gdb: handle calls to edit command passing only a linespec condition

While working on the previous commit to fix PR cli/28665, I noticed
that the 'edit' command would suffer from the same problem.  That is,
something like:

  (gdb) edit task 123

would cause GDB to break.  For a full explanation of what's going on
here, see the commit message for the previous commit.

As with the previous commit, this issue can be prevented by detecting,
and throwing, a junk at the end of the line error earlier, before
calling decode_line_1.

So, that's what this commit does.  I've also added some tests for this
issue.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=28665

1 files changed, 16 insertions, 10 deletions

diff --git a/gdb/testsuite/gdb.linespec/errors.exp b/gdb/testsuite/gdb.linespec/errors.exp
index e258f6b..c895e25 100644
--- a/gdb/testsuite/gdb.linespec/errors.exp
+++ b/gdb/testsuite/gdb.linespec/errors.exp
@@ -29,13 +29,19 @@ gdb_test "list fooc:/foo/bar/baz.c:1" "No source file named fooc."
 gdb_test "list fooc:/foo/bar/baz.c" "No source file named fooc."
 
 # PR cli/28665, gdb/28797
-gdb_test "list task 123" \
-    "Junk at end of line specification\\."
-gdb_test "list if (0)" \
-    "Junk at end of line specification\\."
-gdb_test "list thread 1" \
-    "Junk at end of line specification\\."
-gdb_test "list -force-condition" \
-    "Junk at end of line specification\\."
-gdb_test "list ,," \
-    "Junk at end of line specification\\."
+save_vars { env(EDITOR) } {
+    setenv EDITOR true
+
+    foreach cmd {list edit} {
+	gdb_test "${cmd} task 123" \
+	    "Junk at end of line specification\\."
+	gdb_test "${cmd} if (0)" \
+	    "Junk at end of line specification\\."
+	gdb_test "${cmd} thread 1" \
+	    "Junk at end of line specification\\."
+	gdb_test "${cmd} -force-condition" \
+	    "Junk at end of line specification\\."
+	gdb_test "${cmd} ,," \
+	    "Junk at end of line specification\\."
+    }
+}