[clang] Changed Checks from TriviallyCopyable to TriviallyCopyConstructible (PR #76680)
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Mon Jan 1 06:38:48 PST 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang
Author: Bhuminjay Soni (11happy)
<details>
<summary>Changes</summary>
**Overview:**
This pull request fixes #<!-- -->47355 where in the Clang compiler's range-loop-analysis incorrectly checks for trivial copyability instead of trivial copy constructibility, leading to erroneous warnings.
**Changes Made:**
- The changes made in this commit address the issue by introducing a new member function `isTriviallyCopyConstructible` in the `CXXRecordDecl` class and implementing it in the associated files `(clang/include/clang/AST/DeclCXX.h, clang/lib/AST/DeclCXX.cpp)`. Additionally, modifications are made in `clang/include/clang/AST/Type.h` and `clang/lib/AST/Type.cpp` to support the new function. The implementation checks for trivial copy constructibility, distinguishing it from the existing `isTriviallyCopyable` check. The issue in `clang/lib/Sema/SemaStmt.cpp` is also addressed by updating the conditional check in the `DiagnoseForRangeConstVariableCopies` function to use the new `isTriviallyCopyConstructibleType` function. Overall, these changes aim to correct the range-loop-analysis by ensuring it checks for trivial copy constructibility rather than trivial copyability.
**Testing:**
- Tested the updated code.
- Verified that other functionalities remain unaffected.
**Dependencies:**
- No dependencies on other pull requests.
**References:**
- https://cplusplus.com/reference/type_traits/is_trivially_copy_constructible/
- https://en.cppreference.com/w/cpp/named_req/CopyConstructible
- https://cplusplus.com/reference/type_traits/is_trivially_copyable/
**CC:**
- @<!-- -->Endilll , @<!-- -->r4nt , @<!-- -->AaronBallman
---
Full diff: https://github.com/llvm/llvm-project/pull/76680.diff
5 Files Affected:
- (modified) clang/include/clang/AST/DeclCXX.h (+3)
- (modified) clang/include/clang/AST/Type.h (+3)
- (modified) clang/lib/AST/DeclCXX.cpp (+13)
- (modified) clang/lib/AST/Type.cpp (+43)
- (modified) clang/lib/Sema/SemaStmt.cpp (+1-1)
``````````diff
diff --git a/clang/include/clang/AST/DeclCXX.h b/clang/include/clang/AST/DeclCXX.h
index 432293583576b5..3ac0d6a9e083cd 100644
--- a/clang/include/clang/AST/DeclCXX.h
+++ b/clang/include/clang/AST/DeclCXX.h
@@ -1425,6 +1425,9 @@ class CXXRecordDecl : public RecordDecl {
/// (C++11 [class]p6).
bool isTriviallyCopyable() const;
+ /// Determine whether this class is considered trivially copyable per
+ bool isTriviallyCopyConstructible() const;
+
/// Determine whether this class is considered trivial.
///
/// C++11 [class]p6:
diff --git a/clang/include/clang/AST/Type.h b/clang/include/clang/AST/Type.h
index 1afa693672860f..bce2256f96a828 100644
--- a/clang/include/clang/AST/Type.h
+++ b/clang/include/clang/AST/Type.h
@@ -917,6 +917,9 @@ class QualType {
/// Return true if this is a trivially copyable type (C++0x [basic.types]p9)
bool isTriviallyCopyableType(const ASTContext &Context) const;
+ /// Return true if this is a trivially copyable type
+ bool isTriviallyCopyConstructibleType(const ASTContext &Context) const;
+
/// Return true if this is a trivially relocatable type.
bool isTriviallyRelocatableType(const ASTContext &Context) const;
diff --git a/clang/lib/AST/DeclCXX.cpp b/clang/lib/AST/DeclCXX.cpp
index c944862fcefeee..98b0a6dc28ea2f 100644
--- a/clang/lib/AST/DeclCXX.cpp
+++ b/clang/lib/AST/DeclCXX.cpp
@@ -587,6 +587,19 @@ bool CXXRecordDecl::isTriviallyCopyable() const {
return true;
}
+bool CXXRecordDecl::isTriviallyCopyConstructible() const {
+
+ // A trivially copy constructible class is a class that:
+ // -- has no non-trivial copy constructors,
+ if (hasNonTrivialCopyConstructor())
+ return false;
+ // -- has a trivial destructor.
+ if (!hasTrivialDestructor())
+ return false;
+
+ return true;
+}
+
void CXXRecordDecl::markedVirtualFunctionPure() {
// C++ [class.abstract]p2:
// A class is abstract if it has at least one pure virtual function.
diff --git a/clang/lib/AST/Type.cpp b/clang/lib/AST/Type.cpp
index 160a725939ccd4..9c8b25798a0a95 100644
--- a/clang/lib/AST/Type.cpp
+++ b/clang/lib/AST/Type.cpp
@@ -2644,6 +2644,49 @@ bool QualType::isTriviallyCopyableType(const ASTContext &Context) const {
return false;
}
+bool QualType::isTriviallyCopyConstructibleType(
+ const ASTContext &Context) const {
+ if ((*this)->isArrayType())
+ return Context.getBaseElementType(*this).isTriviallyCopyConstructibleType(
+ Context);
+
+ if (hasNonTrivialObjCLifetime())
+ return false;
+
+ // C++11 [basic.types]p9 - See Core 2094
+ // Scalar types, trivially copyable class types, arrays of such types, and
+ // cv-qualified versions of these types are collectively
+ // called trivially copy constructible types.
+
+ QualType CanonicalType = getCanonicalType();
+ if (CanonicalType->isDependentType())
+ return false;
+
+ if (CanonicalType->isSizelessBuiltinType())
+ return true;
+
+ // Return false for incomplete types after skipping any incomplete array types
+ // which are expressly allowed by the standard and thus our API.
+ if (CanonicalType->isIncompleteType())
+ return false;
+
+ // As an extension, Clang treats vector types as Scalar types.
+ if (CanonicalType->isScalarType() || CanonicalType->isVectorType())
+ return true;
+
+ if (const auto *RT = CanonicalType->getAs<RecordType>()) {
+ if (const auto *ClassDecl = dyn_cast<CXXRecordDecl>(RT->getDecl())) {
+ if (!ClassDecl->isTriviallyCopyConstructible())
+ return false;
+ }
+
+ return true;
+ }
+
+ // No other types can match.
+ return false;
+}
+
bool QualType::isTriviallyRelocatableType(const ASTContext &Context) const {
QualType BaseElementType = Context.getBaseElementType(*this);
diff --git a/clang/lib/Sema/SemaStmt.cpp b/clang/lib/Sema/SemaStmt.cpp
index f0b03db690843a..21efe25ed84a3d 100644
--- a/clang/lib/Sema/SemaStmt.cpp
+++ b/clang/lib/Sema/SemaStmt.cpp
@@ -3200,7 +3200,7 @@ static void DiagnoseForRangeConstVariableCopies(Sema &SemaRef,
// (The function `getTypeSize` returns the size in bits.)
ASTContext &Ctx = SemaRef.Context;
if (Ctx.getTypeSize(VariableType) <= 64 * 8 &&
- (VariableType.isTriviallyCopyableType(Ctx) ||
+ (VariableType.isTriviallyCopyConstructibleType(Ctx) ||
hasTrivialABIAttr(VariableType)))
return;
``````````
</details>
https://github.com/llvm/llvm-project/pull/76680
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