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Re: Tip: use of GDB with Java/gcj (and ant)



Daniel Risacher writes:
 > 
 > I recently started developing with gcj on debian and wanted to use
 > gdb for debugging, but I've struggled a bit with it.  I had actually
 > composed a lengthy set of questions to ask here on the list, but in
 > writing the email, I stumbled across the answer, which I now present.
 > 
 > The problem: I wasn't getting any debugging information (line numbers
 > or local symbols into the code when I compiled with ant.  My javac
 > task in build.xml looked like this:
 > 
 >         <javac debug="true" verbose="yes" debuglevel="source" includeJavaRuntime="no" 
 > 	compiler="gcj" destdir="classes">
 >             <src path="src" />
 >             <include name="**/*.java" />
 >             <compilerarg line=" --main=Main -o Coast" />
 >         </javac>
 > 
 > The solution was to change the javac task to this:
 > 
 >         <javac verbose="yes" includeJavaRuntime="no" 
 > 	compiler="gcj" destdir="classes">
 >             <src path="src" />
 >             <include name="**/*.java" />
 >             <compilerarg line="-g --main=Main -o Coast" />
 >         </javac>
 > 
 > Note that the 'debug' and 'debuglevel' properties were removed, and
 > the '-g' option was added to 'compilerarg'
 > 
 > I hope this helps someone else avoid the hand-wringing and
 > teeth-gnashing I went through.

I've come across a few RPMS with missing debuginfo and wasted a great
deal of time trying to rebuild to get the debuginfo.

The problem seems to be that some ant scripts force debugging to be
off or perhaps inherited from a property that no-one remembered to
set.  This is compounded by the fact that some ant scripts unzip source
archives and then call ant recursively to build them: in such a case
it's very hard to patch build.xml to force debugging=true.

This patch for ecj forces debuginfo always to be generated while
rebuilding an RPM, no matter what ant thinks.  I realize it's
something of a kludge, but it's better than the current situation.

When compiling C/C++/etc, RPM passes "-g" in RPM_OPT_FLAGS.  An
alternative to this patch might be to scan RPM_OPT_FLAGS for "-g" and
only turn on debugging if it's present.  However, I doubt that in
practice it'd make any difference.

Something similar would work for Debian.  I know of no circumstances
in which we ever wish to ship packages that don't have debuginfo.

Andrew.



--- eclipse-3.1.1/plugins/org.eclipse.jdt.core/batch/org/eclipse/jdt/internal/compiler/batch/Main.java.orig	2006-01-19 17:53:49.000000000 +0000
+++ eclipse-3.1.1/plugins/org.eclipse.jdt.core/batch/org/eclipse/jdt/internal/compiler/batch/Main.java	2006-01-19 18:06:32.000000000 +0000
@@ -2405,6 +2405,29 @@
 			this.times = new long[this.repetitions];
 			this.timesCounter = 0;
 		}
+
+		{
+			// If we're building an RPM, force full debugging info to
+			// be generated, no matter what options have been passed
+			// by Ant.  This is something of a kludge, but it is far
+			// better than the alternative, which is having class
+			// files with debug info mysteriously missing.
+
+			String RpmPackageName = System.getenv("RPM_PACKAGE_NAME");
+			String RpmArch = System.getenv("RPM_ARCH");
+			String RpmBuildRoot = System.getenv("RPM_BUILD_ROOT");
+			if (RpmPackageName != null && RpmArch != null && RpmBuildRoot != null) {
+				this.options.put(
+			  	    CompilerOptions.OPTION_LocalVariableAttribute,
+			  	    CompilerOptions.GENERATE);
+				this.options.put(
+				    CompilerOptions.OPTION_LineNumberAttribute,
+				    CompilerOptions.GENERATE);
+				this.options.put(
+				    CompilerOptions.OPTION_SourceFileAttribute,
+				    CompilerOptions.GENERATE);
+			}
+		}
 	}
 
 	private void addNewEntry(final int InsideClasspath, final int InsideSourcepath, ArrayList bootclasspaths, ArrayList classpaths,ArrayList sourcepathClasspaths, String currentClasspathName, ArrayList currentRuleSpecs, int mode, String customEncoding) {



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