bootstrap: clean only gnulib's stray links

[Akim Demaille]

Hi!

In Bison we have another submodule, and symlinks pointing
into.  Occasionally, some users launch ./bootstrap before having
initialized the submodules, in which case the symlink is removed
by bootstrap.  When this happens, it takes quite a few interaction
with the user to understand what went wrong (see for instance

https://lists.gnu.org/archive/html/help-bison/2018-12/msg00034.html

and

https://lists.gnu.org/archive/html/bug-bison/2011-05/msg00012.html

This commit restricts this dandling symlink cleaning to those
going into gnulib.

Cheers, and happy new year!


commit bf316bfa3de7cfe7af948ba2ff84f44c252c4c01
Author: Akim Demaille <address@hidden>
Date:   Mon Dec 31 19:20:46 2018 +0100

    bootstrap: clean only gnulib's stray links
    
    * build-aux/bootstrap: Remove only dangling links pointing into
    gnulib.

diff --git a/ChangeLog b/ChangeLog
index 406e08327..5a1971983 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2019-01-01  Akim Demaille  <address@hidden>
+
+       bootstrap: clean only gnulib's stray links
+       * build-aux/bootstrap: Remove only dangling links pointing into
+       gnulib.
+
 2018-12-27  Paul Eggert  <address@hidden>
 
        mkfifo: bring back HAVE_MKFIFO macro
diff --git a/build-aux/bootstrap b/build-aux/bootstrap
index 5264d9f1e..45061733b 100755
--- a/build-aux/bootstrap
+++ b/build-aux/bootstrap
@@ -1,6 +1,6 @@
 #! /bin/sh
 # Print a version string.
-scriptversion=2018-10-13.05; # UTC
+scriptversion=2019-01-01.06; # UTC
 
 # Bootstrap this package from checked-out sources.
 
@@ -963,7 +963,7 @@ fi
 bootstrap_post_import_hook \
   || die "bootstrap_post_import_hook failed"
 
-# Remove any dangling symlink matching "*.m4" or "*.[ch]" in some
+# Remove any dangling symlink into gnulib/ matching "*.m4" or "*.[ch]" in some
 # gnulib-populated directories.  Such .m4 files would cause aclocal to fail.
 # The following requires GNU find 4.2.3 or newer.  Considering the usual
 # portability constraints of this script, that may seem a very demanding
@@ -973,7 +973,15 @@ bootstrap_post_import_hook \
 # between successive runs of this script.
 find "$m4_base" "$source_base" \
   -depth \( -name '*.m4' -o -name '*.[ch]' \) \
-  -type l -xtype l -delete > /dev/null 2>&1
+  -type l -xtype l 2>/dev/null |
+    while read l
+    do
+      case `readlink "$l"` in
+        "`pwd`/$gnulib_path"/*)
+          echo "$me: rm -f $l"
+          rm -f "$l";;
+      esac
+    done
 
 # Invoke autoreconf with --force --install to ensure upgrades of tools
 # such as ylwrap.