[clang] [clang][NFC] Add missing placement-new after Allocate() calls (PR #68382)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

<details>
<summary>Changes</summary>

While working on #<!-- -->68377 inspecting `Allocate()` calls, I found out that there are couple of places where we forget to use placement-new to create objects in the allocated memory.

---
Full diff: https://github.com/llvm/llvm-project/pull/68382.diff


3 Files Affected:

- (modified) clang/lib/AST/DeclCXX.cpp (+2-1) 
- (modified) clang/lib/AST/DeclObjC.cpp (+2-2) 
- (modified) clang/lib/Serialization/ASTReaderDecl.cpp (+5-2) 


``````````diff
diff --git a/clang/lib/AST/DeclCXX.cpp b/clang/lib/AST/DeclCXX.cpp
index 42bab4ed51b7290..a92b788366434ce 100644
--- a/clang/lib/AST/DeclCXX.cpp
+++ b/clang/lib/AST/DeclCXX.cpp
@@ -1484,7 +1484,8 @@ void CXXRecordDecl::setCaptures(ASTContext &Context,
     if (Captures[I].isExplicit())
       ++Data.NumExplicitCaptures;
 
-    *ToCapture++ = Captures[I];
+    new (ToCapture) LambdaCapture(Captures[I]);
+    ToCapture++;
   }
 
   if (!lambdaIsDefaultConstructibleAndAssignable())
diff --git a/clang/lib/AST/DeclObjC.cpp b/clang/lib/AST/DeclObjC.cpp
index e934a81d086e3c0..e1eef2dbd9c3d28 100644
--- a/clang/lib/AST/DeclObjC.cpp
+++ b/clang/lib/AST/DeclObjC.cpp
@@ -931,8 +931,8 @@ void ObjCMethodDecl::setParamsAndSelLocs(ASTContext &C,
   unsigned Size = sizeof(ParmVarDecl *) * NumParams +
                   sizeof(SourceLocation) * SelLocs.size();
   ParamsAndSelLocs = C.Allocate(Size);
-  std::copy(Params.begin(), Params.end(), getParams());
-  std::copy(SelLocs.begin(), SelLocs.end(), getStoredSelLocs());
+  std::uninitialized_copy(Params.begin(), Params.end(), getParams());
+  std::uninitialized_copy(SelLocs.begin(), SelLocs.end(), getStoredSelLocs());
 }
 
 void ObjCMethodDecl::getSelectorLocs(
diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index d553b3c6d78dedc..6a2f607d916c472 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -2002,13 +2002,16 @@ void ASTDeclReader::ReadCXXDefinitionData(
       case LCK_StarThis:
       case LCK_This:
       case LCK_VLAType:
-        *ToCapture++ = Capture(Loc, IsImplicit, Kind, nullptr,SourceLocation());
+        new (ToCapture)
+            Capture(Loc, IsImplicit, Kind, nullptr, SourceLocation());
+        ToCapture++;
         break;
       case LCK_ByCopy:
       case LCK_ByRef:
         auto *Var = readDeclAs<VarDecl>();
         SourceLocation EllipsisLoc = readSourceLocation();
-        *ToCapture++ = Capture(Loc, IsImplicit, Kind, Var, EllipsisLoc);
+        new (ToCapture) Capture(Loc, IsImplicit, Kind, Var, EllipsisLoc);
+        ToCapture++;
         break;
       }
     }

``````````

</details>


https://github.com/llvm/llvm-project/pull/68382