[clang-tools-extra] 3adaa97 - Fix ForRangeCopyCheck not triggering on iterators returning elements by value in C++17.
Dmitri Gribenko via cfe-commits
cfe-commits at lists.llvm.org
Wed May 6 00:44:29 PDT 2020
Author: Dmitri Gribenko
Date: 2020-05-06T09:42:13+02:00
New Revision: 3adaa97f0157e9d274c4d4e69b733db75b963574
URL: https://github.com/llvm/llvm-project/commit/3adaa97f0157e9d274c4d4e69b733db75b963574
DIFF: https://github.com/llvm/llvm-project/commit/3adaa97f0157e9d274c4d4e69b733db75b963574.diff
LOG: Fix ForRangeCopyCheck not triggering on iterators returning elements by value in C++17.
Summary:
The AST is different in C++17 in that there is no MaterializeTemporaryExpr for in the AST for a loop variable that is initialized from an iterator that returns its elements by value.
Account for this by checking that the variable is not initialized by an operator* call that returns a value type.
Reviewers: gribozavr2
Reviewed By: gribozavr2
Subscribers: cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D79440
Added:
Modified:
clang-tools-extra/clang-tidy/performance/ForRangeCopyCheck.cpp
clang-tools-extra/test/clang-tidy/checkers/performance-for-range-copy.cpp
Removed:
################################################################################
diff --git a/clang-tools-extra/clang-tidy/performance/ForRangeCopyCheck.cpp b/clang-tools-extra/clang-tidy/performance/ForRangeCopyCheck.cpp
index 579d4fa3d786..38dba7b89707 100644
--- a/clang-tools-extra/clang-tidy/performance/ForRangeCopyCheck.cpp
+++ b/clang-tools-extra/clang-tidy/performance/ForRangeCopyCheck.cpp
@@ -37,12 +37,18 @@ void ForRangeCopyCheck::registerMatchers(MatchFinder *Finder) {
// Match loop variables that are not references or pointers or are already
// initialized through MaterializeTemporaryExpr which indicates a type
// conversion.
- auto LoopVar = varDecl(
- hasType(qualType(
- unless(anyOf(hasCanonicalType(anyOf(referenceType(), pointerType())),
- hasDeclaration(namedDecl(
- matchers::matchesAnyListedName(AllowedTypes))))))),
- unless(hasInitializer(expr(hasDescendant(materializeTemporaryExpr())))));
+ auto HasReferenceOrPointerTypeOrIsAllowed = hasType(qualType(
+ unless(anyOf(hasCanonicalType(anyOf(referenceType(), pointerType())),
+ hasDeclaration(namedDecl(
+ matchers::matchesAnyListedName(AllowedTypes)))))));
+ auto IteratorReturnsValueType = cxxOperatorCallExpr(
+ hasOverloadedOperatorName("*"),
+ callee(
+ cxxMethodDecl(returns(unless(hasCanonicalType(referenceType()))))));
+ auto LoopVar =
+ varDecl(HasReferenceOrPointerTypeOrIsAllowed,
+ unless(hasInitializer(expr(hasDescendant(expr(anyOf(
+ materializeTemporaryExpr(), IteratorReturnsValueType)))))));
Finder->addMatcher(cxxForRangeStmt(hasLoopVariable(LoopVar.bind("loopVar")))
.bind("forRange"),
this);
diff --git a/clang-tools-extra/test/clang-tidy/checkers/performance-for-range-copy.cpp b/clang-tools-extra/test/clang-tidy/checkers/performance-for-range-copy.cpp
index e51142161ed9..e22650e10198 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/performance-for-range-copy.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/performance-for-range-copy.cpp
@@ -28,6 +28,7 @@ struct Iterator {
};
template <typename T>
struct View {
+ View() = default;
T begin() { return T(); }
T begin() const { return T(); }
T end() { return T(); }
@@ -270,3 +271,28 @@ void IgnoreLoopVariableNotUsedInLoopBody() {
for (auto _ : View<Iterator<S>>()) {
}
}
+
+template <typename T>
+struct ValueReturningIterator {
+ void operator++() {}
+ T operator*() { return T(); }
+ bool operator!=(const ValueReturningIterator &) { return false; }
+ typedef const T &const_reference;
+};
+
+void negativeValueIterator() {
+ // Check does not trigger for iterators that return elements by value.
+ for (const S SS : View<ValueReturningIterator<S>>()) {
+ }
+}
+
+View<Iterator<S>> createView(S) { return View<Iterator<S>>(); }
+
+void positiveValueIteratorUsedElseWhere() {
+ for (const S SS : createView(*ValueReturningIterator<S>())) {
+ // CHECK-MESSAGES: [[@LINE-1]]:16: warning: the loop variable's type is not
+ // a reference type; this creates a copy in each iteration; consider making
+ // this a reference [performance-for-range-copy] CHECK-FIXES: for (const S&
+ // SS : createView(*ValueReturningIterator<S>())) {
+ }
+}
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