flx created this revision.
flx added reviewers: hokein, ymandel, aaron.ballman.
Herald added subscribers: jeroen.dobbelaere, xazax.hun.
flx requested review of this revision.
Herald added a project: clang-tools-extra.
Herald added a subscriber: cfe-commits.
This fixes a false positive case where for instance a pointer is obtained and
declared using `auto`.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D103018
Files:
clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
clang-tools-extra/test/clang-tidy/checkers/performance-unnecessary-copy-initialization.cpp
Index:
clang-tools-extra/test/clang-tidy/checkers/performance-unnecessary-copy-initialization.cpp
===================================================================
---
clang-tools-extra/test/clang-tidy/checkers/performance-unnecessary-copy-initialization.cpp
+++
clang-tools-extra/test/clang-tidy/checkers/performance-unnecessary-copy-initialization.cpp
@@ -4,6 +4,7 @@
ExpensiveToCopyType();
virtual ~ExpensiveToCopyType();
const ExpensiveToCopyType &reference() const;
+ const ExpensiveToCopyType *pointer() const;
void nonConstMethod();
bool constMethod() const;
};
@@ -500,6 +501,25 @@
Orig.nonConstMethod();
}
+void negativeAliasNonCanonicalPointerType() {
+ ExpensiveToCopyType Orig;
+ // The use of auto here hides that the type is a pointer type. The check
needs
+ // to look at the canonical type to detect the aliasing through this pointer.
+ const auto Pointer = Orig.pointer();
+ const auto NecessaryCopy = Pointer->reference();
+ Orig.nonConstMethod();
+}
+
+void negativeAliasTypedefedType() {
+ typedef const ExpensiveToCopyType &ReferenceType;
+ ExpensiveToCopyType Orig;
+ // The typedef hides the fact that this is a reference type. The check needs
+ // to look at the canonical type to detect the aliasing.
+ ReferenceType Ref = Orig.reference();
+ const auto NecessaryCopy = Ref.reference();
+ Orig.nonConstMethod();
+}
+
void positiveCopiedFromGetterOfReferenceToConstVar() {
ExpensiveToCopyType Orig;
const auto &Ref = Orig.reference();
Index:
clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
===================================================================
--- clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
+++ clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
@@ -86,7 +86,7 @@
if (!isOnlyUsedAsConst(InitializingVar, BlockStmt, Context))
return false;
- QualType T = InitializingVar.getType();
+ QualType T = InitializingVar.getType().getCanonicalType();
// The variable is a value type and we know it is only used as const. Safe
// to reference it and avoid the copy.
if (!isa<ReferenceType, PointerType>(T))
Index: clang-tools-extra/test/clang-tidy/checkers/performance-unnecessary-copy-initialization.cpp
===================================================================
--- clang-tools-extra/test/clang-tidy/checkers/performance-unnecessary-copy-initialization.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/performance-unnecessary-copy-initialization.cpp
@@ -4,6 +4,7 @@
ExpensiveToCopyType();
virtual ~ExpensiveToCopyType();
const ExpensiveToCopyType &reference() const;
+ const ExpensiveToCopyType *pointer() const;
void nonConstMethod();
bool constMethod() const;
};
@@ -500,6 +501,25 @@
Orig.nonConstMethod();
}
+void negativeAliasNonCanonicalPointerType() {
+ ExpensiveToCopyType Orig;
+ // The use of auto here hides that the type is a pointer type. The check needs
+ // to look at the canonical type to detect the aliasing through this pointer.
+ const auto Pointer = Orig.pointer();
+ const auto NecessaryCopy = Pointer->reference();
+ Orig.nonConstMethod();
+}
+
+void negativeAliasTypedefedType() {
+ typedef const ExpensiveToCopyType &ReferenceType;
+ ExpensiveToCopyType Orig;
+ // The typedef hides the fact that this is a reference type. The check needs
+ // to look at the canonical type to detect the aliasing.
+ ReferenceType Ref = Orig.reference();
+ const auto NecessaryCopy = Ref.reference();
+ Orig.nonConstMethod();
+}
+
void positiveCopiedFromGetterOfReferenceToConstVar() {
ExpensiveToCopyType Orig;
const auto &Ref = Orig.reference();
Index: clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
===================================================================
--- clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
+++ clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
@@ -86,7 +86,7 @@
if (!isOnlyUsedAsConst(InitializingVar, BlockStmt, Context))
return false;
- QualType T = InitializingVar.getType();
+ QualType T = InitializingVar.getType().getCanonicalType();
// The variable is a value type and we know it is only used as const. Safe
// to reference it and avoid the copy.
if (!isa<ReferenceType, PointerType>(T))
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