benhamilton created this revision.
benhamilton added reviewers: alexfh, hokein.
Herald added subscribers: cfe-commits, xazax.hun, klimek.
The following Objective-C code currently incorrectly triggers
clang-tidy's performance-unnecessary-value-param check:
% cat /tmp/performance-unnecessary-value-param-arc.m
void foo(id object) { }
clang-tidy /tmp/performance-unnecessary-value-param-arc.m
-checks=-\*,performance-unnecessary-value-param -- -xobjective-c
-fobjc-abi-version=2 -fobjc-arc
1 warning generated.
/src/llvm/tools/clang/tools/extra/test/clang-tidy/performance-unnecessary-value-param-arc.m:10:13:
warning: the parameter 'object' is copied for each invocation but only
used as a const reference; consider making it a const reference
[performance-unnecessary-value-param]
void foo(id object) { }
~~ ^
const &
This is wrong for a few reasons:
1. Objective-C doesn't have references, so `const &` is not going to help
2. ARC heavily optimizes the "expensive" copy which triggers the warning
This fixes the issue by disabling the warning for non-C++, as well as
disabling it for objects under ARC memory management for
Objective-C++.
Test Plan: New tests added. Ran tests with `make -j12 check-clang-tools`.
Repository:
rCTE Clang Tools Extra
https://reviews.llvm.org/D42812
Files:
clang-tidy/performance/UnnecessaryValueParamCheck.cpp
clang-tidy/utils/TypeTraits.cpp
test/clang-tidy/performance-unnecessary-value-param-arc.m
test/clang-tidy/performance-unnecessary-value-param-arc.mm
Index: test/clang-tidy/performance-unnecessary-value-param-arc.mm
===================================================================
--- /dev/null
+++ test/clang-tidy/performance-unnecessary-value-param-arc.mm
@@ -0,0 +1,16 @@
+// RUN: clang-tidy %s -checks=-*,performance-unnecessary-value-param -- \
+// RUN: -xobjective-c++ -fobjc-abi-version=2 -fobjc-arc | count 0
+
+#if !__has_feature(objc_arc)
+#error Objective-C ARC not enabled as expected
+#endif
+
+// Passing an Objective-C ARC-managed object to a C function should
+// not raise performance-unnecessary-value-param.
+void foo(id object) { }
+
+// Same for explcitly non-ARC-managed Objective-C objects.
+void bar(__unsafe_unretained id object) { }
+
+// Same for Objective-c classes.
+void baz(Class c) { }
Index: test/clang-tidy/performance-unnecessary-value-param-arc.m
===================================================================
--- /dev/null
+++ test/clang-tidy/performance-unnecessary-value-param-arc.m
@@ -0,0 +1,16 @@
+// RUN: clang-tidy %s -checks=-*,performance-unnecessary-value-param -- \
+// RUN: -xobjective-c -fobjc-abi-version=2 -fobjc-arc | count 0
+
+#if !__has_feature(objc_arc)
+#error Objective-C ARC not enabled as expected
+#endif
+
+// Passing an Objective-C ARC-managed object to a C function should
+// not raise performance-unnecessary-value-param.
+void foo(id object) { }
+
+// Same for explcitly non-ARC-managed Objective-C objects.
+void bar(__unsafe_unretained id object) { }
+
+// Same for Objective-c classes.
+void baz(Class c) { }
Index: clang-tidy/utils/TypeTraits.cpp
===================================================================
--- clang-tidy/utils/TypeTraits.cpp
+++ clang-tidy/utils/TypeTraits.cpp
@@ -45,7 +45,8 @@
return llvm::None;
return !Type.isTriviallyCopyableType(Context) &&
!classHasTrivialCopyAndDestroy(Type) &&
- !hasDeletedCopyConstructor(Type);
+ !hasDeletedCopyConstructor(Type) &&
+ !Type->isObjCLifetimeType();
}
bool recordIsTriviallyDefaultConstructible(const RecordDecl &RecordDecl,
Index: clang-tidy/performance/UnnecessaryValueParamCheck.cpp
===================================================================
--- clang-tidy/performance/UnnecessaryValueParamCheck.cpp
+++ clang-tidy/performance/UnnecessaryValueParamCheck.cpp
@@ -79,6 +79,10 @@
Options.getLocalOrGlobal("IncludeStyle", "llvm"))) {}
void UnnecessaryValueParamCheck::registerMatchers(MatchFinder *Finder) {
+ // This check is specific to C++ and doesn't apply to languages like
+ // Objective-C.
+ if (!getLangOpts().CPlusPlus)
+ return;
const auto ExpensiveValueParamDecl =
parmVarDecl(hasType(hasCanonicalType(allOf(
unless(referenceType()),
matchers::isExpensiveToCopy()))),
Index: test/clang-tidy/performance-unnecessary-value-param-arc.mm
===================================================================
--- /dev/null
+++ test/clang-tidy/performance-unnecessary-value-param-arc.mm
@@ -0,0 +1,16 @@
+// RUN: clang-tidy %s -checks=-*,performance-unnecessary-value-param -- \
+// RUN: -xobjective-c++ -fobjc-abi-version=2 -fobjc-arc | count 0
+
+#if !__has_feature(objc_arc)
+#error Objective-C ARC not enabled as expected
+#endif
+
+// Passing an Objective-C ARC-managed object to a C function should
+// not raise performance-unnecessary-value-param.
+void foo(id object) { }
+
+// Same for explcitly non-ARC-managed Objective-C objects.
+void bar(__unsafe_unretained id object) { }
+
+// Same for Objective-c classes.
+void baz(Class c) { }
Index: test/clang-tidy/performance-unnecessary-value-param-arc.m
===================================================================
--- /dev/null
+++ test/clang-tidy/performance-unnecessary-value-param-arc.m
@@ -0,0 +1,16 @@
+// RUN: clang-tidy %s -checks=-*,performance-unnecessary-value-param -- \
+// RUN: -xobjective-c -fobjc-abi-version=2 -fobjc-arc | count 0
+
+#if !__has_feature(objc_arc)
+#error Objective-C ARC not enabled as expected
+#endif
+
+// Passing an Objective-C ARC-managed object to a C function should
+// not raise performance-unnecessary-value-param.
+void foo(id object) { }
+
+// Same for explcitly non-ARC-managed Objective-C objects.
+void bar(__unsafe_unretained id object) { }
+
+// Same for Objective-c classes.
+void baz(Class c) { }
Index: clang-tidy/utils/TypeTraits.cpp
===================================================================
--- clang-tidy/utils/TypeTraits.cpp
+++ clang-tidy/utils/TypeTraits.cpp
@@ -45,7 +45,8 @@
return llvm::None;
return !Type.isTriviallyCopyableType(Context) &&
!classHasTrivialCopyAndDestroy(Type) &&
- !hasDeletedCopyConstructor(Type);
+ !hasDeletedCopyConstructor(Type) &&
+ !Type->isObjCLifetimeType();
}
bool recordIsTriviallyDefaultConstructible(const RecordDecl &RecordDecl,
Index: clang-tidy/performance/UnnecessaryValueParamCheck.cpp
===================================================================
--- clang-tidy/performance/UnnecessaryValueParamCheck.cpp
+++ clang-tidy/performance/UnnecessaryValueParamCheck.cpp
@@ -79,6 +79,10 @@
Options.getLocalOrGlobal("IncludeStyle", "llvm"))) {}
void UnnecessaryValueParamCheck::registerMatchers(MatchFinder *Finder) {
+ // This check is specific to C++ and doesn't apply to languages like
+ // Objective-C.
+ if (!getLangOpts().CPlusPlus)
+ return;
const auto ExpensiveValueParamDecl =
parmVarDecl(hasType(hasCanonicalType(allOf(
unless(referenceType()), matchers::isExpensiveToCopy()))),
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