Thanks for the suggestion. I installed the attached more-elaborate
patch, which also affects autom4te and autoscan.From 7feeafdf2f3e5bfe670b40994092d2e8ec5a536c Mon Sep 17 00:00:00 2001
From: Paul Eggert <egg...@cs.ucla.edu>
Date: Sat, 15 Jun 2024 08:24:05 -0700
Subject: [PATCH] Process C23 #elifdef and #elifndef
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Inspired by Collin Funk’s suggestion in:
https://lists.gnu.org/r/autoconf-patches/2024-06/msg00000.html
* bin/autom4te.in (handle_output):
* bin/autoscan.in, bin/ifnames.in (scan_c_file):
Also recognize #elifdef and #elifndef.
* tests/tools.at (ifnames): Test it for ifnames.
---
NEWS | 6 ++++++
bin/autom4te.in | 4 ++--
bin/autoscan.in | 2 +-
bin/ifnames.in | 9 +++++----
doc/autoconf.texi | 5 +++--
tests/tools.at | 4 ++++
6 files changed, 21 insertions(+), 9 deletions(-)
diff --git a/NEWS b/NEWS
index 521bbd3a..bca11391 100644
--- a/NEWS
+++ b/NEWS
@@ -22,6 +22,12 @@ GNU Autoconf NEWS - User visible changes.
This reverts to Autoconf 2.69 behavior, and also fixes a bug where
AC_PROG_CXX rejected C++20 compilers.
+** New features
+
+*** Programs now recognize #elifdef and #elifndef.
+ The autom4te, autoscan and ifnames programs now recognize the two
+ preprocessor directives, which were introduced in C23 and C++23.
+
* Noteworthy changes in release 2.72 (2023-12-22) [release]
** Backward incompatibilities
diff --git a/bin/autom4te.in b/bin/autom4te.in
index e9fa1886..48377cb9 100644
--- a/bin/autom4te.in
+++ b/bin/autom4te.in
@@ -636,7 +636,7 @@ sub handle_output ($$)
# Don't complain in comments. Well, until we have something
# better, don't consider '#include' etc. are comments.
s/\#.*//
- unless /^\#\s*(if|include|endif|ifdef|ifndef|define)\b/;
+ unless /^\#\s*(include|endif|(el)?if(n?def)?|define)\b/;
foreach (split (/\W+/))
{
$prohibited{$_} = $.
@@ -673,7 +673,7 @@ sub handle_output ($$)
# Don't complain in comments. Well, until we have something
# better, don't consider '#include' etc. to be comments.
s/\#.*//
- unless /^\#(if|include|endif|ifdef|ifndef|define)\b/;
+ unless /^\#(include|endif|(el)?if(n?def)?|define)\b/;
# Complain once per word, but possibly several times per line.
while (/$prohibited/)
diff --git a/bin/autoscan.in b/bin/autoscan.in
index 5072f80c..542865a9 100644
--- a/bin/autoscan.in
+++ b/bin/autoscan.in
@@ -276,7 +276,7 @@ sub scan_c_file ($)
{
used ('header', $1);
}
- if (s/^(if|ifdef|ifndef|elif)\s+//)
+ if (s/^(el)?if(n?def)?\s+//)
{
foreach my $word (split (/\W+/))
{
diff --git a/bin/ifnames.in b/bin/ifnames.in
index c0c5f611..59a3d131 100644
--- a/bin/ifnames.in
+++ b/bin/ifnames.in
@@ -55,9 +55,10 @@ $help = "Usage: $0 [OPTION]... [FILE]...
Scan all of the C source FILES (or the standard input, if none are
given) and write to the standard output a sorted list of all the
-identifiers that appear in those files in '#if', '#elif', '#ifdef', or
-'#ifndef' directives. Print each identifier on a line, followed by a
-space-separated list of the files in which that identifier occurs.
+identifiers that appear in those files in '#if', '#ifdef', '#ifndef',
+'#elif', '#elifdef', or '#elifndef' directives. Print each identifier
+on a line, followed by a space-separated list of the files in which
+that identifier occurs.
-h, --help print this help, then exit
-V, --version print version number, then exit
@@ -109,7 +110,7 @@ sub scan_file ($)
while (s/\\$//);
# Preprocessor directives.
- if (s/^\s*\#\s*(if|ifdef|ifndef|elif)\s+//)
+ if (s/^\s*\#\s*(el)?if(n?def)?\s+//)
{
# Remove comments. Not perfect, but close enough.
s(/\*.*?\*/)();
diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 9c05ecee..832858cf 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -1478,8 +1478,9 @@ Invocation}).
@command{ifnames} scans all of the C source files named on the command line
(or the standard input, if none are given) and writes to the standard
output a sorted list of all the identifiers that appear in those files
-in @code{#if}, @code{#elif}, @code{#ifdef}, or @code{#ifndef}
-directives. It prints each identifier on a line, followed by a
+in @code{#if}, @code{#ifdef}, @code{#ifndef}, @code{#elif},
+@code{#elifdef}, or @code{#elifndef} directives.
+It prints each identifier on a line, followed by a
space-separated list of the files in which that identifier occurs.
@noindent
diff --git a/tests/tools.at b/tests/tools.at
index 37fe1466..867ecd68 100644
--- a/tests/tools.at
+++ b/tests/tools.at
@@ -732,6 +732,8 @@ LINE2
AT_DATA([iftest2.c],
[[#ifdef IFTEST2
+#elifdef IFTEST3
+#elifndef IFTEST4
#if VAL1
]])
@@ -741,6 +743,8 @@ DEF2 iftest1.c
DEF3 iftest1.c
DEF4 iftest1.c
IFTEST2 iftest2.c
+IFTEST3 iftest2.c
+IFTEST4 iftest2.c
LINE1 iftest1.c
LINE2 iftest1.c
SPACES iftest1.c
--
2.43.0
