[clang] [clang] Do not substitute parameter pack while retaining the pack expansion (PR #108197)
Utkarsh Saxena via cfe-commits
cfe-commits at lists.llvm.org
Thu Sep 12 04:06:03 PDT 2024
https://github.com/usx95 updated https://github.com/llvm/llvm-project/pull/108197
>From 5901d82ea0543074853b963f7dc9106a6fe3bcee Mon Sep 17 00:00:00 2001
From: Utkarsh Saxena <usx at google.com>
Date: Wed, 11 Sep 2024 11:33:45 +0000
Subject: [PATCH 1/7] [clang] Do not expand pack while retaining expansion
---
clang/lib/Sema/TreeTransform.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 0daf620b4123e4..a40673b04764da 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -4361,7 +4361,7 @@ bool TreeTransform<Derived>::TransformExprs(Expr *const *Inputs,
// forgetting the partially-substituted parameter pack.
if (RetainExpansion) {
ForgetPartiallySubstitutedPackRAII Forget(getDerived());
-
+ Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), -1);
ExprResult Out = getDerived().TransformExpr(Pattern);
if (Out.isInvalid())
return true;
>From 97fbf34c3edd09348fb48b4dc66f1d854516e8ef Mon Sep 17 00:00:00 2001
From: Utkarsh Saxena <usx at google.com>
Date: Wed, 11 Sep 2024 11:59:58 +0000
Subject: [PATCH 2/7] Add comment
---
clang/lib/Sema/TreeTransform.h | 1 +
1 file changed, 1 insertion(+)
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index a40673b04764da..0de43d2127b12f 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -4361,6 +4361,7 @@ bool TreeTransform<Derived>::TransformExprs(Expr *const *Inputs,
// forgetting the partially-substituted parameter pack.
if (RetainExpansion) {
ForgetPartiallySubstitutedPackRAII Forget(getDerived());
+ // Simple transform producing another pack expansion.
Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), -1);
ExprResult Out = getDerived().TransformExpr(Pattern);
if (Out.isInvalid())
>From ab756525ab4a5f71ee5d3703238a1f9188a376e1 Mon Sep 17 00:00:00 2001
From: Utkarsh Saxena <usx at google.com>
Date: Wed, 11 Sep 2024 15:45:40 +0000
Subject: [PATCH 3/7] Add tests
---
clang/test/SemaCXX/GH107560.cpp | 14 ++++++++++++++
1 file changed, 14 insertions(+)
create mode 100644 clang/test/SemaCXX/GH107560.cpp
diff --git a/clang/test/SemaCXX/GH107560.cpp b/clang/test/SemaCXX/GH107560.cpp
new file mode 100644
index 00000000000000..faaa7004e06cf9
--- /dev/null
+++ b/clang/test/SemaCXX/GH107560.cpp
@@ -0,0 +1,14 @@
+// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify %s
+// expected-no-diagnostics
+
+int bar(...);
+
+template <int> struct Int {};
+
+template <class ...T>
+consteval auto foo(T... x) -> decltype(bar(T(x)...)) { return 10; }
+
+template <class ...T>
+constexpr auto baz(Int<foo<T>(T())>... x) -> int { return 1; }
+
+static_assert(baz<Int<1>, Int<2>, Int<3>>(Int<10>(), Int<10>(), Int<10>()) == 1);
>From 600a9259bf087c5f3b6e881211da69013aca018e Mon Sep 17 00:00:00 2001
From: Utkarsh Saxena <usx at google.com>
Date: Wed, 11 Sep 2024 16:27:49 +0000
Subject: [PATCH 4/7] Move ArgumentPackSubstitutionIndexRAII to
ForgetPartiallySubstitutedPackRAII
---
clang/lib/Sema/TreeTransform.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 0de43d2127b12f..1538f87ac27358 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -113,9 +113,11 @@ class TreeTransform {
class ForgetPartiallySubstitutedPackRAII {
Derived &Self;
TemplateArgument Old;
+ Sema::ArgumentPackSubstitutionIndexRAII ResetPackSubstIndex;
public:
- ForgetPartiallySubstitutedPackRAII(Derived &Self) : Self(Self) {
+ ForgetPartiallySubstitutedPackRAII(Derived &Self)
+ : Self(Self), ResetPackSubstIndex(Self.getSema(), -1) {
Old = Self.ForgetPartiallySubstitutedPack();
}
@@ -4361,8 +4363,6 @@ bool TreeTransform<Derived>::TransformExprs(Expr *const *Inputs,
// forgetting the partially-substituted parameter pack.
if (RetainExpansion) {
ForgetPartiallySubstitutedPackRAII Forget(getDerived());
- // Simple transform producing another pack expansion.
- Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), -1);
ExprResult Out = getDerived().TransformExpr(Pattern);
if (Out.isInvalid())
return true;
>From 6cd618e295e984f2dd1924407fe64553549e6fcb Mon Sep 17 00:00:00 2001
From: Utkarsh Saxena <usx at google.com>
Date: Wed, 11 Sep 2024 16:31:18 +0000
Subject: [PATCH 5/7] remove space
---
clang/lib/Sema/TreeTransform.h | 1 +
1 file changed, 1 insertion(+)
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 1538f87ac27358..aa3e2308828bec 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -4363,6 +4363,7 @@ bool TreeTransform<Derived>::TransformExprs(Expr *const *Inputs,
// forgetting the partially-substituted parameter pack.
if (RetainExpansion) {
ForgetPartiallySubstitutedPackRAII Forget(getDerived());
+
ExprResult Out = getDerived().TransformExpr(Pattern);
if (Out.isInvalid())
return true;
>From 98bf2f3d7d7c2746b6d2e5f7921b6947cd598d3b Mon Sep 17 00:00:00 2001
From: Utkarsh Saxena <usx at google.com>
Date: Thu, 12 Sep 2024 09:19:43 +0000
Subject: [PATCH 6/7] move test to existing file; add comment;
---
clang/lib/Sema/TreeTransform.h | 2 ++
clang/test/SemaCXX/GH107560.cpp | 14 --------------
clang/test/SemaTemplate/pack-deduction.cpp | 14 ++++++++++++++
3 files changed, 16 insertions(+), 14 deletions(-)
delete mode 100644 clang/test/SemaCXX/GH107560.cpp
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index aa3e2308828bec..1ca5f58c874586 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -113,6 +113,8 @@ class TreeTransform {
class ForgetPartiallySubstitutedPackRAII {
Derived &Self;
TemplateArgument Old;
+ // Set the pack expansion index to -1 to avoid pack substitution and
+ // indicate that parameter packs should be instantiated as themselves.
Sema::ArgumentPackSubstitutionIndexRAII ResetPackSubstIndex;
public:
diff --git a/clang/test/SemaCXX/GH107560.cpp b/clang/test/SemaCXX/GH107560.cpp
deleted file mode 100644
index faaa7004e06cf9..00000000000000
--- a/clang/test/SemaCXX/GH107560.cpp
+++ /dev/null
@@ -1,14 +0,0 @@
-// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify %s
-// expected-no-diagnostics
-
-int bar(...);
-
-template <int> struct Int {};
-
-template <class ...T>
-consteval auto foo(T... x) -> decltype(bar(T(x)...)) { return 10; }
-
-template <class ...T>
-constexpr auto baz(Int<foo<T>(T())>... x) -> int { return 1; }
-
-static_assert(baz<Int<1>, Int<2>, Int<3>>(Int<10>(), Int<10>(), Int<10>()) == 1);
diff --git a/clang/test/SemaTemplate/pack-deduction.cpp b/clang/test/SemaTemplate/pack-deduction.cpp
index e42709820e9cff..28fb127a386441 100644
--- a/clang/test/SemaTemplate/pack-deduction.cpp
+++ b/clang/test/SemaTemplate/pack-deduction.cpp
@@ -185,3 +185,17 @@ void Run() {
Outer<void>::Inner<0>().Test(1,1);
}
}
+
+namespace GH107560 {
+int bar(...);
+
+template <int> struct Int {};
+
+template <class ...T>
+constexpr auto foo(T... x) -> decltype(bar(T(x)...)) { return 10; }
+
+template <class ...T>
+constexpr auto baz(Int<foo<T>(T())>... x) -> int { return 1; }
+
+static_assert(baz<Int<1>, Int<2>, Int<3>>(Int<10>(), Int<10>(), Int<10>()) == 1, "");
+}
>From 12a03c4fdceeccfb2e8f2ef448a38ba946faf7fc Mon Sep 17 00:00:00 2001
From: Utkarsh Saxena <usx at google.com>
Date: Thu, 12 Sep 2024 11:04:40 +0000
Subject: [PATCH 7/7] release notes
---
clang/docs/ReleaseNotes.rst | 2 ++
1 file changed, 2 insertions(+)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 59ccdf1e15cd81..af541fadbfb147 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -380,6 +380,8 @@ Bug Fixes to C++ Support
- Fixed a bug where defaulted comparison operators would remove ``const`` from base classes. (#GH102588)
- Fix a crash when using ``source_location`` in the trailing return type of a lambda expression. (#GH67134)
- A follow-up fix was added for (#GH61460), as the previous fix was not entirely correct. (#GH86361)
+- Fixed a crash when clang tries to subtitute parameter pack while retaining the parameter
+ pack. #GH63819, #GH107560
Bug Fixes to AST Handling
^^^^^^^^^^^^^^^^^^^^^^^^^
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