commit ae2ab76faca93cad3059808b14d02f5565275e31
Author: Paul Smith <psmith@gnu.org>
Date:   Tue Nov 30 14:48:52 2010 +0000

    Check if the target-specific variable is the same as the global
    variable, and if so don't try to update it.  Savannah bug #31743.

diff --git a/read.c b/read.c
index 7b5b0dd..761e976 100644
--- a/read.c
+++ b/read.c
@@ -1802,7 +1802,8 @@ record_target_var (struct nameseq *filenames, char *defn,
           int len = strlen(v->name);
 
           gv = lookup_variable (v->name, len);
-          if (gv && (gv->origin == o_env_override || gv->origin == o_command))
+          if (gv && v != gv
+              && (gv->origin == o_env_override || gv->origin == o_command))
             {
               if (v->value != 0)
                 free (v->value);
diff --git a/tests/scripts/features/targetvars b/tests/scripts/features/targetvars
index 6afd48a..a9b8dbe 100644
--- a/tests/scripts/features/targetvars
+++ b/tests/scripts/features/targetvars
@@ -237,6 +237,16 @@ a: ; @echo "$(FOO)"
 
 run_make_test(undef, 'FOO=C', "C f1\n");
 
+# TEST #19: Conditional variables with command-line settings
+
+run_make_test('
+a: FOO ?= f1
+a: ; @echo "$(FOO)"
+',
+              '', "f1\n");
+
+run_make_test(undef, 'FOO=C', "C\n");
+
 # TEST #20: Check for continuation after semicolons
 
 run_make_test(q!