intel/llvm
1
0
Fork 0
mirror of https://github.com/intel/llvm.git synced 2026-01-23 16:06:39 +08:00
Code Issues Packages Projects Releases Wiki Activity

[clang-tidy]performance-unnecessary-copy-initialization: fix false negative

Browse Source 
We're missing all cases where the return value is a type alias.

Unfortunately, this includes things we care about, such as
`std::vector<T>::operator[]` (return value is `const_reference`,
not `const T&`).

Match the canonical type instead.

Differential Revision: https://reviews.llvm.org/D112722
This commit is contained in:
Clement Courbet
2021-10-28 16:48:53 +02:00
parent a21a6ed8c2
commit fc1b24d736
2 changed files with 15 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
View File

@@ -84,7 +84,8 @@ AST_MATCHER_FUNCTION_P(StatementMatcher, isConstRefReturningMethodCall,
// returned either points to a global static variable or to a member of the
// called object.
return cxxMemberCallExpr(
callee(cxxMethodDecl(returns(matchers::isReferenceToConst()))
callee(cxxMethodDecl(
returns(hasCanonicalType(matchers::isReferenceToConst())))
.bind(MethodDeclId)),
on(declRefExpr(to(
varDecl(
@@ -97,7 +98,8 @@ AST_MATCHER_FUNCTION(StatementMatcher, isConstRefReturningFunctionCall) {
// Only allow initialization of a const reference from a free function if it
// has no arguments. Otherwise it could return an alias to one of its
// arguments and the arguments need to be checked for const use as well.
return callExpr(callee(functionDecl(returns(matchers::isReferenceToConst()))
return callExpr(callee(functionDecl(returns(hasCanonicalType(
matchers::isReferenceToConst())))
.bind(FunctionDeclId)),
argumentCountIs(0), unless(callee(cxxMethodDecl())))
.bind(InitFunctionCallId);

11
clang-tools-extra/test/clang-tidy/checkers/performance-unnecessary-copy-initialization.cpp
View File

@@ -12,6 +12,8 @@ struct ExpensiveToCopyType {
ExpensiveToCopyType();
virtual ~ExpensiveToCopyType();
const ExpensiveToCopyType &reference() const;
using ConstRef = const ExpensiveToCopyType &;
ConstRef referenceWithAlias() const;
const ExpensiveToCopyType *pointer() const;
Iterator<ExpensiveToCopyType> begin() const;
Iterator<ExpensiveToCopyType> end() const;
@@ -206,6 +208,15 @@ void positiveNonConstVarInCodeBlock(const ExpensiveToCopyType &Obj) {
}
}
void positiveNonConstVarInCodeBlockWithAlias(const ExpensiveToCopyType &Obj) {
{
const ExpensiveToCopyType Assigned = Obj.referenceWithAlias();
// CHECK-MESSAGES: [[@LINE-1]]:31: warning: the const qualified variable
// CHECK-FIXES: const ExpensiveToCopyType& Assigned = Obj.referenceWithAlias();
useAsConstReference(Assigned);
}
}
void negativeNonConstVarWithNonConstUse(const ExpensiveToCopyType &Obj) {
{
auto NonConstInvoked = Obj.reference();