From 56766ede64d4abfaa7c694122e7bb601a427736d Mon Sep 17 00:00:00 2001
From: Jan Engelhardt <jengelh@inai.de>
Date: Wed, 9 Aug 2023 18:07:00 -0700
Subject: [PATCH] automake: portability warning for dollar-escaped dollar
 signs.

This bug and fix was posted at
https://lists.gnu.org/archive/html/automake/2023-08/msg00003.html.

* lib/Automake/Variable.pm (scan_variable_expansions): rewrite
scan_variable_expansions regex to handle dollar-escaped dollar signs.
* t/dollarvar2.sh: test it.
---
 lib/Automake/Variable.pm | 5 +++--
 t/dollarvar2.sh          | 9 +++++++++
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/lib/Automake/Variable.pm b/lib/Automake/Variable.pm
index 8bafc8e3a..82215b511 100644
--- a/lib/Automake/Variable.pm
+++ b/lib/Automake/Variable.pm
@@ -748,9 +748,10 @@ sub scan_variable_expansions ($)
   $text =~ s/#.*$//;
 
   # Record each use of ${stuff} or $(stuff) that does not follow a $.
-  while ($text =~ /(?<!\$)\$(?:\{([^\}]*)\}|\(([^\)]*)\))/g)
+  while ($text =~ m{\$(?:\{([^\}]*)\}|\(([^\)]*)\)|(\$))}g)
     {
-      my $var = $1 || $2;
+      my $var = $1 || $2 || $3;
+      next if $var eq '$';
       # The occurrence may look like $(string1[:subst1=[subst2]]) but
       # we want only 'string1'.
       $var =~ s/:[^:=]*=[^=]*$//;
diff --git a/t/dollarvar2.sh b/t/dollarvar2.sh
index 5f794a61f..4fc99fd33 100644
--- a/t/dollarvar2.sh
+++ b/t/dollarvar2.sh
@@ -83,4 +83,13 @@ AUTOMAKE_fails -Wno-portability -Wportability-recursive
 grep 'var-with-dash' stderr && exit 1
 grep 'recursive variable expansion' stderr
 
+#
+# Ensure that GNU make function calls give a portability warning
+# under a certain condition that older automake missed.
+#
+cat >Makefile.am <<'EOF'
+x = $$$(y z)
+EOF
+AUTOMAKE_fails -Wportability
+
 :
-- 
2.47.2