FAILED: patch "[PATCH] scripts/tags.sh: fix incompatibility with PCRE2" failed to apply to 4.19-stable tree

The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

Possible dependencies:

6ec363fc6142 ("scripts/tags.sh: fix incompatibility with PCRE2") 7394d2ebb651 ("scripts/tags.sh: Invoke 'realpath' via 'xargs'") 162343a876f1 ("scripts/tags.sh: exclude tools directory from tags generation") 4f491bb6ea2a ("scripts/tags.sh: collect compiled source precisely")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 6ec363fc6142226b9ab5a6528f65333d729d2b6b Mon Sep 17 00:00:00 2001
From: Carlos Llamas <[email protected]>
Date: Wed, 15 Feb 2023 18:38:50 +0000
Subject: [PATCH] scripts/tags.sh: fix incompatibility with PCRE2

Starting with release 10.38 PCRE2 drops default support for using \K in lookaround patterns as described in [1]. Unfortunately, scripts/tags.sh relies on such functionality to collect all_compiled_soures() leading to the following error:

  $ make COMPILED_SOURCE=1 tags
    GEN     tags
  grep: \K is not allowed in lookarounds (but see PCRE2_EXTRA_ALLOW_LOOKAROUND_BSK)

The usage of \K for this pattern was introduced in commit 4f491bb6ea2a ("scripts/tags.sh: collect compiled source precisely") which speeds up the generation of tags significantly.

In order to fix this issue without compromising the performance we can switch over to an equivalent sed expression. The same matching pattern is preserved here except \K is replaced with a backreference \1.

[1] https://www.pcre.org/current/doc/html/pcre2syntax.html#SEC11

index 1ad45f17179a..6b9001853890 100755
@@ -98,7 +98,7 @@ all_compiled_sources()
 	{
 		echo include/generated/autoconf.h
 		find $ignore -name "*.cmd" -exec \
-			grep -Poh '(?(?=^source_.* \K).*|(?=^  \K\S).*(?= \\))' {} \+ |
+			sed -n -E 's/^source_.* (.*)/\1/p; s/^  (\S.*) \\/\1/p' {} \+ |
 		awk '!a[$0]++'
 	} | xargs realpath -esq $([ -z "$KBUILD_ABS_SRCTREE" ] && echo --relative-to=.) |
 	sort -u