[clang] [clang][Sema] Emit more specific diagnostic for auto in lambda before C++14 (#46059) (PR #68540)
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Thu May 16 05:44:43 PDT 2024
https://github.com/cor3ntin updated https://github.com/llvm/llvm-project/pull/68540
>From 613ea6809b478ff7391614b24ec177fc19339cdd Mon Sep 17 00:00:00 2001
From: Leonardo Duarte <weltschildkroete at gmail.com>
Date: Sun, 8 Oct 2023 12:59:15 +0200
Subject: [PATCH 1/6] [clang][Sema] Emit more specific diagnostic for auto in
lambda before C++14 (#46059)
Namely, we specify that `auto` in a lambda parameter is a C++14
extension in the error message, which now reads:
`'auto' not allowed in lambda parameter until C++14`
This does not change the behavior for `decltype(auto)` and `__auto_type`
though.
The relevant change to `SemaType.cpp` is the addition of a branch that
sets `Error = 24`, whilst the bulk of the change comes from formatting.
---
clang/include/clang/Basic/DiagnosticSemaKinds.td | 2 +-
clang/lib/Sema/SemaType.cpp | 7 +++++--
clang/test/SemaCXX/auto-cxx0x.cpp | 4 ++--
3 files changed, 8 insertions(+), 5 deletions(-)
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index c1a6e3831127e..815f78675c72e 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -2393,7 +2393,7 @@ def err_auto_not_allowed : Error<
"|in type allocated by 'new'|in K&R-style function parameter"
"|in template parameter|in friend declaration|in function prototype that is "
"not a function declaration|in requires expression parameter"
- "|in array declaration}1">;
+ "|in array declaration|in lambda parameter until C++14}1">;
def err_dependent_deduced_tst : Error<
"typename specifier refers to "
"%select{class template|function template|variable template|alias template|"
diff --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
index 068971f8130a4..52a8161797e15 100644
--- a/clang/lib/Sema/SemaType.cpp
+++ b/clang/lib/Sema/SemaType.cpp
@@ -3605,8 +3605,11 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
Info = &SemaRef.InventedParameterInfos.back();
} else {
// In C++14, generic lambdas allow 'auto' in their parameters.
- if (!SemaRef.getLangOpts().CPlusPlus14 || !Auto ||
- Auto->getKeyword() != AutoTypeKeyword::Auto) {
+ if (!SemaRef.getLangOpts().CPlusPlus14 && Auto &&
+ Auto->getKeyword() == AutoTypeKeyword::Auto) {
+ Error = 24;
+ break;
+ } else if (!Auto || Auto->getKeyword() != AutoTypeKeyword::Auto) {
Error = 16;
break;
}
diff --git a/clang/test/SemaCXX/auto-cxx0x.cpp b/clang/test/SemaCXX/auto-cxx0x.cpp
index b4da3f9330c10..65398de28e10c 100644
--- a/clang/test/SemaCXX/auto-cxx0x.cpp
+++ b/clang/test/SemaCXX/auto-cxx0x.cpp
@@ -12,7 +12,7 @@ thread_local auto x; // expected-error {{requires an initializer}}
void g() {
[](auto){}(0);
#if __cplusplus == 201103L
- // expected-error at -2 {{'auto' not allowed in lambda parameter}}
+ // expected-error at -2 {{'auto' not allowed in lambda parameter until C++14}}
#endif
}
@@ -20,6 +20,6 @@ void rdar47689465() {
int x = 0;
[](auto __attribute__((noderef)) *){}(&x);
#if __cplusplus == 201103L
- // expected-error at -2 {{'auto' not allowed in lambda parameter}}
+ // expected-error at -2 {{'auto' not allowed in lambda parameter until C++14}}
#endif
}
>From b884f2b79d57343dea6e7f9b16dfc96984ec1f5b Mon Sep 17 00:00:00 2001
From: Leonardo Duarte <weltschildkroete at gmail.com>
Date: Tue, 10 Oct 2023 22:52:54 +0200
Subject: [PATCH 2/6] Slightly change wording in diagnostic
---
clang/include/clang/Basic/DiagnosticSemaKinds.td | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 815f78675c72e..02644a84b4f4e 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -2393,7 +2393,7 @@ def err_auto_not_allowed : Error<
"|in type allocated by 'new'|in K&R-style function parameter"
"|in template parameter|in friend declaration|in function prototype that is "
"not a function declaration|in requires expression parameter"
- "|in array declaration|in lambda parameter until C++14}1">;
+ "|in array declaration|in lambda parameter before C++14}1">;
def err_dependent_deduced_tst : Error<
"typename specifier refers to "
"%select{class template|function template|variable template|alias template|"
>From 99bc3b6cb8d1a812b6dcd573261a77a2d50a79e2 Mon Sep 17 00:00:00 2001
From: Leonardo Duarte <weltschildkroete at gmail.com>
Date: Tue, 10 Oct 2023 23:09:07 +0200
Subject: [PATCH 3/6] Add release note
---
clang/docs/ReleaseNotes.rst | 3 +++
1 file changed, 3 insertions(+)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 2d918967e7f0b..41d83791cb5f2 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -301,6 +301,9 @@ Improvements to Clang's diagnostics
- Clang now always diagnoses when using non-standard layout types in ``offsetof`` .
(`#64619: <https://github.com/llvm/llvm-project/issues/64619>`_)
+- Clang now specifies that using ``auto`` in a lambda parameter is a C++14 extension when
+ appropriate. (`#46059: <https://github.com/llvm/llvm-project/issues/46059>`_).
+
Bug Fixes in This Version
-------------------------
- Fixed an issue where a class template specialization whose declaration is
>From b620007bc17c46468f0046ca135163cdaa519783 Mon Sep 17 00:00:00 2001
From: Leonardo Duarte <weltschildkroete at gmail.com>
Date: Tue, 10 Oct 2023 23:17:41 +0200
Subject: [PATCH 4/6] Update wording on tests
---
clang/test/SemaCXX/auto-cxx0x.cpp | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/clang/test/SemaCXX/auto-cxx0x.cpp b/clang/test/SemaCXX/auto-cxx0x.cpp
index 65398de28e10c..07687b6066790 100644
--- a/clang/test/SemaCXX/auto-cxx0x.cpp
+++ b/clang/test/SemaCXX/auto-cxx0x.cpp
@@ -12,7 +12,7 @@ thread_local auto x; // expected-error {{requires an initializer}}
void g() {
[](auto){}(0);
#if __cplusplus == 201103L
- // expected-error at -2 {{'auto' not allowed in lambda parameter until C++14}}
+ // expected-error at -2 {{'auto' not allowed in lambda parameter before C++14}}
#endif
}
@@ -20,6 +20,6 @@ void rdar47689465() {
int x = 0;
[](auto __attribute__((noderef)) *){}(&x);
#if __cplusplus == 201103L
- // expected-error at -2 {{'auto' not allowed in lambda parameter until C++14}}
+ // expected-error at -2 {{'auto' not allowed in lambda parameter before C++14}}
#endif
}
>From 031e76900f6e63c97ed8666066ff98d967305af4 Mon Sep 17 00:00:00 2001
From: Leonardo Duarte <weltschildkroete at gmail.com>
Date: Wed, 11 Oct 2023 22:50:59 +0200
Subject: [PATCH 5/6] Add comments for which diagnostic to emit
---
clang/lib/Sema/SemaType.cpp | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
index 52a8161797e15..da759ba340c72 100644
--- a/clang/lib/Sema/SemaType.cpp
+++ b/clang/lib/Sema/SemaType.cpp
@@ -3607,10 +3607,10 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
// In C++14, generic lambdas allow 'auto' in their parameters.
if (!SemaRef.getLangOpts().CPlusPlus14 && Auto &&
Auto->getKeyword() == AutoTypeKeyword::Auto) {
- Error = 24;
+ Error = 24; // auto not allowed in lambda parameter (before C++14)
break;
} else if (!Auto || Auto->getKeyword() != AutoTypeKeyword::Auto) {
- Error = 16;
+ Error = 16; // __auto_type or decltype(auto) not allowed in lambda parameter
break;
}
Info = SemaRef.getCurLambda();
>From 86e53efbed1387c9743e3ec4d8c074119821f917 Mon Sep 17 00:00:00 2001
From: Leonardo Duarte <weltschildkroete at gmail.com>
Date: Wed, 11 Oct 2023 23:15:16 +0200
Subject: [PATCH 6/6] Apply clang-format
---
clang/lib/Sema/SemaType.cpp | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
index da759ba340c72..4f54645a9c148 100644
--- a/clang/lib/Sema/SemaType.cpp
+++ b/clang/lib/Sema/SemaType.cpp
@@ -3610,7 +3610,8 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
Error = 24; // auto not allowed in lambda parameter (before C++14)
break;
} else if (!Auto || Auto->getKeyword() != AutoTypeKeyword::Auto) {
- Error = 16; // __auto_type or decltype(auto) not allowed in lambda parameter
+ Error = 16; // __auto_type or decltype(auto) not allowed in lambda
+ // parameter
break;
}
Info = SemaRef.getCurLambda();
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