[Sema] Diagnose default-initialization, destruction, and copying of
non-trivial C union types
This recommits r365985, which was reverted because it broke a few
projects using unions containing non-trivial ObjC pointer fields in
system headers. We now have a patch to fix the problem (see
https://reviews.llvm.org/D65256).
Original commit message:
This patch diagnoses uses of non-trivial C unions and structs/unions
containing non-trivial C unions in the following contexts, which require
default-initialization, destruction, or copying of the union objects,
instead of disallowing fields of non-trivial types in C unions, which is
what we currently do:
- function parameters.
- function returns.
- assignments.
- compound literals.
- block captures except capturing of `__block` variables by non-escaping blocks.
- local and global variable definitions.
- lvalue-to-rvalue conversions of volatile types.
See the discussion in https://reviews.llvm.org/D62988 for more background.
rdar://problem/50679094
Differential Revision: https://reviews.llvm.org/D63753
llvm-svn: 371275
diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
index 152cc7d..3f4dacb 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -1684,12 +1684,24 @@
// Set the EscapingByref flag of __block variables captured by
// escaping blocks.
for (const BlockDecl *BD : FSI.Blocks) {
- if (BD->doesNotEscape())
- continue;
for (const BlockDecl::Capture &BC : BD->captures()) {
VarDecl *VD = BC.getVariable();
- if (VD->hasAttr<BlocksAttr>())
+ if (VD->hasAttr<BlocksAttr>()) {
+ // Nothing to do if this is a __block variable captured by a
+ // non-escaping block.
+ if (BD->doesNotEscape())
+ continue;
VD->setEscapingByref();
+ }
+ // Check whether the captured variable is or contains an object of
+ // non-trivial C union type.
+ QualType CapType = BC.getVariable()->getType();
+ if (CapType.hasNonTrivialToPrimitiveDestructCUnion() ||
+ CapType.hasNonTrivialToPrimitiveCopyCUnion())
+ S.checkNonTrivialCUnion(BC.getVariable()->getType(),
+ BD->getCaretLocation(),
+ Sema::NTCUC_BlockCapture,
+ Sema::NTCUK_Destruct|Sema::NTCUK_Copy);
}
}