Add helper script for a smart rebuild.

packaging/patch-update

@@ -127,18 +127,27 @@ def update_patch(patch):
 
     s = cmd_run(['git', 'merge', based_on])
     ok = s.returncode == 0
-    if not ok or args.cmd or args.shell:
+    skip_shell = False
+    if not ok or args.cmd or args.rebuild or args.shell:
         cmd_chk(['packaging/prep-auto-dir'], discard='output')
     if not ok:
         print(f'"git merge {based_on}" incomplete -- please fix.')
         if not run_a_shell(parent, patch):
             return 0
+        if not args.rebuild and not args.cmd:
+            skip_shell = True
+    if args.rebuild:
+        if cmd_run(['packaging/smart-rebuild']).returncode != 0:
+            if not run_a_shell(parent, patch):
+                return 0
+            if not args.cmd:
+                skip_shell = True
     if args.cmd:
         if cmd_run(args.cmd).returncode != 0:
             if not run_a_shell(parent, patch):
                 return 0
-            ok = False
-    if ok and args.shell:
+            skip_shell = True
+    if args.shell and not skip_shell:
         if not run_a_shell(parent, patch):
             return 0
 
@@ -220,6 +229,7 @@ if __name__ == '__main__':
     parser.add_argument('--skip-check', action='store_true', help="Skip the check that ensures starting with a clean branch.")
     parser.add_argument('--shell', '-s', action='store_true', help="Launch a shell for every patch/BASE/* branch updated, not just when a conflict occurs.")
     parser.add_argument('--cmd', '-c', help="Run a command in every patch branch.")
+    parser.add_argument('--rebuild', '-r', help="Run the smart-rebuild script in every patch branch.")
     parser.add_argument('--gen', metavar='DIR', nargs='?', const='', help='Include generated files. Optional DIR value overrides the default of using the "patches" dir.')
     parser.add_argument('--patches-dir', '-p', metavar='DIR', default='patches', help="Override the location of the rsync-patches dir. Default: patches.")
     parser.add_argument('patch_files', metavar='patches/DIFF_FILE', nargs='*', help="Specify what patch diff files to process. Default: all of them.")

packaging/smart-rebuild

@@ -0,0 +1,39 @@
+#!/bin/sh -e
+
+make=`which make || which gmake`
+
+branch=`packaging/prep-auto-dir`
+if test x"$branch" = x; then
+    srcdir=.
+else
+    cd build
+    srcdir=..
+fi
+
+if test -f configure.sh; then
+    cp -p configure.sh configure.sh.old
+else
+    touch configure.sh.old
+fi
+
+if test -f .fetch; then
+    $srcdir/prepare-source fetch
+else
+    $srcdir/prepare-source
+fi
+
+if diff configure.sh configure.sh.old >/dev/null 2>&1; then
+    echo "configure.sh is unchanged."
+    rm configure.sh.old
+else
+    echo "configure.sh has CHANGED."
+    ./config.status --recheck
+fi
+
+./config.status
+
+$make all
+
+if test x"$1" = x"check"; then
+    $make check
+fi