PR12057: Allow variadic template pack expansions to cross lambda boundaries.
Rather than adding a ContainsUnexpandedParameterPack bit to essentially every
AST node, we tunnel the bit directly up to the surrounding lambda expression
when we reach a context where an unexpanded pack can not normally appear.
Thus any statement or declaration within a lambda can now potentially contain
an unexpanded parameter pack.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@160705 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaTemplateVariadic.cpp b/lib/Sema/SemaTemplateVariadic.cpp
index 0d0f992..aece90b 100644
--- a/lib/Sema/SemaTemplateVariadic.cpp
+++ b/lib/Sema/SemaTemplateVariadic.cpp
@@ -12,6 +12,7 @@
#include "clang/Sema/Sema.h"
#include "clang/Sema/Lookup.h"
#include "clang/Sema/ParsedTemplate.h"
+#include "clang/Sema/ScopeInfo.h"
#include "clang/Sema/SemaInternal.h"
#include "clang/Sema/Template.h"
#include "clang/AST/Expr.h"
@@ -34,10 +35,12 @@
SmallVectorImpl<UnexpandedParameterPack> &Unexpanded;
+ bool InLambda;
+
public:
explicit CollectUnexpandedParameterPacksVisitor(
SmallVectorImpl<UnexpandedParameterPack> &Unexpanded)
- : Unexpanded(Unexpanded) { }
+ : Unexpanded(Unexpanded), InLambda(false) { }
bool shouldWalkTypesOfTypeLocs() const { return false; }
@@ -107,17 +110,17 @@
/// \brief Suppress traversal into statements and expressions that
/// do not contain unexpanded parameter packs.
bool TraverseStmt(Stmt *S) {
- if (Expr *E = dyn_cast_or_null<Expr>(S))
- if (E->containsUnexpandedParameterPack())
- return inherited::TraverseStmt(E);
+ Expr *E = dyn_cast_or_null<Expr>(S);
+ if ((E && E->containsUnexpandedParameterPack()) || InLambda)
+ return inherited::TraverseStmt(S);
- return true;
+ return true;
}
/// \brief Suppress traversal into types that do not contain
/// unexpanded parameter packs.
bool TraverseType(QualType T) {
- if (!T.isNull() && T->containsUnexpandedParameterPack())
+ if ((!T.isNull() && T->containsUnexpandedParameterPack()) || InLambda)
return inherited::TraverseType(T);
return true;
@@ -126,8 +129,9 @@
/// \brief Suppress traversel into types with location information
/// that do not contain unexpanded parameter packs.
bool TraverseTypeLoc(TypeLoc TL) {
- if (!TL.getType().isNull() &&
- TL.getType()->containsUnexpandedParameterPack())
+ if ((!TL.getType().isNull() &&
+ TL.getType()->containsUnexpandedParameterPack()) ||
+ InLambda)
return inherited::TraverseTypeLoc(TL);
return true;
@@ -136,10 +140,10 @@
/// \brief Suppress traversal of non-parameter declarations, since
/// they cannot contain unexpanded parameter packs.
bool TraverseDecl(Decl *D) {
- if (D && isa<ParmVarDecl>(D))
+ if ((D && isa<ParmVarDecl>(D)) || InLambda)
return inherited::TraverseDecl(D);
- return true;
+ return true;
}
/// \brief Suppress traversal of template argument pack expansions.
@@ -157,17 +161,57 @@
return inherited::TraverseTemplateArgumentLoc(ArgLoc);
}
+
+ /// \brief Note whether we're traversing a lambda containing an unexpanded
+ /// parameter pack. In this case, the unexpanded pack can occur anywhere,
+ /// including all the places where we normally wouldn't look. Within a
+ /// lambda, we don't propagate the 'contains unexpanded parameter pack' bit
+ /// outside an expression.
+ bool TraverseLambdaExpr(LambdaExpr *Lambda) {
+ // The ContainsUnexpandedParameterPack bit on a lambda is always correct,
+ // even if it's contained within another lambda.
+ if (!Lambda->containsUnexpandedParameterPack())
+ return true;
+
+ bool WasInLambda = InLambda;
+ InLambda = true;
+
+ // If any capture names a function parameter pack, that pack is expanded
+ // when the lambda is expanded.
+ for (LambdaExpr::capture_iterator I = Lambda->capture_begin(),
+ E = Lambda->capture_end(); I != E; ++I)
+ if (VarDecl *VD = I->getCapturedVar())
+ if (VD->isParameterPack())
+ Unexpanded.push_back(std::make_pair(VD, I->getLocation()));
+
+ inherited::TraverseLambdaExpr(Lambda);
+
+ InLambda = WasInLambda;
+ return true;
+ }
};
}
/// \brief Diagnose all of the unexpanded parameter packs in the given
/// vector.
-void
+bool
Sema::DiagnoseUnexpandedParameterPacks(SourceLocation Loc,
UnexpandedParameterPackContext UPPC,
ArrayRef<UnexpandedParameterPack> Unexpanded) {
if (Unexpanded.empty())
- return;
+ return false;
+
+ // If we are within a lambda expression, that lambda contains an unexpanded
+ // parameter pack, and we are done.
+ // FIXME: Store 'Unexpanded' on the lambda so we don't need to recompute it
+ // later.
+ for (unsigned N = FunctionScopes.size(); N; --N) {
+ if (sema::LambdaScopeInfo *LSI =
+ dyn_cast<sema::LambdaScopeInfo>(FunctionScopes[N-1])) {
+ LSI->ContainsUnexpandedParameterPack = true;
+ return false;
+ }
+ }
SmallVector<SourceLocation, 4> Locations;
SmallVector<IdentifierInfo *, 4> Names;
@@ -200,6 +244,7 @@
for (unsigned I = 0, N = Locations.size(); I != N; ++I)
DB << SourceRange(Locations[I]);
+ return true;
}
bool Sema::DiagnoseUnexpandedParameterPack(SourceLocation Loc,
@@ -215,8 +260,7 @@
CollectUnexpandedParameterPacksVisitor(Unexpanded).TraverseTypeLoc(
T->getTypeLoc());
assert(!Unexpanded.empty() && "Unable to find unexpanded parameter packs");
- DiagnoseUnexpandedParameterPacks(Loc, UPPC, Unexpanded);
- return true;
+ return DiagnoseUnexpandedParameterPacks(Loc, UPPC, Unexpanded);
}
bool Sema::DiagnoseUnexpandedParameterPack(Expr *E,
@@ -230,8 +274,7 @@
SmallVector<UnexpandedParameterPack, 2> Unexpanded;
CollectUnexpandedParameterPacksVisitor(Unexpanded).TraverseStmt(E);
assert(!Unexpanded.empty() && "Unable to find unexpanded parameter packs");
- DiagnoseUnexpandedParameterPacks(E->getLocStart(), UPPC, Unexpanded);
- return true;
+ return DiagnoseUnexpandedParameterPacks(E->getLocStart(), UPPC, Unexpanded);
}
bool Sema::DiagnoseUnexpandedParameterPack(const CXXScopeSpec &SS,
@@ -247,9 +290,8 @@
CollectUnexpandedParameterPacksVisitor(Unexpanded)
.TraverseNestedNameSpecifier(SS.getScopeRep());
assert(!Unexpanded.empty() && "Unable to find unexpanded parameter packs");
- DiagnoseUnexpandedParameterPacks(SS.getRange().getBegin(),
- UPPC, Unexpanded);
- return true;
+ return DiagnoseUnexpandedParameterPacks(SS.getRange().getBegin(),
+ UPPC, Unexpanded);
}
bool Sema::DiagnoseUnexpandedParameterPack(const DeclarationNameInfo &NameInfo,
@@ -284,8 +326,7 @@
CollectUnexpandedParameterPacksVisitor(Unexpanded)
.TraverseType(NameInfo.getName().getCXXNameType());
assert(!Unexpanded.empty() && "Unable to find unexpanded parameter packs");
- DiagnoseUnexpandedParameterPacks(NameInfo.getLoc(), UPPC, Unexpanded);
- return true;
+ return DiagnoseUnexpandedParameterPacks(NameInfo.getLoc(), UPPC, Unexpanded);
}
bool Sema::DiagnoseUnexpandedParameterPack(SourceLocation Loc,
@@ -299,8 +340,7 @@
CollectUnexpandedParameterPacksVisitor(Unexpanded)
.TraverseTemplateName(Template);
assert(!Unexpanded.empty() && "Unable to find unexpanded parameter packs");
- DiagnoseUnexpandedParameterPacks(Loc, UPPC, Unexpanded);
- return true;
+ return DiagnoseUnexpandedParameterPacks(Loc, UPPC, Unexpanded);
}
bool Sema::DiagnoseUnexpandedParameterPack(TemplateArgumentLoc Arg,
@@ -313,8 +353,7 @@
CollectUnexpandedParameterPacksVisitor(Unexpanded)
.TraverseTemplateArgumentLoc(Arg);
assert(!Unexpanded.empty() && "Unable to find unexpanded parameter packs");
- DiagnoseUnexpandedParameterPacks(Arg.getLocation(), UPPC, Unexpanded);
- return true;
+ return DiagnoseUnexpandedParameterPacks(Arg.getLocation(), UPPC, Unexpanded);
}
void Sema::collectUnexpandedParameterPacks(TemplateArgument Arg,