https://github.com/zyn0217 updated https://github.com/llvm/llvm-project/pull/86265
>From 6e7b38b3e3f781e11db2fa5d552fdfb6123609df Mon Sep 17 00:00:00 2001 From: Younan Zhang <zyn7...@gmail.com> Date: Fri, 22 Mar 2024 17:34:08 +0800 Subject: [PATCH 01/10] [Sema] Preserve ContainsUnexpandedParameterPack in TransformLambdaExpr --- clang/docs/ReleaseNotes.rst | 2 + clang/include/clang/Sema/Sema.h | 8 +++ clang/lib/Sema/SemaTemplateVariadic.cpp | 16 +++++- clang/lib/Sema/TreeTransform.h | 18 ++++++ .../test/SemaTemplate/lambda-capture-pack.cpp | 57 +++++++++++++++++++ 5 files changed, 98 insertions(+), 3 deletions(-) diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 690fc7ed271a3..2d11a4b8c092a 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -344,6 +344,8 @@ Bug Fixes to C++ Support when one of the function had more specialized templates. Fixes (`#82509 <https://github.com/llvm/llvm-project/issues/82509>`_) and (`#74494 <https://github.com/llvm/llvm-project/issues/74494>`_) +- Fixed a crash where template parameter packs were not expanded correctly in a lambda being + used as a pattern of a folded expression. (#GH56852), (#GH85667) Bug Fixes to AST Handling ^^^^^^^^^^^^^^^^^^^^^^^^^ diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h index cfc1c3b349478..0d1a2e54840e5 100644 --- a/clang/include/clang/Sema/Sema.h +++ b/clang/include/clang/Sema/Sema.h @@ -11201,6 +11201,14 @@ class Sema final { void collectUnexpandedParameterPacks( QualType T, SmallVectorImpl<UnexpandedParameterPack> &Unexpanded); + /// Collect the set of unexpanded parameter packs from a lambda call operator. + /// + /// \param LambdaCall The lambda call operator that will be traversed to find + /// unexpanded parameter packs. + void collectUnexpandedParameterPacksFromLambda( + CXXMethodDecl *LambdaCall, + SmallVectorImpl<UnexpandedParameterPack> &Unexpanded); + /// Collect the set of unexpanded parameter packs within the given /// type. /// diff --git a/clang/lib/Sema/SemaTemplateVariadic.cpp b/clang/lib/Sema/SemaTemplateVariadic.cpp index 903fbfd18e779..638ceac4148ae 100644 --- a/clang/lib/Sema/SemaTemplateVariadic.cpp +++ b/clang/lib/Sema/SemaTemplateVariadic.cpp @@ -8,14 +8,15 @@ // This file implements semantic analysis for C++0x variadic templates. //===----------------------------------------------------------------------===/ -#include "clang/Sema/Sema.h" #include "TypeLocBuilder.h" +#include "clang/AST/ASTLambda.h" #include "clang/AST/Expr.h" #include "clang/AST/RecursiveASTVisitor.h" #include "clang/AST/TypeLoc.h" #include "clang/Sema/Lookup.h" #include "clang/Sema/ParsedTemplate.h" #include "clang/Sema/ScopeInfo.h" +#include "clang/Sema/Sema.h" #include "clang/Sema/SemaInternal.h" #include "clang/Sema/Template.h" #include <optional> @@ -61,8 +62,9 @@ namespace { public: explicit CollectUnexpandedParameterPacksVisitor( - SmallVectorImpl<UnexpandedParameterPack> &Unexpanded) - : Unexpanded(Unexpanded) {} + SmallVectorImpl<UnexpandedParameterPack> &Unexpanded, + bool InLambda = false) + : Unexpanded(Unexpanded), InLambda(InLambda) {} bool shouldWalkTypesOfTypeLocs() const { return false; } @@ -544,6 +546,14 @@ void Sema::collectUnexpandedParameterPacks(QualType T, CollectUnexpandedParameterPacksVisitor(Unexpanded).TraverseType(T); } +void Sema::collectUnexpandedParameterPacksFromLambda( + CXXMethodDecl *LambdaCall, + SmallVectorImpl<UnexpandedParameterPack> &Unexpanded) { + assert(isLambdaCallOperator(LambdaCall) && "Expected a lambda call operator"); + CollectUnexpandedParameterPacksVisitor(Unexpanded, /*InLambda=*/true) + .TraverseDecl(LambdaCall); +} + void Sema::collectUnexpandedParameterPacks(TypeLoc TL, SmallVectorImpl<UnexpandedParameterPack> &Unexpanded) { CollectUnexpandedParameterPacksVisitor(Unexpanded).TraverseTypeLoc(TL); diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h index 2d22692f3ab75..f5a859c57034a 100644 --- a/clang/lib/Sema/TreeTransform.h +++ b/clang/lib/Sema/TreeTransform.h @@ -13748,6 +13748,8 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) { } NewVDs.push_back(NewVD); getSema().addInitCapture(LSI, NewVD, C->getCaptureKind() == LCK_ByRef); + LSI->ContainsUnexpandedParameterPack |= + Init.get()->containsUnexpandedParameterPack(); } if (Invalid) @@ -13936,6 +13938,22 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) { /*IsInstantiation*/ true); SavedContext.pop(); + // The lambda may contain a pack that would be expanded by a fold expression + // outside. We should preserve the ContainsUnexpandedParameterPack flag here + // because CXXFoldExprs use it for the pattern. + // For example, + // + // []<class... Is>() { ([I = Is()]() {}, ...); } + // + // forgetting the flag will result in getPattern() of CXXFoldExpr returning + // null in terms of the inner lambda. + if (!LSICopy.ContainsUnexpandedParameterPack) { + llvm::SmallVector<UnexpandedParameterPack> UnexpandedPacks; + getSema().collectUnexpandedParameterPacksFromLambda(NewCallOperator, + UnexpandedPacks); + // Should we call DiagnoseUnexpandedParameterPacks() instead? + LSICopy.ContainsUnexpandedParameterPack = !UnexpandedPacks.empty(); + } return getSema().BuildLambdaExpr(E->getBeginLoc(), Body.get()->getEndLoc(), &LSICopy); } diff --git a/clang/test/SemaTemplate/lambda-capture-pack.cpp b/clang/test/SemaTemplate/lambda-capture-pack.cpp index 35b2ffcefea35..31d85e1689af1 100644 --- a/clang/test/SemaTemplate/lambda-capture-pack.cpp +++ b/clang/test/SemaTemplate/lambda-capture-pack.cpp @@ -23,3 +23,60 @@ namespace PR41576 { } static_assert(f(3, 4) == 6); // expected-note {{instantiation}} } + +namespace PR85667 { + +template <class T> +struct identity { + using type = T; +}; + +template <class = void> void f() { + + static_assert([]<class... Is>(Is... x) { + return ([I(x)] { + return I; + }() + ...); + }(1, 2) == 3); + + static_assert([]<class... Is>(Is... x) { + return ([](auto y = Is()) { return y + 1; } + ...); + }(0, 0, 0) == 3); + + []<class... Is>() { + return ([]() noexcept(Is()) { return 0; }() + ...); + }.template operator()<int, int>(); + + static_assert(__is_same(decltype([]<class... Is>() { + return ([]() -> decltype(Is()) { return {}; }(), + ...); + }.template operator()<int, char>()), + char)); + + []<class... Is>() { + return ([]<class... Ts>() -> decltype(Is()) { return Ts(); }() + ...); + // expected-error@-1 {{unexpanded parameter pack 'Ts'}} + }.template operator()<int, int>(); + + // Note that GCC and EDG reject this case currently. + // GCC says the fold expression "has no unexpanded parameter packs", while + // EDG says the constraint is not allowed on a non-template function. + // MSVC is happy with it. + []<class... Is>() { + ([]() + requires(Is()) + {}, + ...); + }.template operator()<bool, bool>(); + + // https://github.com/llvm/llvm-project/issues/56852 + []<class... Is>(Is...) { + ([] { + using T = identity<Is>::type; + }(), ...); + }(1, 2); +} + +template void f(); + +} >From e76fedd9fbe557f5c9a9f980a141c2ed31c24424 Mon Sep 17 00:00:00 2001 From: Younan Zhang <zyn7...@gmail.com> Date: Sat, 23 Mar 2024 19:39:37 +0800 Subject: [PATCH 02/10] Consider the captured pack variables - gh18873 --- clang/docs/ReleaseNotes.rst | 4 ++-- clang/lib/Sema/TreeTransform.h | 4 ++++ .../test/SemaTemplate/lambda-capture-pack.cpp | 21 +++++++++++++++++++ 3 files changed, 27 insertions(+), 2 deletions(-) diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 2d11a4b8c092a..41529cbc9bd9a 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -344,8 +344,8 @@ Bug Fixes to C++ Support when one of the function had more specialized templates. Fixes (`#82509 <https://github.com/llvm/llvm-project/issues/82509>`_) and (`#74494 <https://github.com/llvm/llvm-project/issues/74494>`_) -- Fixed a crash where template parameter packs were not expanded correctly in a lambda being - used as a pattern of a folded expression. (#GH56852), (#GH85667) +- Fixed a crash where template parameter packs were not expanded correctly in a lambda used + as the pattern of a folded expression. (#GH56852), (#GH85667), and partially fixes (#GH18873). Bug Fixes to AST Handling ^^^^^^^^^^^^^^^^^^^^^^^^^ diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h index f5a859c57034a..fb29e5111fc54 100644 --- a/clang/lib/Sema/TreeTransform.h +++ b/clang/lib/Sema/TreeTransform.h @@ -13817,6 +13817,10 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) { continue; } + if (auto *PVD = dyn_cast<VarDecl>(CapturedVar); + PVD && !C->isPackExpansion()) + LSI->ContainsUnexpandedParameterPack |= PVD->isParameterPack(); + // Capture the transformed variable. getSema().tryCaptureVariable(CapturedVar, C->getLocation(), Kind, EllipsisLoc); diff --git a/clang/test/SemaTemplate/lambda-capture-pack.cpp b/clang/test/SemaTemplate/lambda-capture-pack.cpp index 31d85e1689af1..8a81417b6daee 100644 --- a/clang/test/SemaTemplate/lambda-capture-pack.cpp +++ b/clang/test/SemaTemplate/lambda-capture-pack.cpp @@ -75,6 +75,27 @@ template <class = void> void f() { using T = identity<Is>::type; }(), ...); }(1, 2); + + // https://github.com/llvm/llvm-project/issues/18873 + [](auto ...y) { + ([y] { }, ...); + }(); + + [](auto ...x) { + ([&](auto ...y) { + // FIXME: This now hits the assertion with `PackIdx != -1 && "found declaration pack but not pack expanding"' + // in Sema::FindInstantiatedDecl. + // This is because the captured variable x has been expanded while transforming + // the outermost lambda call, but the expansion then gets holded off while transforming + // the folded expression. Then we would hit the assertion when instantiating the captured variable + // in TransformLambdaExpr. + // I think this is supposed to be ill-formed, but GCC and MSVC currently accept this. + // If x gets expanded with non-empty arguments, then GCC and MSVC will reject it - we probably + // miss a diagnostic for it. + // ([x, y] { }, ...); + ([x..., y] { }, ...); + })(); + }(); } template void f(); >From faf5d8710ba0177685cd65c6b81cf79b97223e4b Mon Sep 17 00:00:00 2001 From: Younan Zhang <zyn7...@gmail.com> Date: Sat, 23 Mar 2024 23:00:51 +0800 Subject: [PATCH 03/10] comments --- clang/lib/Sema/TreeTransform.h | 4 ++++ clang/test/SemaTemplate/lambda-capture-pack.cpp | 12 ++++++------ 2 files changed, 10 insertions(+), 6 deletions(-) diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h index 0e2ea13d64d46..31592e6557f0d 100644 --- a/clang/lib/Sema/TreeTransform.h +++ b/clang/lib/Sema/TreeTransform.h @@ -13786,6 +13786,8 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) { } NewVDs.push_back(NewVD); getSema().addInitCapture(LSI, NewVD, C->getCaptureKind() == LCK_ByRef); + // The initializer might be expanded later. This may happen + // if the lambda is within a folded expression. LSI->ContainsUnexpandedParameterPack |= Init.get()->containsUnexpandedParameterPack(); } @@ -13855,6 +13857,8 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) { continue; } + // The captured variable might be expanded later. This may happen + // if the lambda is within a folded expression. if (auto *PVD = dyn_cast<VarDecl>(CapturedVar); PVD && !C->isPackExpansion()) LSI->ContainsUnexpandedParameterPack |= PVD->isParameterPack(); diff --git a/clang/test/SemaTemplate/lambda-capture-pack.cpp b/clang/test/SemaTemplate/lambda-capture-pack.cpp index 8a81417b6daee..506902bc99dc6 100644 --- a/clang/test/SemaTemplate/lambda-capture-pack.cpp +++ b/clang/test/SemaTemplate/lambda-capture-pack.cpp @@ -83,15 +83,15 @@ template <class = void> void f() { [](auto ...x) { ([&](auto ...y) { - // FIXME: This now hits the assertion with `PackIdx != -1 && "found declaration pack but not pack expanding"' + // FIXME: This now hits assertion `PackIdx != -1 && "found declaration pack but not pack expanding"' // in Sema::FindInstantiatedDecl. // This is because the captured variable x has been expanded while transforming - // the outermost lambda call, but the expansion then gets holded off while transforming - // the folded expression. Then we would hit the assertion when instantiating the captured variable - // in TransformLambdaExpr. + // the outermost lambda call, but the expansion is held off while transforming + // the folded expression. Then, we would hit the assertion when instantiating the + // captured variable in TransformLambdaExpr. // I think this is supposed to be ill-formed, but GCC and MSVC currently accept this. - // If x gets expanded with non-empty arguments, then GCC and MSVC will reject it - we probably - // miss a diagnostic for it. + // However, if x gets expanded with non-empty arguments, then GCC and MSVC will reject it - + // we probably need a diagnostic for it. // ([x, y] { }, ...); ([x..., y] { }, ...); })(); >From c5765ec62f1d32b1cd817c8c78ef7b2d21bf296e Mon Sep 17 00:00:00 2001 From: Younan Zhang <zyn7...@gmail.com> Date: Sun, 24 Mar 2024 00:15:14 +0800 Subject: [PATCH 04/10] format --- clang/lib/Sema/TreeTransform.h | 34 ++++++++++++++++++++++++---------- 1 file changed, 24 insertions(+), 10 deletions(-) diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h index 31592e6557f0d..e2ec9b7085737 100644 --- a/clang/lib/Sema/TreeTransform.h +++ b/clang/lib/Sema/TreeTransform.h @@ -13786,8 +13786,9 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) { } NewVDs.push_back(NewVD); getSema().addInitCapture(LSI, NewVD, C->getCaptureKind() == LCK_ByRef); - // The initializer might be expanded later. This may happen - // if the lambda is within a folded expression. + // If the lambda is written within a fold expression, the initializer + // may be expanded later. Preserve the ContainsUnexpandedParameterPack + // flag because CXXFoldExpr uses it for the pattern. LSI->ContainsUnexpandedParameterPack |= Init.get()->containsUnexpandedParameterPack(); } @@ -13848,6 +13849,17 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) { EllipsisLoc = C->getEllipsisLoc(); } +#if 0 + else if (auto *PVD = cast<VarDecl>(C->getCapturedVar()); PVD->isParameterPack()) { + // If the lambda is written within a fold expression, the captured + // variable may be expanded later. Preserve the + // ContainsUnexpandedParameterPack flag because CXXFoldExpr uses it for the + // pattern. + LSI->ContainsUnexpandedParameterPack |= true; + getSema().tryCaptureVariable(PVD, C->getLocation(), Kind, EllipsisLoc); + continue; + } +#endif // Transform the captured variable. auto *CapturedVar = cast_or_null<ValueDecl>( @@ -13857,11 +13869,15 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) { continue; } - // The captured variable might be expanded later. This may happen - // if the lambda is within a folded expression. + // If the lambda is written within a fold expression, the captured + // variable may be expanded later. Preserve the + // ContainsUnexpandedParameterPack flag because CXXFoldExpr uses it for the + // pattern. +#if 1 if (auto *PVD = dyn_cast<VarDecl>(CapturedVar); PVD && !C->isPackExpansion()) LSI->ContainsUnexpandedParameterPack |= PVD->isParameterPack(); +#endif // Capture the transformed variable. getSema().tryCaptureVariable(CapturedVar, C->getLocation(), Kind, @@ -13984,12 +14000,10 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) { /*IsInstantiation*/ true); SavedContext.pop(); - // The lambda may contain a pack that would be expanded by a fold expression - // outside. We should preserve the ContainsUnexpandedParameterPack flag here - // because CXXFoldExprs use it for the pattern. - // For example, + // The lambda function might contain a pack that would be expanded by a fold + // expression outside. For example, // - // []<class... Is>() { ([I = Is()]() {}, ...); } + // []<class... Is>() { ([](auto P = Is()) {}, ...); } // // forgetting the flag will result in getPattern() of CXXFoldExpr returning // null in terms of the inner lambda. @@ -13997,7 +14011,7 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) { llvm::SmallVector<UnexpandedParameterPack> UnexpandedPacks; getSema().collectUnexpandedParameterPacksFromLambda(NewCallOperator, UnexpandedPacks); - // Should we call DiagnoseUnexpandedParameterPacks() instead? + // FIXME: Should we call DiagnoseUnexpandedParameterPacks() instead? LSICopy.ContainsUnexpandedParameterPack = !UnexpandedPacks.empty(); } return getSema().BuildLambdaExpr(E->getBeginLoc(), Body.get()->getEndLoc(), >From 6c2d311938839092f8fd1c5334673c6e35fe4651 Mon Sep 17 00:00:00 2001 From: Younan Zhang <zyn7...@gmail.com> Date: Fri, 3 May 2024 21:50:42 +0800 Subject: [PATCH 05/10] Retain the 'unexpanded' Decls --- .../lib/Sema/SemaTemplateInstantiateDecl.cpp | 8 ++++++ .../test/SemaTemplate/lambda-capture-pack.cpp | 26 +++++++++---------- 2 files changed, 21 insertions(+), 13 deletions(-) diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp index 787a485e0b2f8..ac96449221384 100644 --- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp +++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp @@ -6221,6 +6221,14 @@ NamedDecl *Sema::FindInstantiatedDecl(SourceLocation Loc, NamedDecl *D, return cast<NamedDecl>(FD); int PackIdx = ArgumentPackSubstitutionIndex; + // FIXME: Move it elsewhere e.g. TreeTransform::TransformDecl. + // This is for #18873. + if (PackIdx == -1) { + LocalInstantiationScope LIS(*this, /*CombineWithOuterScope=*/false); + MultiLevelTemplateArgumentList FakeArgs; + FakeArgs.addOuterRetainedLevels(D->getTemplateDepth() + 1); + return cast_if_present<NamedDecl>(SubstDecl(D, CurContext, FakeArgs)); + } assert(PackIdx != -1 && "found declaration pack but not pack expanding"); typedef LocalInstantiationScope::DeclArgumentPack DeclArgumentPack; diff --git a/clang/test/SemaTemplate/lambda-capture-pack.cpp b/clang/test/SemaTemplate/lambda-capture-pack.cpp index 506902bc99dc6..12cb2ba6cb86e 100644 --- a/clang/test/SemaTemplate/lambda-capture-pack.cpp +++ b/clang/test/SemaTemplate/lambda-capture-pack.cpp @@ -83,21 +83,21 @@ template <class = void> void f() { [](auto ...x) { ([&](auto ...y) { - // FIXME: This now hits assertion `PackIdx != -1 && "found declaration pack but not pack expanding"' - // in Sema::FindInstantiatedDecl. - // This is because the captured variable x has been expanded while transforming - // the outermost lambda call, but the expansion is held off while transforming - // the folded expression. Then, we would hit the assertion when instantiating the - // captured variable in TransformLambdaExpr. - // I think this is supposed to be ill-formed, but GCC and MSVC currently accept this. - // However, if x gets expanded with non-empty arguments, then GCC and MSVC will reject it - - // we probably need a diagnostic for it. - // ([x, y] { }, ...); ([x..., y] { }, ...); - })(); - }(); + })(1); + }(2, 'b'); + + [](auto ...x) { // #outer + ([&](auto ...y) { // #inner + ([x, y] { }, ...); + // expected-error@-1 {{parameter pack 'y' that has a different length (4 vs. 3) from outer parameter packs}} + // expected-note-re@#inner {{function template specialization {{.*}} requested here}} + // expected-note-re@#outer {{function template specialization {{.*}} requested here}} + // expected-note-re@#instantiate-f {{function template specialization {{.*}} requested here}} + })('a', 'b', 'c'); + }(0, 1, 2, 3); } -template void f(); +template void f(); // #instantiate-f } >From 1ac5ca73a1dd6084cae9ec54546f56fc18d7e0bc Mon Sep 17 00:00:00 2001 From: Younan Zhang <zyn7...@gmail.com> Date: Fri, 3 May 2024 22:11:49 +0800 Subject: [PATCH 06/10] Update ReleaseNotes --- clang/docs/ReleaseNotes.rst | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 81a6d67f42f7e..dd488f7ec17d1 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -561,7 +561,7 @@ Bug Fixes to C++ Support - Fixed a crash when trying to evaluate a user-defined ``static_assert`` message whose ``size()`` function returns a large or negative value. Fixes (#GH89407). - Fixed a crash where template parameter packs were not expanded correctly in a lambda used - as the pattern of a folded expression. (#GH56852), (#GH85667), and partially fixed (#GH18873). + as the pattern of a folded expression. (#GH56852), (#GH85667) and (#GH18873). Bug Fixes to AST Handling ^^^^^^^^^^^^^^^^^^^^^^^^^ >From db36bc87d2a5bb64a918a53636f3f97524f883ad Mon Sep 17 00:00:00 2001 From: Younan Zhang <zyn7...@gmail.com> Date: Wed, 8 May 2024 09:50:01 +0800 Subject: [PATCH 07/10] Cleanup & silence the unused-expression warning --- clang/lib/Sema/TreeTransform.h | 18 ++---------------- .../test/SemaTemplate/lambda-capture-pack.cpp | 12 +++++++++--- 2 files changed, 11 insertions(+), 19 deletions(-) diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h index ec14129259f83..e765d25ee606f 100644 --- a/clang/lib/Sema/TreeTransform.h +++ b/clang/lib/Sema/TreeTransform.h @@ -14092,17 +14092,6 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) { EllipsisLoc = C->getEllipsisLoc(); } -#if 0 - else if (auto *PVD = cast<VarDecl>(C->getCapturedVar()); PVD->isParameterPack()) { - // If the lambda is written within a fold expression, the captured - // variable may be expanded later. Preserve the - // ContainsUnexpandedParameterPack flag because CXXFoldExpr uses it for the - // pattern. - LSI->ContainsUnexpandedParameterPack |= true; - getSema().tryCaptureVariable(PVD, C->getLocation(), Kind, EllipsisLoc); - continue; - } -#endif // Transform the captured variable. auto *CapturedVar = cast_or_null<ValueDecl>( @@ -14116,11 +14105,8 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) { // variable may be expanded later. Preserve the // ContainsUnexpandedParameterPack flag because CXXFoldExpr uses it for the // pattern. -#if 1 - if (auto *PVD = dyn_cast<VarDecl>(CapturedVar); - PVD && !C->isPackExpansion()) - LSI->ContainsUnexpandedParameterPack |= PVD->isParameterPack(); -#endif + LSI->ContainsUnexpandedParameterPack |= + cast<VarDecl>(CapturedVar)->isParameterPack(); // Capture the transformed variable. getSema().tryCaptureVariable(CapturedVar, C->getLocation(), Kind, diff --git a/clang/test/SemaTemplate/lambda-capture-pack.cpp b/clang/test/SemaTemplate/lambda-capture-pack.cpp index 12cb2ba6cb86e..7b22c724eb20e 100644 --- a/clang/test/SemaTemplate/lambda-capture-pack.cpp +++ b/clang/test/SemaTemplate/lambda-capture-pack.cpp @@ -78,18 +78,24 @@ template <class = void> void f() { // https://github.com/llvm/llvm-project/issues/18873 [](auto ...y) { - ([y] { }, ...); + ([y] { }(), ...); }(); [](auto ...x) { ([&](auto ...y) { - ([x..., y] { }, ...); + ([x..., y] { }(), ...); })(1); }(2, 'b'); + [](auto ...x) { + ([&](auto ...y) { + ([x, y] { }(), ...); + })(1, 'a'); + }(2, 'b'); + [](auto ...x) { // #outer ([&](auto ...y) { // #inner - ([x, y] { }, ...); + ([x, y] { }(), ...); // expected-error@-1 {{parameter pack 'y' that has a different length (4 vs. 3) from outer parameter packs}} // expected-note-re@#inner {{function template specialization {{.*}} requested here}} // expected-note-re@#outer {{function template specialization {{.*}} requested here}} >From 66acffb605aa724f59a2667bc3e542a23163e1e3 Mon Sep 17 00:00:00 2001 From: Younan Zhang <zyn7...@gmail.com> Date: Fri, 24 May 2024 13:33:20 +0800 Subject: [PATCH 08/10] Fix the CI --- clang/lib/Sema/TreeTransform.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h index e765d25ee606f..3be68d8d251f3 100644 --- a/clang/lib/Sema/TreeTransform.h +++ b/clang/lib/Sema/TreeTransform.h @@ -14105,8 +14105,8 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) { // variable may be expanded later. Preserve the // ContainsUnexpandedParameterPack flag because CXXFoldExpr uses it for the // pattern. - LSI->ContainsUnexpandedParameterPack |= - cast<VarDecl>(CapturedVar)->isParameterPack(); + if (auto *VD = dyn_cast<VarDecl>(CapturedVar); VD && !C->isPackExpansion()) + LSI->ContainsUnexpandedParameterPack |= VD->isParameterPack(); // Capture the transformed variable. getSema().tryCaptureVariable(CapturedVar, C->getLocation(), Kind, >From 5285c104ed526311edc4a54842ca7844410d4780 Mon Sep 17 00:00:00 2001 From: Younan Zhang <zyn7...@gmail.com> Date: Fri, 24 May 2024 13:34:00 +0800 Subject: [PATCH 09/10] Fix typos --- clang/lib/Sema/SemaTemplateDeduction.cpp | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/clang/lib/Sema/SemaTemplateDeduction.cpp b/clang/lib/Sema/SemaTemplateDeduction.cpp index 0b6375001f532..2af3c44f49b3c 100644 --- a/clang/lib/Sema/SemaTemplateDeduction.cpp +++ b/clang/lib/Sema/SemaTemplateDeduction.cpp @@ -4296,7 +4296,7 @@ TemplateDeductionResult Sema::DeduceTemplateArguments( // Deduce an argument of type ParamType from an expression with index ArgIdx. auto DeduceCallArgument = [&](QualType ParamType, unsigned ArgIdx, - bool ExplicitObjetArgument) { + bool ExplicitObjectArgument) { // C++ [demp.deduct.call]p1: (DR1391) // Template argument deduction is done by comparing each function template // parameter that contains template-parameters that participate in @@ -4304,7 +4304,7 @@ TemplateDeductionResult Sema::DeduceTemplateArguments( if (!hasDeducibleTemplateParameters(*this, FunctionTemplate, ParamType)) return TemplateDeductionResult::Success; - if (ExplicitObjetArgument) { + if (ExplicitObjectArgument) { // ... with the type of the corresponding argument return DeduceTemplateArgumentsFromCallArgument( *this, TemplateParams, FirstInnerIndex, ParamType, ObjectType, >From b2d28364d1729b3f90b37905b91554b9a5d75423 Mon Sep 17 00:00:00 2001 From: Younan Zhang <zyn7...@gmail.com> Date: Thu, 18 Jul 2024 14:28:52 +0800 Subject: [PATCH 10/10] Fixup --- .../lib/Sema/SemaTemplateInstantiateDecl.cpp | 8 ----- clang/lib/Sema/TreeTransform.h | 25 +++++++--------- .../test/SemaTemplate/lambda-capture-pack.cpp | 29 +++++++++++++++---- 3 files changed, 34 insertions(+), 28 deletions(-) diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp index 896e38d45326e..01432301633ed 100644 --- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp +++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp @@ -6113,14 +6113,6 @@ NamedDecl *Sema::FindInstantiatedDecl(SourceLocation Loc, NamedDecl *D, return cast<NamedDecl>(FD); int PackIdx = ArgumentPackSubstitutionIndex; - // FIXME: Move it elsewhere e.g. TreeTransform::TransformDecl. - // This is for #18873. - if (PackIdx == -1) { - LocalInstantiationScope LIS(*this, /*CombineWithOuterScope=*/false); - MultiLevelTemplateArgumentList FakeArgs; - FakeArgs.addOuterRetainedLevels(D->getTemplateDepth() + 1); - return cast_if_present<NamedDecl>(SubstDecl(D, CurContext, FakeArgs)); - } assert(PackIdx != -1 && "found declaration pack but not pack expanding"); typedef LocalInstantiationScope::DeclArgumentPack DeclArgumentPack; diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h index ba074bc636361..1afe05d9ad524 100644 --- a/clang/lib/Sema/TreeTransform.h +++ b/clang/lib/Sema/TreeTransform.h @@ -14443,9 +14443,7 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) { } NewVDs.push_back(NewVD); getSema().addInitCapture(LSI, NewVD, C->getCaptureKind() == LCK_ByRef); - // If the lambda is written within a fold expression, the initializer - // may be expanded later. Preserve the ContainsUnexpandedParameterPack - // flag because CXXFoldExpr uses it for the pattern. + // The Init expression might be expanded by an outer fold expression. LSI->ContainsUnexpandedParameterPack |= Init.get()->containsUnexpandedParameterPack(); } @@ -14515,10 +14513,7 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) { continue; } - // If the lambda is written within a fold expression, the captured - // variable may be expanded later. Preserve the - // ContainsUnexpandedParameterPack flag because CXXFoldExpr uses it for the - // pattern. + // The captured pack might be expanded by an outer fold expression. if (auto *VD = dyn_cast<VarDecl>(CapturedVar); VD && !C->isPackExpansion()) LSI->ContainsUnexpandedParameterPack |= VD->isParameterPack(); @@ -14574,6 +14569,8 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) { if (NewCallOpType.isNull()) return ExprError(); + LSI->ContainsUnexpandedParameterPack |= + NewCallOpType->containsUnexpandedParameterPack(); NewCallOpTSI = NewCallOpTLBuilder.getTypeSourceInfo(getSema().Context, NewCallOpType); } @@ -14648,18 +14645,18 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) { /*IsInstantiation*/ true); SavedContext.pop(); - // The lambda function might contain a pack that would be expanded by a fold - // expression outside. For example, + // Parts other than the capture e.g. the lambda body might still contain a + // pattern that an outer fold expression would expand. // - // []<class... Is>() { ([](auto P = Is()) {}, ...); } - // - // forgetting the flag will result in getPattern() of CXXFoldExpr returning - // null in terms of the inner lambda. + // We don't have a way to propagate up the ContainsUnexpandedParameterPack + // flag from a Stmt, so we have to revisit the lambda. if (!LSICopy.ContainsUnexpandedParameterPack) { llvm::SmallVector<UnexpandedParameterPack> UnexpandedPacks; getSema().collectUnexpandedParameterPacksFromLambda(NewCallOperator, UnexpandedPacks); - // FIXME: Should we call DiagnoseUnexpandedParameterPacks() instead? + // FIXME: Should we call Sema::DiagnoseUnexpandedParameterPacks() instead? + // Unfortunately, that requires the LambdaScopeInfo to exist, which has been + // removed by ActOnFinishFunctionBody(). LSICopy.ContainsUnexpandedParameterPack = !UnexpandedPacks.empty(); } // Recompute the dependency of the lambda so that we can defer the lambda call diff --git a/clang/test/SemaTemplate/lambda-capture-pack.cpp b/clang/test/SemaTemplate/lambda-capture-pack.cpp index 7b22c724eb20e..6d2ab50827759 100644 --- a/clang/test/SemaTemplate/lambda-capture-pack.cpp +++ b/clang/test/SemaTemplate/lambda-capture-pack.cpp @@ -76,7 +76,6 @@ template <class = void> void f() { }(), ...); }(1, 2); - // https://github.com/llvm/llvm-project/issues/18873 [](auto ...y) { ([y] { }(), ...); }(); @@ -87,11 +86,28 @@ template <class = void> void f() { })(1); }(2, 'b'); - [](auto ...x) { - ([&](auto ...y) { - ([x, y] { }(), ...); - })(1, 'a'); - }(2, 'b'); +#if 0 + // https://github.com/llvm/llvm-project/issues/18873 + [](auto ...x) { // #1 + ([&](auto ...y) { // #2 + ([x, y] { }(), ...); // #3 + })(1, 'a'); // #4 + }(2, 'b'); // #5 + + // We run into another crash for the above lambda because of the absence of a + // mechanism that rebuilds an unexpanded pack from an expanded Decls. + // + // Basically, this happens after `x` at #1 being expanded when the template + // arguments at #5, deduced as <int, char>, are ready. When we want to + // instantiate the body of #1, we first instantiate the CallExpr at #4, which + // boils down to the lambda's instantiation at #2. To that end, we have to + // instantiate the body of it, which turns out to be #3. #3 is a CXXFoldExpr, + // and we immediately have to hold off on the expansion because we don't have + // corresponding template arguments for it. Therefore, we want to rebuild a + // CXXFoldExpr, which requires another pattern transformation of the lambda + // inside #3. Then we need to find an unexpanded form of such a Decl of x at + // the time of transforming the capture, which is impossible because the + // instantiated form has been expanded at #1! [](auto ...x) { // #outer ([&](auto ...y) { // #inner @@ -102,6 +118,7 @@ template <class = void> void f() { // expected-note-re@#instantiate-f {{function template specialization {{.*}} requested here}} })('a', 'b', 'c'); }(0, 1, 2, 3); +#endif } template void f(); // #instantiate-f _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
