Improve C and Elisp Git diff hunk headers

For discussion, see the following threads:
https://lists.gnu.org/archive/html/emacs-devel/2019-03/msg00457.html
https://lists.gnu.org/archive/html/emacs-devel/2019-05/msg00369.html

* autogen.sh: Extend the built-in Git xfuncname pattern 'cpp' to
match preprocessor and DEFUN macros, and the 'elisp' pattern to
match cl-lib and other top-level defuns.

diff --git a/autogen.sh b/autogen.sh
index f390b1a777cf20570e4b26833e69b445454eea0c..d0f60dc68afb891ad8624bcfcbc46cf6c8817737 100755 (executable)
--- a/autogen.sh
+++ b/autogen.sh
@@ -315,8 +315,16 @@ git_config transfer.fsckObjects true
 
 # Configure 'git diff' hunk header format.
 
+# This xfuncname is based on Git's built-in 'cpp' pattern.
+# The first line rejects jump targets and access declarations.
+# The second line matches top-level functions and methods.
+# The third line matches preprocessor and DEFUN macros.
+git_config diff.cpp.xfuncname \
+'!^[ \t]*[A-Za-z_][A-Za-z_0-9]*:[[:space:]]*($|/[/*])
+^((::[[:space:]]*)?[A-Za-z_][A-Za-z_0-9]*[[:space:]]*\(.*)$
+^((#define[[:space:]]|DEFUN).*)$'
 git_config diff.elisp.xfuncname \
-          '^\(def[^[:space:]]+[[:space:]]+([^()[:space:]]+)'
+           '^\([^[:space:]]*def[^[:space:]]+[[:space:]]+([^()[:space:]]+)'
 git_config 'diff.m4.xfuncname' '^((m4_)?define|A._DEFUN(_ONCE)?)\([^),]*'
 git_config 'diff.make.xfuncname' \
           '^([$.[:alnum:]_].*:|[[:alnum:]_]+[[:space:]]*([*:+]?[:?]?|!?)=|define .*)'