rsmith accepted this revision.
rsmith added a comment.
Thanks, I think this makes sense as a generalization of the existing "idiomatic
aggregate initialization" rule. Some suggested cleanups but otherwise LGTM.
================
Comment at: clang/lib/Sema/SemaInit.cpp:1001
/// the braces in aggregate initialization.
static bool isIdiomaticBraceElisionEntity(const InitializedEntity &Entity) {
// Recursive initialization of the one and only field within an aggregate
----------------
I wonder if it'd be clearer to replace the one base and no fields check and the
one field and no bases check with something like:
```
// Brace elision is idiomatic if we're initializing the only direct subobject
of
// an aggregate of record type.
if (Entity.getKind() == InitializedEntity::EK_Base ||
Entity.getKind() == InitializedEntity::EK_Member) {
auto *ParentRD = Entity.getParent()->getType()->getAsRecordDecl();
unsigned Subobjects = std::distance(ParentRD->field_begin(),
ParentRD->field_end());
if (auto *CXXRD = dyn_cast<CXXRecordDecl>(ParentRD))
Subobjects += CXXRD->getNumBases();
return Subobjects == 1;
}
```
This'd be linear in the number of fields instead of constant-time, but I
suspect that doesn't matter in practice. Aggregate initialization is linear in
the number of fields regardless.
(No strong preference here; take this or leave it.)
================
Comment at: clang/lib/Sema/SemaInit.cpp:1017-1021
+ if (CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(ParentRD)) {
+ if (CXXRD->getNumBases() == 1) {
+ return ParentRD->field_begin() == ParentRD->field_end();
+ }
+ }
----------------
Some minor simplifications. (We can `cast` rather than `dyn_cast`ing here
because we're initializing a base class, so the parent *must* be a C++ class
type.)
================
Comment at: clang/lib/Sema/SemaInit.cpp:1025
- auto FieldIt = ParentRD->field_begin();
- assert(FieldIt != ParentRD->field_end() &&
- "no fields but have initializer for member?");
- return ++FieldIt == ParentRD->field_end();
+ // Allows elide brace initialization for aggregates with one member.
+ if (Entity.getKind() == InitializedEntity::EK_Member) {
----------------
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D100057/new/
https://reviews.llvm.org/D100057
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