simplifying the creation of ChangeLog entries

[Bruno Haible]

When creating a ChangeLog entry for *.m4 files, we should mention the Autoconf
macro name. git's default heuristic is to look at the previous line that
starts with a non-whitespace character. Unfortunately, in our *.m4 files, we
have C code and changequotes command frequently indented at column 0; this
kills the heuristic. This patch adds another heuristic, suitable for *.m4 files.


diff --git a/.gitattributes b/.gitattributes
index 35a14df8a2..bad5997b57 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -4,3 +4,7 @@ ChangeLog       merge=merge-changelog
 # Run this to make 'git diff' on texinfo files give nicer hunk context:
 #   git config diff.texinfo.funcname '^@node[   ][      ]*\\([^,][^,]*\\)'
 *.texi* diff=texinfo
+
+# Run this to make 'git diff' on .m4 files give nicer hunk context:
+#   git config diff.m4.xfuncname '^((AC_DEFUN|m4_define)[^,)]*)'
+*.m4   diff=m4