This patch changes the default value of 'dict-dir' to correspond
to ~/.guix-profile/lib/aspell rather than $prefix/lib/aspell-X.Y.

This is not strictly necessary for the 'aspell' program itself since
one can simply set "ASPELL_CONF=dict-dir $HOME/.guix-profile/lib/aspell".
However it is necessary for applications that use libaspell since
'ASPELL_CONF' is not honored in this case.  See <https://bugs.gnu.org/25836>.

--- a/common/config.cpp
+++ b/common/config.cpp
@@ -651,7 +651,20 @@ namespace acommon {
 	  } else { // sep == '|'
 	    assert(replace[0] == '$');
 	    const char * env = getenv(replace.c_str()+1);
-	    final_str += env ? env : second;
+	    if (env) {
+	      final_str += env;
+	    } else if (second[0] == '$') {
+	      // Expand the right-hand side of '|', which starts with a
+	      // reference to an environment variable.
+	      auto slash = second.find('/');
+	      String variable = second.substr(1, slash - 1);
+	      const char * env = getenv(variable.c_str());
+	      String value = env ? String(env) : "";
+	      value += second.substr(slash, second.size() - slash);
+	      final_str += value;
+	    } else {
+	      final_str += second;
+	    }
 	  }
 	  replace = "";
 	  in_replace = false;
@@ -1349,6 +1349,9 @@ namespace acommon {
 #  define REPL     ".aspell.<lang>.prepl"
 #endif
 
+#undef DICT_DIR
+#define DICT_DIR "<$ASPELL_DICT_DIR|$HOME/.guix-profile/lib/aspell>"
+
   static const KeyInfo config_keys[] = {
     // the description should be under 50 chars
     {"actual-dict-dir", KeyInfoString, "<dict-dir^master>", 0}
og/tests/build-utils.scm'>
<input type='hidden' name='id' value='cc8d346b9613b3b38ba2eaaecb1dcdf9dbaa068b'/><select name='qt'>
<option value='grep'>log msg</option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=cc8d346b9613b3b38ba2eaaecb1dcdf9dbaa068b'>root</a>/<a href='/guix/log/tests?id=cc8d346b9613b3b38ba2eaaecb1dcdf9dbaa068b'>tests</a>/<a href='/guix/log/tests/build-utils.scm?id=cc8d346b9613b3b38ba2eaaecb1dcdf9dbaa068b'>build-utils.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/tests/build-utils.scm?id=cc8d346b9613b3b38ba2eaaecb1dcdf9dbaa068b&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2016-09-07 23:59:02 +0200'>2016-09-07</span></td><td><a href='/guix/commit/tests/build-utils.scm?id=b14a8385095f6672960fb8378c6578acf1ebbf8a'>utils: 'wrap-program' produces only one wrapper file.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2016-09-02 15:39:10 +0200'>2016-09-02</span></td><td><a href='/guix/commit/tests/build-utils.scm?id=7370c021483e428a9da15cdf8693d42fe75ecc62'>tests: Test 'wrap-program' without building a package.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2016-04-03 14:19:09 +0200'>2016-04-03</span></td><td><a href='/guix/commit/tests/build-utils.scm?id=a9edb211e733b8b34e67ec3b4450567e9376986f'>build: Add a Guile custom test driver using SRFI-64.</a><span class='msg-avail'>...</span></td><td>Mathieu Lirzin</td></tr>