h"
#include "NoexceptSwapCheck.h"
+#include "RedundantLookupCheck.h"
#include "TriviallyDestructibleCheck.h"
#include "TypePromotionInMathFnCheck.h"
#include "UnnecessaryCopyInitialization.h"
@@ -62,6 +63,8 @@ class PerformanceModule : public ClangTidyModule {
"performance-noexcept-move-constructor");
CheckFactories.registerCheck<NoexceptSwapCheck>(
"performance-noexcept-swap");
+ CheckFactories.registerCheck<RedundantLookupCheck>(
+ "performance-redundant-lookup");
CheckFactories.registerCheck<TriviallyDestructibleCheck>(
"performance-trivially-destructible");
CheckFactories.registerCheck<TypePromotionInMathFnCheck>(
diff --git a/clang-tools-extra/clang-tidy/performance/RedundantLookupCheck.cpp b/clang-tools-extra/clang-tidy/performance/RedundantLookupCheck.cpp
new file mode 100644
index 00000000000000..fefb28682c5b8a
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/performance/RedundantLookupCheck.cpp
@@ -0,0 +1,159 @@
+//===--- RedundantLookupCheck.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 "RedundantLookupCheck.h"
+#include "../utils/OptionsUtils.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/Regex.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::performance {
+
+static constexpr auto DefaultContainerNameRegex = "set|map";
+
+static const llvm::StringRef DefaultLookupMethodNames =
+ llvm::StringLiteral( //
+ "at;"
+ "contains;"
+ "count;"
+ "find_as;"
+ "find;"
+ // These are tricky, as they take the "key" at different places.
+ // They sometimes bundle up the key and the value together in a pair.
+ // "emplace;"
+ // "insert_or_assign;"
+ // "insert;"
+ // "try_emplace;"
+ )
+ .drop_back(); // Drops the last semicolon.
+
+RedundantLookupCheck::RedundantLookupCheck(StringRef Name,
+ ClangTidyContext *Context)
+ : ClangTidyCheck(Name, Context),
+ ContainerNameRegex(
+ Options.get("ContainerNameRegex", DefaultContainerNameRegex)),
+ LookupMethodNames(utils::options::parseStringList(
+ Options.get("LookupMethodNames", DefaultLookupMethodNames))) {}
+
+void RedundantLookupCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
+ Options.store(Opts, "ContainerNameRegex", ContainerNameRegex);
+ Options.store(Opts, "LookupMethodNames",
+ utils::options::serializeStringList(LookupMethodNames));
+}
+
+namespace {
+/// Checks if any of the ends of the source range is in a macro expansion.
+AST_MATCHER(Expr, hasMacroSourceRange) {
+ SourceRange R = Node.getSourceRange();
+ return R.getBegin().isMacroID() || R.getEnd().isMacroID();
+}
+} // namespace
+
+static constexpr const char *ObjKey = "obj";
+static constexpr const char *LookupKey = "key";
+static constexpr const char *LookupCallKey = "lookup";
+static constexpr const char *EnclosingFnKey = "fn";
+
+void RedundantLookupCheck::registerMatchers(MatchFinder *Finder) {
+ auto MatchesContainerNameRegex =
+ matchesName(ContainerNameRegex, llvm::Regex::IgnoreCase);
+
+ // Match that the expression is a record type with a name that contains "map"
+ // or "set".
+ auto RecordCalledMapOrSet =
+ expr(ignoringImpCasts(hasType(hasUnqualifiedDesugaredType(recordType(
+ hasDeclaration(namedDecl(MatchesContainerNameRegex)))))))
+ .bind(ObjKey);
+
+ auto SubscriptCall =
+ cxxOperatorCallExpr(hasOverloadedOperatorName("[]"), argumentCountIs(2),
+ hasArgument(0, RecordCalledMapOrSet),
+ hasArgument(1, expr().bind(LookupKey)));
+
+ auto LookupMethodCalls =
+ cxxMemberCallExpr(on(RecordCalledMapOrSet), argumentCountIs(1),
+ hasArgument(0, expr().bind(LookupKey)),
+ callee(cxxMethodDecl(hasAnyName(LookupMethodNames))));
+
+ // Match any lookup or subscript calls that are not in a macro expansion.
+ auto AnyLookup = callExpr(unless(hasMacroSourceRange()),
+ anyOf(SubscriptCall, LookupMethodCalls))
+ .bind(LookupCallKey);
+
+ // We need to collect all lookups in a function to be able to report them in
+ // batches.
+ Finder->addMatcher(
+ functionDecl(hasBody(compoundStmt(forEachDescendant(AnyLookup))))
+ .bind(EnclosingFnKey),
+ this);
+}
+
+/// Hash the container object expr along with the key used for lookup and the
+/// enclosing function together.
+static unsigned hashLookupEvent(const ASTContext &Ctx,
+ const FunctionDecl *EnclosingFn,
+ const Expr *LookupKey,
+ const Expr *ContainerObject) {
+ llvm::FoldingSetNodeID ID;
+ ID.AddPointer(EnclosingFn);
+
+ LookupKey->Profile(ID, Ctx, /*Canonical=*/true,
+ /*ProfileLambdaExpr=*/true);
+ ContainerObject->Profile(ID, Ctx, /*Canonical=*/true,
+ /*ProfileLambdaExpr=*/true);
+ return ID.ComputeHash();
+}
+
+void RedundantLookupCheck::check(const MatchFinder::MatchResult &Result) {
+ SM = Result.SourceManager;
+
+ const auto *EnclosingFn =
+ Result.Nodes.getNodeAs<FunctionDecl>(EnclosingFnKey);
+ const auto *LookupCall = Result.Nodes.getNodeAs<CallExpr>(LookupCallKey);
+ const auto *Key = Result.Nodes.getNodeAs<Expr>(LookupKey);
+ const auto *ContainerObject = Result.Nodes.getNodeAs<Expr>(ObjKey);
+
+ unsigned LookupHash =
+ hashLookupEvent(*Result.Context, EnclosingFn, ContainerObject, Key);
+ auto &Lookups = RegisteredLookups.try_emplace(LookupHash).first->second;
+ if (!llvm::is_contained(Lookups, LookupCall))
+ Lookups.push_back(LookupCall);
+}
+
+void RedundantLookupCheck::onEndOfTranslationUnit() {
+ auto ByBeginLoc = [this](const CallExpr *Lookup1, const CallExpr *Lookup2) {
+ return SM->isBeforeInTranslationUnit(Lookup1->getBeginLoc(),
+ Lookup2->getBeginLoc());
+ };
+
+ // Process the found lookups of each function.
+ for (auto &LookupGroup : llvm::make_second_range(RegisteredLookups)) {
+ if (LookupGroup.size() < 2)
+ continue;
+
+ llvm::sort(LookupGroup, ByBeginLoc);
+
+ const CallExpr *FirstLookupCall = LookupGroup.front();
+ diag(FirstLookupCall->getBeginLoc(), "possibly redundant container lookups")
+ << FirstLookupCall->getSourceRange();
+
+ for (const CallExpr *LookupCall : llvm::drop_begin(LookupGroup)) {
+ diag(LookupCall->getBeginLoc(), "next lookup here", DiagnosticIDs::Note)
+ << LookupCall->getSourceRange();
+ }
+ }
+
+ RegisteredLookups.clear();
+}
+
+} // namespace clang::tidy::performance
diff --git a/clang-tools-extra/clang-tidy/performance/RedundantLookupCheck.h b/clang-tools-extra/clang-tidy/performance/RedundantLookupCheck.h
new file mode 100644
index 00000000000000..b37e1c2234c767
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/performance/RedundantLookupCheck.h
@@ -0,0 +1,46 @@
+//===--- RedundantLookupCheck.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_PERFORMANCE_REDUNDANTLOOKUPCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_PERFORMANCE_REDUNDANTLOOKUPCHECK_H
+
+#include "../ClangTidyCheck.h"
+#include "clang/AST/Expr.h"
+
+namespace clang {
+class SourceManager;
+} // namespace clang
+
+namespace clang::tidy::performance {
+
+/// Detects redundant container lookups.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/performance/redundant-lookup.html
+class RedundantLookupCheck : public ClangTidyCheck {
+public:
+ RedundantLookupCheck(StringRef Name, ClangTidyContext *Context);
+ void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+ void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+ void onEndOfTranslationUnit() override;
+ void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
+ bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
+ return LangOpts.CPlusPlus;
+ }
+
+private:
+ llvm::DenseMap<unsigned, llvm::SmallVector<const CallExpr *>>
+ RegisteredLookups;
+ const StringRef ContainerNameRegex;
+ const std::vector<StringRef> LookupMethodNames;
+ const SourceManager *SM = nullptr;
+};
+
+} // namespace clang::tidy::performance
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_PERFORMANCE_REDUNDANTLOOKUPCHECK_H
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 3bddeeda06e06b..2287e9f5caaf95 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -91,6 +91,11 @@ Improvements to clang-tidy
New checks
^^^^^^^^^^
+- New :doc:`performance-redundant-lookup
+ <clang-tidy/checks/performance/redundant-lookup>` check.
+
+ Detects redundant container lookups.
+
New check aliases
^^^^^^^^^^^^^^^^^
diff --git a/clang-tools-extra/docs/clang-tidy/checks/list.rst b/clang-tools-extra/docs/clang-tidy/checks/list.rst
index 7b9b905ef76715..43f3d147c4c309 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -344,6 +344,7 @@ Clang-Tidy Checks
:doc:`performance-noexcept-destructor <performance/noexcept-destructor>`, "Yes"
:doc:`performance-noexcept-move-constructor <performance/noexcept-move-constructor>`, "Yes"
:doc:`performance-noexcept-swap <performance/noexcept-swap>`, "Yes"
+ :doc:`performance-redundant-lookup <performance/redundant-lookup>`, "Yes"
:doc:`performance-trivially-destructible <performance/trivially-destructible>`, "Yes"
:doc:`performance-type-promotion-in-math-fn <performance/type-promotion-in-math-fn>`, "Yes"
:doc:`performance-unnecessary-copy-initialization <performance/unnecessary-copy-initialization>`, "Yes"
diff --git a/clang-tools-extra/docs/clang-tidy/checks/performance/redundant-lookup.rst b/clang-tools-extra/docs/clang-tidy/checks/performance/redundant-lookup.rst
new file mode 100644
index 00000000000000..6f25215e867ead
--- /dev/null
+++ b/clang-tools-extra/docs/clang-tidy/checks/performance/redundant-lookup.rst
@@ -0,0 +1,147 @@
+.. title:: clang-tidy - performance-redundant-lookup
+
+performance-redundant-lookup
+============================
+
+This check warns about potential redundant container lookup operations within
+a function.
+
+Examples
+--------
+
+.. code-block:: c++
+
+ if (map.count(key) && map[key] < threshold) {
+ // do stuff
+ }
+
+In this example, we would check if the key is present in the map,
+and then do a second lookup to actually load the value.
+We could refactor the code into this, to use a single lookup:
+
+.. code-block:: c++
+
+ if (auto it = map.find(key); it != map.end() && it->second < threshold) {
+ // do stuff
+ }
+
+In this example, we do three lookups while calculating, caching and then
+using the result of some expensive computation:
+
+.. code-block:: c++
+
+ if (!cache.contains(key)) {
+ cache[key] = computeExpensiveValue();
+ }
+ use(cache[key]);
+
+We could refactor this code using ``try_emplace`` to fill up the cache entry
+if wasn't present, and just use it if we already computed the value.
+This way we would only have a single unavoidable lookup:
+
+.. code-block:: c++
+
+ auto [cacheSlot, inserted] cache.try_emplace(key);
+ if (inserted) {
+ cacheSlot->second = computeExpensiveValue();
+ }
+ use(cacheSlot->second);
+
+
+What is a "lookup"?
+-------------------
+
+All container operations that walk the internal structure of the container
+should be considered as "lookups".
+This means that checking if an element is present or inserting an element
+is also considered as a "lookup".
+
+For example, ``contains``, ``count`` but even the ``operator[]``
+should be considered as "lookups".
+
+Technically ``insert``, ``emplace`` or ``try_emplace``are also lookups,
+even if due to limitations, they are not recognized as such.
+
+Lookups inside macros are ignored, thus not considered as "lookups".
+For example:
+
+.. code-block:: c++
+
+ assert(map.count(key) == 0); // Not considered as a "lookup".
+
+Limitations
+-----------
+
+ - The "redundant lookups" may span across a large chunk of code.
+ Such reports can be considered as false-positives because it's hard to judge
+ if the container is definitely not mutated between the lookups.
+ It would be hard to split the lookup groups in a stable and meaningful way,
+ and a threshold for proximity would be just an arbitrary limit.
+
+ - The "redundant lookups" may span across different control-flow constructs,
+ making it impossible to refactor.
+ It may be that the code was deliberately structured like it was, thus the
+ report is considered a false-positive.
+ Use your best judgement to see if anything needs to be fixed or not.
+ For example:
+
+ .. code-block:: c++
+
+ if (coin())
+ map[key] = foo();
+ else
+ map[key] = bar();
+
+ Could be refactored into:
+
+ .. code-block:: c++
+
+ map[key] = coin() ? foo() : bar();
+
+ However, the following code could be considered intentional:
+
+ .. code-block:: c++
+
+ // Handle the likely case.
+ if (auto it = map.find(key); it != map.end()) {
+ return process(*it);
+ }
+
+ // Commit the dirty items, and check again.
+ for (const auto &item : dirtyList) {
+ commit(item, map); // Updates the "map".
+ }
+
+ // Do a final check.
+ if (auto it = map.find(key); it != map.end()) {
+ return process(*it);
+ }
+
+ - The key argument of a lookup may have sideffects. Sideffects are ignored when identifying lookups.
+ This can introduce some false-positives. For example:
+
+ .. code-block:: c++
+
+ m.contains(rng(++n));
+ m.contains(rng(++n)); // FP: This is considered a redundant lookup.
+
+ - Lookup member functions must have exactly 1 argument to match.
+ There are technically lookup functions, such as ``insert`` or ``try_emplace``,
+ but it would be hard to identify the "key" part of the argument,
+ while leaving the implementation open for user-configuration via the
+ ``LookupMethodNames`` option.
+
+Options
+-------
+
+.. option:: ContainerNameRegex
+
+ The regular expression matching the type of the container objects.
+ This is matched in a case insensitive manner.
+ Default is ``set|map``.
+
+.. option:: LookupMethodNames
+
+ Member function names to consider as **lookup** operation.
+ These methods must have exactly 1 argument.
+ Default is ``at;contains;count;find_as;find``.
diff --git a/clang-tools-extra/test/clang-tidy/checkers/Inputs/Headers/functional b/clang-tools-extra/test/clang-tidy/checkers/Inputs/Headers/functional
new file mode 100644
index 00000000000000..be845b3c7e68a7
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/checkers/Inputs/Headers/functional
@@ -0,0 +1,21 @@
+#ifndef _FUNCTIONAL_
+#define _FUNCTIONAL_
+
+namespace std {
+
+template <class T> struct less {
+ constexpr bool operator()(const T& Lhs, const T& Rhs) const {
+ return Lhs < Rhs;
+ }
+};
+
+template <> struct less<void> {
+ template <typename T, typename U>
+ constexpr bool operator()(T &&Lhs, U &&Rhs) const {
+ return static_cast<T &&>(Lhs) < static_cast<U &&>(Rhs);
+ }
+};
+
+} // namespace std
+
+#endif // _FUNCTIONAL_
diff --git a/clang-tools-extra/test/clang-tidy/checkers/Inputs/Headers/map b/clang-tools-extra/test/clang-tidy/checkers/Inputs/Headers/map
new file mode 100644
index 00000000000000..1c7b26c93f7270
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/checkers/Inputs/Headers/map
@@ -0,0 +1,167 @@
+#ifndef _MAP_
+#define _MAP_
+
+#include <functional> // std::less
+#include <memory> // std::allocator
+#include <utility> // std::pair
+
+namespace std {
+
+using size_t = decltype(sizeof(0));
+using ptrdiff_t = decltype(static_cast<int*>(nullptr) - static_cast<int*>(nullptr));
+
+template<
+ class Key,
+ class T,
+ class Compare = std::less<Key>,
+ class Allocator = std::allocator<std::pair<const Key, T>>
+> class map {
+public:
+ using key_type = Key;
+ using mapped_type = T;
+ using value_type = std::pair<const Key, T>;
+ using size_type = size_t;
+ using difference_type = ptrdiff_t;
+ using key_compare = Compare;
+ using allocator_type = Allocator;
+ using reference = value_type&;
+ using const_reference = const value_type&;
+
+ map();
+ explicit map(const Allocator&);
+ template <class InputIt>
+ map(InputIt, InputIt, const Compare& = Compare(), const Allocator& = Allocator());
+ template <class InputIt> map(InputIt, InputIt, const Allocator&);
+ map(const map&, const Allocator&);
+ map(map&&, const Allocator&);
+ // missing: init-list ctors
+ // missing: from_range ctors
+
+ ~map();
+
+ map& operator=(const map&);
+ map& operator=(map&&);
+
+ T& at(const Key&);
+ const T& at(const Key&) const;
+ template <class K> T& at(const K&); // C++26
+ template <class K> const T& at(const K&) const; // C++26
+
+ T& operator[](const Key&);
+ T& operator[](Key&&);
+ template <class K> T& operator[](K&&); // C++26
+
+ struct iterator {};
+ struct const_iterator {};
+
+ iterator begin();
+ const_iterator begin() const;
+ const_iterator cbegin() const noexcept;
+
+ iterator end();
+ const_iterator end() const;
+ const_iterator cend() const noexcept;
+
+ iterator rbegin();
+ const_iterator rbegin() const;
+ const_iterator crbegin() const noexcept;
+
+ iterator rend();
+ const_iterator rend() const;
+ const_iterator crend() const noexcept;
+
+ bool empty() const;
+ size_type size() const;
+ size_type max_size() const;
+ void clear();
+
+ std::pair<iterator, bool> insert(const value_type&);
+ template <class P> std::pair<iterator, bool> insert(P&&);
+ std::pair<iterator, bool> insert(value_type&&);
+ iterator insert(const_iterator, const value_type&);
+ iterator insert(const_iterator, value_type&&);
+ template <class InputIt> void insert(InputIt, InputIt);
+ // void insert(std::initializer_list<value_type>);
+ // insert_return_type insert(node_type&&);
+ // iterator insert(const_iterator, node_type&&);
+
+ template <class R> void insert_range(R&&); // C++23
+
+ template <class M> std::pair<iterator, bool> insert_or_assign(const Key&, M&&);
+ template <class M> std::pair<iterator, bool> insert_or_assign(Key&&, M&&);
+ template <class K, class M> std::pair<iterator, bool> insert_or_assign(K&&, M&&); // C++26
+ template <class M> iterator insert_or_assign(const_iterator, const Key&, M&&);
+ template <class M> iterator...
[truncated]
``````````
</details>
https://github.com/llvm/llvm-project/pull/125420
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