Re: add --match argument to git-version-gen

[Andy Wingo]

On Fri 06 Jul 2012 17:45, Jim Meyering <address@hidden> writes:

> How about writing a function -- with description similar to the comments
> you've added below -- and doing something like the following?
> Then we should be able to avoid that duplication.
>
>     elif test "`git log -1 --pretty=format:x . 2>&1`" = x \
>    -    && v=`git describe --abbrev=4 --match="$prefix*" HEAD 2>/dev/null \
>    -          || git describe --abbrev=4 HEAD 2>/dev/null` \
>    +    && v=`git_desc "$prefix" "$match"` \
>         ...

Good suggestion.  Attached.

>From f93e662664c1eac104e1144bea94d9386ffc8ab5 Mon Sep 17 00:00:00 2001
From: Andy Wingo <address@hidden>
Date: Fri, 6 Jul 2012 17:27:37 +0200
Subject: [PATCH] git-version-gen: add --match argument.

* build-aux/git-version-gen (Options): Add --match argument.
  (match):
  (tag_sed_script):
  (tarball_version_file): Protect against ambient values of these
  variables.
  (git_describe, massage_git_version): New helper functions.  Require a
  match in the --match case, and otherwise have our previous behavior.

Using --match can prevent a merge from e.g. a version 2 branch to a 3
branch from causing the 3 branch to show a 2 version, if the 2 version
tagged more recently than the 3 version.
---
 build-aux/git-version-gen |   73 ++++++++++++++++++++++++++++++++-------------
 1 file changed, 52 insertions(+), 21 deletions(-)

diff --git a/build-aux/git-version-gen b/build-aux/git-version-gen
index 0fa9063..ca98f4a 100755
--- a/build-aux/git-version-gen
+++ b/build-aux/git-version-gen
@@ -1,6 +1,6 @@
 #!/bin/sh
 # Print a version string.
-scriptversion=2012-03-18.17; # UTC
+scriptversion=2012-07-06.17; # UTC
 
 # Copyright (C) 2007-2012 Free Software Foundation, Inc.
 #
@@ -85,20 +85,27 @@ Print a version string.
 
 Options:
 
-   --prefix           prefix of git tags (default 'v')
+   --prefix     prefix of git tags to strip from version (default 'v')
+   --match      pattern for git tags to match
 
-   --help             display this help and exit
-   --version          output version information and exit
+   --help       display this help and exit
+   --version    output version information and exit
 
-Running without arguments will suffice in most cases."
+Running without arguments will suffice in most cases.  If no --match
+argument is given, try to match tags that begin with the --prefix,
+falling back to the first tag that git-describe finds."
 
 prefix=v
+match=
+tag_sed_script=
+tarball_version_file=
 
 while test $# -gt 0; do
   case $1 in
     --help) echo "$usage"; exit 0;;
     --version) echo "$version"; exit 0;;
     --prefix) shift; prefix="$1";;
+    --match) shift; match="$1";;
     -*)
       echo "$0: Unknown option '$1'." >&2
       echo "$0: Try '--help' for more information." >&2
@@ -144,21 +151,8 @@ then
         && echo "$0: WARNING: $tarball_version_file is missing or damaged" 1>&2
 fi
 
-if test -n "$v"
-then
-    : # use $v
-# Otherwise, if there is at least one git commit involving the working
-# directory, and "git describe" output looks sensible, use that to
-# derive a version string.
-elif test "`git log -1 --pretty=format:x . 2>&1`" = x \
-    && v=`git describe --abbrev=4 --match="$prefix*" HEAD 2>/dev/null \
-          || git describe --abbrev=4 HEAD 2>/dev/null` \
-    && v=`printf '%s\n' "$v" | sed "$tag_sed_script"` \
-    && case $v in
-         $prefix[0-9]*) ;;
-         *) (exit 1) ;;
-       esac
-then
+function massage_git_version() {
+    local v=$1
     # Is this a new git that lists number of commits since the last
     # tag or the previous older version that did not?
     #   Newer: v6.10-77-g0f8faeb
@@ -182,7 +176,44 @@ then
 
     # Change the first '-' to a '.', so version-comparing tools work properly.
     # Remove the "g" in git describe's output string, to save a byte.
-    v=`echo "$v" | sed 's/-/./;s/\(.*\)-g/\1-/'`;
+    echo "$v" | sed 's/-/./;s/\(.*\)-g/\1-/'
+}
+
+function git_describe() {
+    local prefix=$1
+    local match=$2
+    local v
+
+    # Make sure this working directory has commits.
+    test "`git log -1 --pretty=format:x . 2>&1`" = x || exit 1
+
+    # If the user specified --match, look for a matching tag.
+    # Otherwise, look for a tag starting with --prefix, or the first tag
+    # we find.
+    if test -n "$match"
+    then
+        v=`git describe --abbrev=4 --match="$match" HEAD 2>/dev/null` || exit 1
+    else
+        v=`git describe --abbrev=4 --match="$prefix*" HEAD 2>/dev/null \
+            || git describe --abbrev=4 HEAD 2>/dev/null` || exit 1
+    fi
+
+    v=`printf '%s\n' "$v" | sed "$tag_sed_script"` || exit 1
+    case $v in
+        $prefix[0-9]*)
+            massage_git_version "$v"
+            ;;
+        *) 
+            exit 1
+            ;;
+    esac
+}
+
+if test -n "$v"
+then
+    : # use $v
+elif v=`git_describe "$prefix" "$match"`
+then
     v_from_git=1
 else
     v=UNKNOWN
-- 
1.7.10

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