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When instantiating the closure type of a lambda in a template, sometimes a
capture which is a pack is not expanded. When that happens, it is replaced with
a pack of size 1 containing that pack. Before it is replaced by another
instantiation where the pack is expanded, the size is reported to be 1 instead
of unknown.
This checks if this is happening (i.e., trying to replace a pack declaration
with a single declaration that is itself a pack), and not expanding it out in
that case.
Fixes https://github.com/llvm/llvm-project/issues/63677
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D154716
Files:
clang/lib/Sema/SemaTemplateInstantiate.cpp
clang/lib/Sema/TreeTransform.h
clang/test/SemaCXX/lambda-pack-expansion.cpp
Index: clang/test/SemaCXX/lambda-pack-expansion.cpp
===================================================================
--- clang/test/SemaCXX/lambda-pack-expansion.cpp
+++ clang/test/SemaCXX/lambda-pack-expansion.cpp
@@ -21,3 +21,18 @@
take_by_ref(x);
}
}
+
+namespace GH63677 {
+
+template<typename>
+void f() {
+ []<typename... Ts>() -> void {
+ [...us = Ts{}]{
+ (Ts(us), ...);
+ };
+ }.template operator()<int, int>();
+}
+
+template void f<int>();
+
+}
Index: clang/lib/Sema/TreeTransform.h
===================================================================
--- clang/lib/Sema/TreeTransform.h
+++ clang/lib/Sema/TreeTransform.h
@@ -13340,14 +13340,14 @@
OldVD->getInit()->getSourceRange(), Unexpanded, Expand,
RetainExpansion, NumExpansions))
return ExprError();
+ assert(!RetainExpansion && "Should not need to retain expansion after a "
+ "capture since it cannot be extended");
if (Expand) {
for (unsigned I = 0; I != *NumExpansions; ++I) {
Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), I);
SubstInitCapture(SourceLocation(), std::nullopt);
}
- }
- if (!Expand || RetainExpansion) {
- ForgetPartiallySubstitutedPackRAII Forget(getDerived());
+ } else {
SubstInitCapture(ExpansionTL.getEllipsisLoc(), NumExpansions);
Result.EllipsisLoc = ExpansionTL.getEllipsisLoc();
}
Index: clang/lib/Sema/SemaTemplateInstantiate.cpp
===================================================================
--- clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -1270,7 +1270,8 @@
}
void transformedLocalDecl(Decl *Old, ArrayRef<Decl *> NewDecls) {
- if (Old->isParameterPack()) {
+ if (Old->isParameterPack() &&
+ (NewDecls.size() != 1 || !NewDecls.front()->isParameterPack())) {
SemaRef.CurrentInstantiationScope->MakeInstantiatedLocalArgPack(Old);
for (auto *New : NewDecls)
SemaRef.CurrentInstantiationScope->InstantiatedLocalPackArg(
Index: clang/test/SemaCXX/lambda-pack-expansion.cpp
===================================================================
--- clang/test/SemaCXX/lambda-pack-expansion.cpp
+++ clang/test/SemaCXX/lambda-pack-expansion.cpp
@@ -21,3 +21,18 @@
take_by_ref(x);
}
}
+
+namespace GH63677 {
+
+template<typename>
+void f() {
+ []<typename... Ts>() -> void {
+ [...us = Ts{}]{
+ (Ts(us), ...);
+ };
+ }.template operator()<int, int>();
+}
+
+template void f<int>();
+
+}
Index: clang/lib/Sema/TreeTransform.h
===================================================================
--- clang/lib/Sema/TreeTransform.h
+++ clang/lib/Sema/TreeTransform.h
@@ -13340,14 +13340,14 @@
OldVD->getInit()->getSourceRange(), Unexpanded, Expand,
RetainExpansion, NumExpansions))
return ExprError();
+ assert(!RetainExpansion && "Should not need to retain expansion after a "
+ "capture since it cannot be extended");
if (Expand) {
for (unsigned I = 0; I != *NumExpansions; ++I) {
Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), I);
SubstInitCapture(SourceLocation(), std::nullopt);
}
- }
- if (!Expand || RetainExpansion) {
- ForgetPartiallySubstitutedPackRAII Forget(getDerived());
+ } else {
SubstInitCapture(ExpansionTL.getEllipsisLoc(), NumExpansions);
Result.EllipsisLoc = ExpansionTL.getEllipsisLoc();
}
Index: clang/lib/Sema/SemaTemplateInstantiate.cpp
===================================================================
--- clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -1270,7 +1270,8 @@
}
void transformedLocalDecl(Decl *Old, ArrayRef<Decl *> NewDecls) {
- if (Old->isParameterPack()) {
+ if (Old->isParameterPack() &&
+ (NewDecls.size() != 1 || !NewDecls.front()->isParameterPack())) {
SemaRef.CurrentInstantiationScope->MakeInstantiatedLocalArgPack(Old);
for (auto *New : NewDecls)
SemaRef.CurrentInstantiationScope->InstantiatedLocalPackArg(
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