[clang] [Clang][Sema] Abbreviated function templates do not append invented parameters to empty template parameter lists (PR #80864)
Krystian Stasiowski via cfe-commits
cfe-commits at lists.llvm.org
Thu Feb 8 07:20:24 PST 2024
https://github.com/sdkrystian updated https://github.com/llvm/llvm-project/pull/80864
>From 908b3a129ec02a7ecae0ed3b8386e4e505274315 Mon Sep 17 00:00:00 2001
From: Krystian Stasiowski <sdkrystian at gmail.com>
Date: Tue, 6 Feb 2024 11:08:04 -0500
Subject: [PATCH] [Clang][Sema] Abbreviated function templates do not append
invented parameters to empty template parameter lists
---
clang/docs/ReleaseNotes.rst | 2 ++
clang/include/clang/AST/DeclTemplate.h | 1 +
clang/lib/AST/DeclPrinter.cpp | 4 ++++
clang/lib/Sema/SemaDecl.cpp | 2 +-
clang/lib/Sema/SemaDeclCXX.cpp | 11 ++++++++-
clang/test/AST/ast-print-method-decl.cpp | 3 +--
.../CXX/dcl.decl/dcl.meaning/dcl.fct/p23.cpp | 24 +++++++++++++++++++
clang/test/OpenMP/for_loop_auto.cpp | 2 +-
8 files changed, 44 insertions(+), 5 deletions(-)
create mode 100644 clang/test/CXX/dcl.decl/dcl.meaning/dcl.fct/p23.cpp
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index e158284aabeabc..32440ee64e3ebe 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -215,6 +215,8 @@ Bug Fixes to C++ Support
Fixes (`#68490 <https://github.com/llvm/llvm-project/issues/68490>`_)
- Fix a crash when trying to call a varargs function that also has an explicit object parameter.
Fixes (`#80971 ICE when explicit object parameter be a function parameter pack`)
+- Fixed a bug where abbreviated function templates would append their invented template parameters to
+ an empty template parameter lists.
Bug Fixes to AST Handling
^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/include/clang/AST/DeclTemplate.h b/clang/include/clang/AST/DeclTemplate.h
index baf71145d99dc6..e3b6a7efb1127a 100644
--- a/clang/include/clang/AST/DeclTemplate.h
+++ b/clang/include/clang/AST/DeclTemplate.h
@@ -134,6 +134,7 @@ class TemplateParameterList final
const_iterator end() const { return begin() + NumParams; }
unsigned size() const { return NumParams; }
+ bool empty() const { return NumParams == 0; }
ArrayRef<NamedDecl *> asArray() { return llvm::ArrayRef(begin(), end()); }
ArrayRef<const NamedDecl*> asArray() const {
diff --git a/clang/lib/AST/DeclPrinter.cpp b/clang/lib/AST/DeclPrinter.cpp
index 822ac12c4c7dd4..43d221968ea3fb 100644
--- a/clang/lib/AST/DeclPrinter.cpp
+++ b/clang/lib/AST/DeclPrinter.cpp
@@ -1215,6 +1215,10 @@ void DeclPrinter::printTemplateParameters(const TemplateParameterList *Params,
bool OmitTemplateKW) {
assert(Params);
+ // Don't print invented template parameter lists.
+ if (!Params->empty() && Params->getParam(0)->isImplicit())
+ return;
+
if (!OmitTemplateKW)
Out << "template ";
Out << '<';
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 18a5d93ab8e8c6..2c526cd0d0e675 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -9759,7 +9759,7 @@ Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC,
SmallVector<TemplateParameterList *, 4> TemplateParamLists;
llvm::append_range(TemplateParamLists, TemplateParamListsRef);
if (TemplateParameterList *Invented = D.getInventedTemplateParameterList()) {
- if (!TemplateParamLists.empty() &&
+ if (!TemplateParamLists.empty() && !TemplateParamLists.back()->empty() &&
Invented->getDepth() == TemplateParamLists.back()->getDepth())
TemplateParamLists.back() = Invented;
else
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index ab8a967b06a456..fea8c5036c80b1 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -19294,7 +19294,16 @@ void Sema::ActOnStartFunctionDeclarationDeclarator(
ExplicitLists, /*IsFriend=*/false, IsMemberSpecialization, IsInvalid,
/*SuppressDiagnostic=*/true);
}
- if (ExplicitParams) {
+ // C++23 [dcl.fct]p23:
+ // An abbreviated function template can have a template-head. The invented
+ // template-parameters are appended to the template-parameter-list after
+ // the explicitly declared template-parameters.
+ //
+ // A template-head must have one or more template-parameters (read:
+ // 'template<>' is *not* a template-head). Only append the invented
+ // template parameters if we matched the nested-name-specifier to a non-empty
+ // TemplateParameterList.
+ if (ExplicitParams && !ExplicitParams->empty()) {
Info.AutoTemplateParameterDepth = ExplicitParams->getDepth();
llvm::append_range(Info.TemplateParams, *ExplicitParams);
Info.NumExplicitTemplateParams = ExplicitParams->size();
diff --git a/clang/test/AST/ast-print-method-decl.cpp b/clang/test/AST/ast-print-method-decl.cpp
index 9f5d1126099442..75dea0cac16be1 100644
--- a/clang/test/AST/ast-print-method-decl.cpp
+++ b/clang/test/AST/ast-print-method-decl.cpp
@@ -32,8 +32,7 @@ struct DelegatingCtor2 {
// CHECK: struct DelegatingCtor3 {
struct DelegatingCtor3 {
- // FIXME: template <> should not be output
- // CHECK: template <> DelegatingCtor3(auto);
+ // CHECK: DelegatingCtor3(auto);
DelegatingCtor3(auto);
// FIXME: Implicitly specialized method should not be output
diff --git a/clang/test/CXX/dcl.decl/dcl.meaning/dcl.fct/p23.cpp b/clang/test/CXX/dcl.decl/dcl.meaning/dcl.fct/p23.cpp
new file mode 100644
index 00000000000000..469c4e091953c3
--- /dev/null
+++ b/clang/test/CXX/dcl.decl/dcl.meaning/dcl.fct/p23.cpp
@@ -0,0 +1,24 @@
+// RUN: %clang_cc1 -std=c++20 -pedantic-errors -verify %s
+
+// FIXME: This should be an error with -pedantic-errors.
+template<> // expected-warning {{extraneous template parameter list in template specialization}}
+void f(auto);
+
+template<typename>
+void f(auto);
+
+template<typename T>
+struct A {
+ void g(auto);
+};
+
+template<typename T>
+void A<T>::g(auto) { }
+
+template<>
+void A<int>::g(auto) { }
+
+// FIXME: This should be an error with -pedantic-errors.
+template<>
+template<> // expected-warning {{extraneous template parameter list in template specialization}}
+void A<long>::g(auto) { }
diff --git a/clang/test/OpenMP/for_loop_auto.cpp b/clang/test/OpenMP/for_loop_auto.cpp
index b2c5540a7785ab..4467de6bba18dc 100644
--- a/clang/test/OpenMP/for_loop_auto.cpp
+++ b/clang/test/OpenMP/for_loop_auto.cpp
@@ -10,7 +10,7 @@
#ifndef HEADER
#define HEADER
-// CHECK: template <> void do_loop(const auto &v) {
+// CHECK: void do_loop(const auto &v) {
// CHECK-NEXT: #pragma omp parallel for
// CHECK-NEXT: for (const auto &i : v)
// CHECK-NEXT: ;
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