[c++20] P0780R2: Support pack-expansion of init-captures.
This permits an init-capture to introduce a new pack:
template<typename ...T> auto x = [...a = T()] { /* a is a pack */ };
To support this, the mechanism for allowing ParmVarDecls to be packs has
been extended to support arbitrary local VarDecls.
llvm-svn: 361300
diff --git a/clang/lib/Sema/SemaLambda.cpp b/clang/lib/Sema/SemaLambda.cpp
index 1966e9e..b2055dd 100644
--- a/clang/lib/Sema/SemaLambda.cpp
+++ b/clang/lib/Sema/SemaLambda.cpp
@@ -753,11 +753,10 @@
}
}
-QualType Sema::buildLambdaInitCaptureInitialization(SourceLocation Loc,
- bool ByRef,
- IdentifierInfo *Id,
- bool IsDirectInit,
- Expr *&Init) {
+QualType Sema::buildLambdaInitCaptureInitialization(
+ SourceLocation Loc, bool ByRef, SourceLocation EllipsisLoc,
+ Optional<unsigned> NumExpansions, IdentifierInfo *Id, bool IsDirectInit,
+ Expr *&Init) {
// Create an 'auto' or 'auto&' TypeSourceInfo that we can use to
// deduce against.
QualType DeductType = Context.getAutoDeductType();
@@ -768,6 +767,18 @@
assert(!DeductType.isNull() && "can't build reference to auto");
TLB.push<ReferenceTypeLoc>(DeductType).setSigilLoc(Loc);
}
+ if (EllipsisLoc.isValid()) {
+ if (Init->containsUnexpandedParameterPack()) {
+ Diag(EllipsisLoc, getLangOpts().CPlusPlus2a
+ ? diag::warn_cxx17_compat_init_capture_pack
+ : diag::ext_init_capture_pack);
+ DeductType = Context.getPackExpansionType(DeductType, NumExpansions);
+ TLB.push<PackExpansionTypeLoc>(DeductType).setEllipsisLoc(EllipsisLoc);
+ } else {
+ // Just ignore the ellipsis for now and form a non-pack variable. We'll
+ // diagnose this later when we try to capture it.
+ }
+ }
TypeSourceInfo *TSI = TLB.getTypeSourceInfo(Context, DeductType);
// Deduce the type of the init capture.
@@ -808,10 +819,15 @@
VarDecl *Sema::createLambdaInitCaptureVarDecl(SourceLocation Loc,
QualType InitCaptureType,
+ SourceLocation EllipsisLoc,
IdentifierInfo *Id,
unsigned InitStyle, Expr *Init) {
- TypeSourceInfo *TSI = Context.getTrivialTypeSourceInfo(InitCaptureType,
- Loc);
+ // FIXME: Retain the TypeSourceInfo from buildLambdaInitCaptureInitialization
+ // rather than reconstructing it here.
+ TypeSourceInfo *TSI = Context.getTrivialTypeSourceInfo(InitCaptureType, Loc);
+ if (auto PETL = TSI->getTypeLoc().getAs<PackExpansionTypeLoc>())
+ PETL.setEllipsisLoc(EllipsisLoc);
+
// Create a dummy variable representing the init-capture. This is not actually
// used as a variable, and only exists as a way to name and refer to the
// init-capture.
@@ -1036,8 +1052,6 @@
? diag::warn_cxx11_compat_init_capture
: diag::ext_init_capture);
- if (C->Init.get()->containsUnexpandedParameterPack())
- ContainsUnexpandedParameterPack = true;
// If the initializer expression is usable, but the InitCaptureType
// is not, then an error has occurred - so ignore the capture for now.
// for e.g., [n{0}] { }; <-- if no <initializer_list> is included.
@@ -1046,6 +1060,10 @@
if (C->InitCaptureType.get().isNull())
continue;
+ if (C->Init.get()->containsUnexpandedParameterPack() &&
+ !C->InitCaptureType.get()->getAs<PackExpansionType>())
+ ContainsUnexpandedParameterPack = true;
+
unsigned InitStyle;
switch (C->InitKind) {
case LambdaCaptureInitKind::NoInit:
@@ -1061,7 +1079,8 @@
break;
}
Var = createLambdaInitCaptureVarDecl(C->Loc, C->InitCaptureType.get(),
- C->Id, InitStyle, C->Init.get());
+ C->EllipsisLoc, C->Id, InitStyle,
+ C->Init.get());
// C++1y [expr.prim.lambda]p11:
// An init-capture behaves as if it declares and explicitly
// captures a variable [...] whose declarative region is the
@@ -1153,7 +1172,8 @@
EllipsisLoc = C->EllipsisLoc;
} else {
Diag(C->EllipsisLoc, diag::err_pack_expansion_without_parameter_packs)
- << SourceRange(C->Loc);
+ << (C->Init.isUsable() ? C->Init.get()->getSourceRange()
+ : SourceRange(C->Loc));
// Just ignore the ellipsis.
}