[clang] [clang-tools-extra] Suppress pedantic diagnostic for a file not ending in EOL (PR #131794)
Aaron Ballman via cfe-commits
cfe-commits at lists.llvm.org
Tue Mar 18 06:17:41 PDT 2025
https://github.com/AaronBallman updated https://github.com/llvm/llvm-project/pull/131794
>From 22c4b9d7808df33d3e6a31b3456cd8b2e8a95bfa Mon Sep 17 00:00:00 2001
From: Aaron Ballman <aaron at aaronballman.com>
Date: Tue, 18 Mar 2025 08:34:18 -0400
Subject: [PATCH 1/2] Suppress pedantic diagnostic for a file not ending in EOL
WG14 added N3411 to the list of papers which apply to older versions of
C, and WG21 adopted CWG787 as a Defect Report in C++11. So we no longer
should be issuing a pedantic diagnostic about a file which does not end
with a newline character.
We do, however, continue to support -Wnewline-eof as an opt-in
diagnostic.
---
clang-tools-extra/clangd/Preamble.cpp | 1 -
clang/docs/ReleaseNotes.rst | 5 ++++-
.../include/clang/Basic/DiagnosticLexKinds.td | 2 --
clang/lib/Lex/Lexer.cpp | 18 ++++++------------
clang/test/C/C2y/n3411.c | 3 ++-
clang/test/Lexer/newline-eof.c | 15 ++++++++++-----
6 files changed, 22 insertions(+), 22 deletions(-)
diff --git a/clang-tools-extra/clangd/Preamble.cpp b/clang-tools-extra/clangd/Preamble.cpp
index b634981bb46bd..233d827e6ed7b 100644
--- a/clang-tools-extra/clangd/Preamble.cpp
+++ b/clang-tools-extra/clangd/Preamble.cpp
@@ -628,7 +628,6 @@ buildPreamble(PathRef FileName, CompilerInvocation CI,
switch (Info.getID()) {
case diag::warn_no_newline_eof:
case diag::warn_cxx98_compat_no_newline_eof:
- case diag::ext_no_newline_eof:
// If the preamble doesn't span the whole file, drop the no newline at
// eof warnings.
return Bounds.Size != ContentsBuffer->getBufferSize()
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 0adbc19f40096..71d7f9f85e739 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -128,7 +128,10 @@ C2y Feature Support
also removes UB with code like ``(void)(void)1;``.
- Implemented `WG14 N3411 <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3411.pdf>`_
which allows a source file to not end with a newline character. This is still
- reported as a conforming extension in earlier language modes.
+ reported as a conforming extension in earlier language modes. Note,
+ ``-pedantic`` will no longer diagnose this in either C or C++ modes as an
+ extension. This feature was adopted as applying to obsolete versions of C in
+ WG14 and as a defect report in WG21 (CWG787).
- Implemented `WG14 N3353 <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3353.htm>_`
which adds the new ``0o`` and ``0O`` ocal literal prefixes and deprecates
octal literals other than ``0`` which do not start with the new prefix. This
diff --git a/clang/include/clang/Basic/DiagnosticLexKinds.td b/clang/include/clang/Basic/DiagnosticLexKinds.td
index bdb7e9350b5f7..cf226856864c0 100644
--- a/clang/include/clang/Basic/DiagnosticLexKinds.td
+++ b/clang/include/clang/Basic/DiagnosticLexKinds.td
@@ -52,8 +52,6 @@ def ext_multi_line_line_comment : Extension<"multi-line // comment">,
def ext_line_comment : Extension<
"// comments are not allowed in this language">,
InGroup<Comment>;
-def ext_no_newline_eof : Extension<"no newline at end of file">,
- InGroup<NewlineEOF>;
def warn_no_newline_eof : Warning<"no newline at end of file">,
InGroup<NewlineEOF>, DefaultIgnore;
diff --git a/clang/lib/Lex/Lexer.cpp b/clang/lib/Lex/Lexer.cpp
index 96d5d4f440768..fcc53f91b5728 100644
--- a/clang/lib/Lex/Lexer.cpp
+++ b/clang/lib/Lex/Lexer.cpp
@@ -3194,18 +3194,12 @@ bool Lexer::LexEndOfFile(Token &Result, const char *CurPtr) {
SourceLocation EndLoc = getSourceLocation(BufferEnd);
unsigned DiagID = diag::warn_no_newline_eof;
- if (LangOpts.CPlusPlus11) {
- // C++11 [lex.phases] 2.2 p2
- // Prefer the C++98 pedantic compatibility warning over the generic,
- // non-extension, user-requested "missing newline at EOF" warning.
- if (!Diags.isIgnored(diag::warn_cxx98_compat_no_newline_eof, EndLoc))
- DiagID = diag::warn_cxx98_compat_no_newline_eof;
- } else {
- // This is conforming in C2y, but is an extension in earlier language
- // modes.
- if (!LangOpts.C2y)
- DiagID = diag::ext_no_newline_eof;
- }
+ // C++11 [lex.phases] 2.2 p2
+ // Prefer the C++98 pedantic compatibility warning over the generic,
+ // non-extension, user-requested "missing newline at EOF" warning.
+ if (LangOpts.CPlusPlus11 &&
+ !Diags.isIgnored(diag::warn_cxx98_compat_no_newline_eof, EndLoc))
+ DiagID = diag::warn_cxx98_compat_no_newline_eof;
Diag(BufferEnd, DiagID) << FixItHint::CreateInsertion(EndLoc, "\n");
}
diff --git a/clang/test/C/C2y/n3411.c b/clang/test/C/C2y/n3411.c
index 934a7c70fa67e..0fea769e30460 100644
--- a/clang/test/C/C2y/n3411.c
+++ b/clang/test/C/C2y/n3411.c
@@ -1,7 +1,8 @@
// RUN: %clang_cc1 -verify=good -std=c2y -Wall -pedantic %s
// RUN: %clang_cc1 -verify -Wnewline-eof -std=c2y -Wall -pedantic %s
-// RUN: %clang_cc1 -verify -std=c23 -Wall -pedantic %s
+// RUN: %clang_cc1 -verify=good -std=c23 -Wall -pedantic %s
// RUN: %clang_cc1 -verify=good -std=c23 %s
+// RUN: %clang_cc1 -verify -Wnewline-eof -std=c23 %s
/* WG14 N3411: Yes
* Slay Some Earthly Demons XII
diff --git a/clang/test/Lexer/newline-eof.c b/clang/test/Lexer/newline-eof.c
index 9f5033384e16f..22245ac357efc 100644
--- a/clang/test/Lexer/newline-eof.c
+++ b/clang/test/Lexer/newline-eof.c
@@ -1,11 +1,16 @@
-// RUN: %clang_cc1 -fsyntax-only -Wnewline-eof -verify %s
-// RUN: %clang_cc1 -fsyntax-only -pedantic -verify %s
-// RUN: %clang_cc1 -fsyntax-only -x c++ -std=c++03 -pedantic -verify %s
-// RUN: %clang_cc1 -fsyntax-only -Wnewline-eof %s 2>&1 | FileCheck %s
+// Allowing a file to end without a newline was adopted as a Defect Report in
+// WG21 (CWG787) and in WG14 (added to the list of changes which apply to
+// earlier revisions of C in C2y). So it should not issue a pedantic diagnostic
+// in any language mode.
-// In C++11 mode, this is allowed, so don't warn in pedantic mode.
+// RUN: %clang_cc1 -fsyntax-only -Wnewline-eof -verify %s
+// RUN: %clang_cc1 -fsyntax-only -pedantic -verify=good %s
+// RUN: %clang_cc1 -fsyntax-only -std=c89 -pedantic -Wno-comment -verify=good %s
+// RUN: %clang_cc1 -fsyntax-only -x c++ -std=c++03 -pedantic -verify=good %s
// RUN: %clang_cc1 -fsyntax-only -x c++ -std=c++11 -Wnewline-eof -verify %s
// RUN: %clang_cc1 -fsyntax-only -x c++ -std=c++11 -Werror -pedantic %s
+// RUN: %clang_cc1 -fsyntax-only -Wnewline-eof %s 2>&1 | FileCheck %s
+// good-no-diagnostics
// Make sure the diagnostic shows up properly at the end of the last line.
// CHECK: newline-eof.c:[[@LINE+3]]:67
>From c7568b7ccf3932f9420d123954e2db9a97908c05 Mon Sep 17 00:00:00 2001
From: Aaron Ballman <aaron at aaronballman.com>
Date: Tue, 18 Mar 2025 09:16:43 -0400
Subject: [PATCH 2/2] Add C++ DR test
Note: I wasn't able to run the python script to regenerate the
cxx_dr_status.html page due to encoding errors, so that still needs to
be run.
---
clang/test/CXX/drs/cwg787.cpp | 13 +++++++++++++
1 file changed, 13 insertions(+)
create mode 100644 clang/test/CXX/drs/cwg787.cpp
diff --git a/clang/test/CXX/drs/cwg787.cpp b/clang/test/CXX/drs/cwg787.cpp
new file mode 100644
index 0000000000000..15f6bdebba9ac
--- /dev/null
+++ b/clang/test/CXX/drs/cwg787.cpp
@@ -0,0 +1,13 @@
+// RUN: %clang_cc1 -triple %itanium_abi_triple -std=c++98 %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -triple %itanium_abi_triple -std=c++11 %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -triple %itanium_abi_triple -std=c++14 %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -triple %itanium_abi_triple -std=c++17 %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -triple %itanium_abi_triple -std=c++20 %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -triple %itanium_abi_triple -std=c++23 %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -triple %itanium_abi_triple -std=c++2c %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// expected-no-diagnostics
+
+// This file intentionally does not end with a newline. CWG787 made this
+// well-defined behavior.
+
+// cwg787: 3.0
\ No newline at end of file
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