Fixup for "[dsf-gdb] debug tests: Use line tags where possible"

Unfortunately previous commit was submitted too early. There were
two problems that this commit corrects:

1) clear line tags before each test run - side effect of Bug 508642

When a test marked with Intermittent fails, the next retry is executed
with the same class instance.  Therefore, the new try starts with a
non-empty fTagLocations.  The test trips on the check that there are no
duplicate tags.

2) Fix failing testStopAtMainWithReverse

A blank line got inserted into the test case, that
interfered with the test logic.

Change-Id: If4c28557eac7ee740b4e3a5eac5dd2726c39a35d
Also-by: Jonah Graham <jonah@kichwacoders.com>
Signed-off-by: Simon Marchi <simon.marchi@polymtl.ca>

dsf-gdb/org.eclipse.cdt.tests.dsf.gdb/data/launch/src/LaunchConfigurationAndRestartTestApp.cc

@@ -25,9 +25,8 @@ int envTest() {
 int main (int argc, char *argv[])
 {
     envTest(); // FIRST_LINE_IN_MAIN
-    reverseTest();
-    stopAtOther();
-
+    reverseTest(); // tests assume that every line between first and last
+    stopAtOther(); // is steppable, so no blank lines allowed.
     return 36; // LAST_LINE_IN_MAIN
     // Return special value to allow
     // testing exit code feature

dsf-gdb/org.eclipse.cdt.tests.dsf.gdb/src/org/eclipse/cdt/tests/dsf/gdb/framework/BaseTestCase.java

@@ -337,6 +337,20 @@ public class BaseTestCase {
 	   	setGdbVersion();
 	}
 
+    /**
+     * Clear our knowledge of line tags. Must be called before
+     * resolveLineTagLocations in {@link Intermittent} tests.
+     * <p>
+     * This is a workaround for Bug 508642. This may not seem necessary, since
+     * the fTagLocations field is not static and a new instance of the test
+     * class is created for each test. However, when a test marked as
+     * {@link Intermittent} fails, the class instance is re-used, so the content
+     * of the failed try leaks in the new try.
+     */
+    public void clearLineTags() {
+        fTagLocations.clear();
+    }
+
 	/**
 	 * Given a set of tags (strings) to find in sourceFile, populate the
 	 * fTagLocations map with the line numbers where they are found.

dsf-gdb/org.eclipse.cdt.tests.dsf.gdb/src/org/eclipse/cdt/tests/dsf/gdb/tests/LaunchConfigurationAndRestartTest.java

@@ -104,6 +104,7 @@ public class LaunchConfigurationAndRestartTest extends BaseParametrizedTestCase
 		// parameters.  The individual tests will be responsible for starting the launch.
 
 		// Looks up line tags in source file(s).
+		clearLineTags();
 		resolveLineTagLocations(SOURCE_NAME, LINE_TAGS);
 
 		FIRST_LINE_IN_MAIN = getLineForTag("FIRST_LINE_IN_MAIN");