https://github.com/MaskRay created https://github.com/llvm/llvm-project/pull/225584
#132748 narrowed PackIndex to 15 bits when adding Final, leaving a bit unused, so a type pack with 32768 or more elements stores a wrapped pack index. The node then keys differently from its lookup, failing the UniquingSet insert assertion. Restore the 16-bit width, matching SubstPackType's 16-bit NumArgs. Fix assertion failure godbolt.org/z/9r1jEqqob Aided by Opus 5.5 >From 637c57cc0a8e77e30ec22d9c31b34ff5f058e3aa Mon Sep 17 00:00:00 2001 From: Fangrui Song <[email protected]> Date: Tue, 22 Sep 2026 20:34:24 -0700 Subject: [PATCH] [clang] Widen SubstTemplateTypeParmType::PackIndex to 16 bits #132748 narrowed PackIndex to 15 bits when adding Final, leaving a bit unused, so a type pack with 32768 or more elements stores a wrapped pack index. The node then keys differently from its lookup, failing the UniquingSet insert assertion. Restore the 16-bit width, matching SubstPackType's 16-bit NumArgs. Fix assertion failure godbolt.org/z/9r1jEqqob Aided by Opus 5.5 --- clang/include/clang/AST/TypeBase.h | 2 +- clang/test/SemaCXX/make_integer_seq.cpp | 5 +++++ 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/clang/include/clang/AST/TypeBase.h b/clang/include/clang/AST/TypeBase.h index 28f102fdaf534c..5acda5ad6e4a8d 100644 --- a/clang/include/clang/AST/TypeBase.h +++ b/clang/include/clang/AST/TypeBase.h @@ -2270,7 +2270,7 @@ class alignas(TypeAlignment) Type : public ExtQualsTypeCommonBase { /// increments towards the beginning. /// Positive non-zero number represents the index + 1. /// Zero means this is not substituted from an expansion. - unsigned PackIndex : 15; + unsigned PackIndex : 16; }; class SubstPackTypeBitfields { diff --git a/clang/test/SemaCXX/make_integer_seq.cpp b/clang/test/SemaCXX/make_integer_seq.cpp index 71b7b8260d4abc..58e218403a8b51 100644 --- a/clang/test/SemaCXX/make_integer_seq.cpp +++ b/clang/test/SemaCXX/make_integer_seq.cpp @@ -50,3 +50,8 @@ __make_integer_seq<f, int, 0> x; // expected-error{{template template parameter __make_integer_seq<__make_integer_seq, int, 10> PR28494; // expected-note{{different template parameters}} // expected-error@make_integer_seq.cpp:* {{template argument for template template parameter must be a class template or type alias template}} + +// The largest type pack whose pack indices fit in SubstTemplateTypeParmType. +template <class... Ts> using Expand = void(Ts...); +template <class T, T... I> struct ExpandSeq { using type = Expand<decltype(I)...>; }; +using LargePack = __make_integer_seq<ExpandSeq, int, 65535>::type; _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
