testcase for PR symtab/17855

gdb/testsuite/ChangeLog:

	PR symtab/17855
	* gdb.ada/exec_changed.exp: Add second test where symbol lookup cache
	is read after symbols have been re-read.
	* gdb.ada/exec_changed/first.adb (First): New procedure Break_Me.
	* gdb.ada/exec_changed/second.adb (Second): Ditto.

gdb/testsuite/ChangeLog

@@ -1,3 +1,11 @@
+2015-02-22  Doug Evans  <xdje42@gmail.com>
+
+	PR symtab/17855
+	* gdb.ada/exec_changed.exp: Add second test where symbol lookup cache
+	is read after symbols have been re-read.
+	* gdb.ada/exec_changed/first.adb (First): New procedure Break_Me.
+	* gdb.ada/exec_changed/second.adb (Second): Ditto.
+
 2015-02-21  Doug Evans  <dje@google.com>
 
 	* gdb.cp/anon-ns.exp: Add test for ptype '(anonymous namespace)'.

gdb/testsuite/gdb.ada/exec_changed.exp

@@ -81,3 +81,30 @@ if { [gdb_start_cmd] < 0 } {
              "second \\(\\) at .*second.adb.*" \
              "start second"
 }
+
+# Try again, this time with just changing the file time of first.
+
+clean_restart "${binfile}$EXEEXT"
+
+# Ensure we don't accidently use the main symbol cache.
+gdb_test_no_output "mt set symbol-cache-size 0"
+
+# Put something in the symbol lookup cache that will get looked up when
+# starting after having re-read symbols.  PR 17855.
+gdb_breakpoint break_me
+
+gdb_test "shell touch ${binfile}$EXEEXT" ".*" ""
+gdb_test "shell sleep 1" ".*" ""
+
+if { [gdb_start_cmd] < 0 } {
+    # PR 17855: At this point gdb may have crashed or gotten an internal
+    # error, but we still need to detect this.  Just issue any simple command
+    # to verify gdb is still running.  This will establish in gdb.log whether
+    # gdb is still running.
+    gdb_test_no_output "set \$check_gdb_running = 0" "check gdb running"
+    fail "start just first"
+} else {
+    gdb_test "" \
+	"first \\(\\) at .*first.adb.*" \
+	"start just first"
+}

gdb/testsuite/gdb.ada/exec_changed/first.adb

@@ -14,6 +14,12 @@
 --  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 procedure First is
+
+   procedure Break_Me is
+   begin
+      null;
+   end Break_Me;
+
 begin
-   null;
+   Break_Me;
 end First;

gdb/testsuite/gdb.ada/exec_changed/second.adb

@@ -14,6 +14,12 @@
 --  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 procedure Second is
+
+   procedure Break_Me is
+   begin
+      null;
+   end Break_Me;
+
 begin
-   null;
+   Break_Me;
 end Second;