Attachment #185336 for bug #332637




/*******************************************************************************
 * Copyright (c) 2000, 2010 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at

 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     Stephan Herrmann - Contribution for bug 332637 - Dead Code detection removing code that isn't dead
 *******************************************************************************/
package org.eclipse.jdt.internal.compiler.ast;


								addPotentialInitializationsFrom(
									handlingContext.initsOnReturn));
				} else {
					FlowInfo initsOnException = handlingContext.initsOnException(this.caughtExceptionTypes[i]);
					catchInfo =
						flowInfo.nullInfoLessUnconditionalCopy()
							.addPotentialInitializationsFrom(initsOnException)
							.addNullInfoFrom(initsOnException)	// null info only from here, this is the only way to enter the catch block
									this.caughtExceptionTypes[i]))
							.addPotentialInitializationsFrom(tryInfo.unconditionalCopy())
							.addPotentialInitializationsFrom(
									tryInfo.nullInfoLessUnconditionalCopy())
							.addPotentialInitializationsFrom(
									handlingContext.initsOnReturn.nullInfoLessUnconditionalCopy());
				}

				// catch var is always set

Lines 7-12 Link Here

(-)compiler/org/eclipse/jdt/internal/compiler/flow/ConditionalFlowInfo.java (+8 lines)
7	*	7	*
8	* Contributors:	8	* Contributors:
9	* IBM Corporation - initial API and implementation	9	* IBM Corporation - initial API and implementation
		10	* Stephan Herrmann - Contribution for bug 332637 - Dead Code detection removing code that isn't dead
10	*******************************************************************************/	11	*******************************************************************************/
11	package org.eclipse.jdt.internal.compiler.flow;	12	package org.eclipse.jdt.internal.compiler.flow;
12		13
Lines 35-40 Link Here
35	return this;	36	return this;
36	}	37	}
37		38
		39	public FlowInfo addNullInfoFrom(FlowInfo otherInits) {
		40
		41	this.initsWhenTrue.addNullInfoFrom(otherInits);
		42	this.initsWhenFalse.addNullInfoFrom(otherInits);
		43	return this;
		44	}
		45
38	public FlowInfo addPotentialInitializationsFrom(FlowInfo otherInits) {	46	public FlowInfo addPotentialInitializationsFrom(FlowInfo otherInits) {
39		47
40	this.initsWhenTrue.addPotentialInitializationsFrom(otherInits);	48	this.initsWhenTrue.addPotentialInitializationsFrom(otherInits);

Lines 7-12 Link Here

(-)compiler/org/eclipse/jdt/internal/compiler/flow/FlowInfo.java (+8 lines)
7	*	7	*
8	* Contributors:	8	* Contributors:
9	* IBM Corporation - initial API and implementation	9	* IBM Corporation - initial API and implementation
		10	* Stephan Herrmann <stephan@cs.tu-berlin.de> - Contribution for bug 332637 - Dead Code detection removing code that isn't dead
10	*******************************************************************************/	11	*******************************************************************************/
11	package org.eclipse.jdt.internal.compiler.flow;	12	package org.eclipse.jdt.internal.compiler.flow;
12		13
Lines 41-46 Link Here
41	*/	42	*/
42	abstract public FlowInfo addInitializationsFrom(FlowInfo otherInits);	43	abstract public FlowInfo addInitializationsFrom(FlowInfo otherInits);
43		44
		45	/**
		46	* Add all null information from otherInits to this flow info and return this.
		47	* The operation models the effect of an unconditional sequence of this flow info
		48	* and otherInits.
		49	*/
		50	abstract public FlowInfo addNullInfoFrom(FlowInfo otherInits);
		51
44		52
45	/**	53	/**
46	* Compose other inits over this flow info, then return this. The operation	54	* Compose other inits over this flow info, then return this. The operation




 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     Stephan Herrmann <stephan@cs.tu-berlin.de> - Contribution for bug 332637   
 *******************************************************************************/
package org.eclipse.jdt.internal.compiler.flow;


	public int[] nullStatusChangedInAssert; // https://bugs.eclipse.org/bugs/show_bug.cgi?id=303448

public FlowInfo addInitializationsFrom(FlowInfo inits) {
	return addInfoFrom(inits, true);
}
public FlowInfo addNullInfoFrom(FlowInfo inits) {
	return addInfoFrom(inits, false);
}
private FlowInfo addInfoFrom(FlowInfo inits, boolean handleInits) {
	if (this == DEAD_END)
		return this;
	if (inits == DEAD_END)
		return this;
	UnconditionalFlowInfo otherInits = inits.unconditionalInits();

	if (handleInits) {
		// union of definitely assigned variables,
		this.definiteInits |= otherInits.definiteInits;
		// union of potentially set ones
		this.potentialInits |= otherInits.potentialInits;
	}
	
	// combine null information
	boolean thisHadNulls = (this.tagBits & NULL_FLAG_MASK) != 0,
		otherHasNulls = (otherInits.tagBits & NULL_FLAG_MASK) != 0;

			}
		}
		int i;
		if (handleInits) {
			// manage definite assignment info
			for (i = 0; i < mergeLimit; i++) {
				this.extra[0][i] |= otherInits.extra[0][i];
				this.extra[1][i] |= otherInits.extra[1][i];
			}
			for (; i < copyLimit; i++) {
				this.extra[0][i] = otherInits.extra[0][i];
				this.extra[1][i] = otherInits.extra[1][i];
			
			}
		}
		// tweak limits for nulls
		if (!thisHadNulls) {




 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     Stephan Herrmann <stephan@cs.tu-berlin.de> - Contribution for bug 332637
 *******************************************************************************/
package org.eclipse.jdt.core.tests.compiler.regression;


			"    o.toString();\n" +
			"  }\n" +
			"}\n"},
			"----------\n" +
		"1. ERROR in X.java (at line 4)\n" +
			"	o.toString();\n" +
			"	^\n" +
		"The variable o may be null\n" +
			"----------\n");
}

// null analysis -- conditional expression


// null analysis - try/catch
public void test0554_try_catch() {
	this.runNegativeTest(
		new String[] {
			"X.java",
			"public class X {\n" +

			"    throw new LocalException();\n" +
			"  }\n" +
			"}\n"},
		"----------\n" +
		"1. ERROR in X.java (at line 10)\n" +
		"	if (o != null) {\n" +
		"	    ^\n" +
		"Null comparison always yields false: The variable o can only be null at this location\n" +
		"----------\n" +
		"2. WARNING in X.java (at line 10)\n" +
		"	if (o != null) {\n" +
		"    }\n" +
		"	               ^^^^^^^\n" +
		"Dead code\n" +
		"----------\n"
	);
}


		"1. ERROR in X.java (at line 13)\n" +
		"	o.toString();\n" +
		"	^\n" +
		"Null pointer access: The variable o can only be null at this location\n" +
		"Potential null pointer access: The variable o may be null at this location\n" +
		// conservative flow analysis softens the error
		"----------\n",
	    JavacTestOptions.Excuse.EclipseWarningConfiguredAsError);
}

		"1. ERROR in X.java (at line 12)\n" +
		"	o.toString();\n" +
		"	^\n" +
		"Null pointer access: The variable o can only be null at this location\n" +
		"Potential null pointer access: The variable o may be null at this location\n" +
		// conservative flow analysis softens the error
		"----------\n",
	    JavacTestOptions.Excuse.EclipseWarningConfiguredAsError);
}

			"}"},
			"Compiler good Compiler good");
}
// https://bugs.eclipse.org/bugs/show_bug.cgi?id=332637 
// Dead Code detection removing code that isn't dead
public void testBug332637() {
	if (this.complianceLevel < ClassFileConstants.JDK1_5)
		return;
	this.runConformTest(
		new String[] {
			"DeadCodeExample.java",
			"public class DeadCodeExample {\n" + 
			"\n" + 
			"	private class CanceledException extends Exception {\n" + 
			"	}\n" + 
			"\n" + 
			"	private interface ProgressMonitor {\n" + 
			"		boolean isCanceled();\n" + 
			"	}\n" + 
			"\n" + 
			"	private void checkForCancellation(ProgressMonitor monitor)\n" + 
			"			throws CanceledException {\n" + 
			"		if (monitor.isCanceled()) {\n" + 
			"			throw new CanceledException();\n" + 
			"		}\n" + 
			"	}\n" + 
			"\n" + 
			"	private int run() {\n" + 
			"\n" + 
			"		ProgressMonitor monitor = new ProgressMonitor() {\n" + 
			"			private int i = 0;\n" + 
			"\n" + 
			"			public boolean isCanceled() {\n" + 
			"				return (++i == 5);\n" + 
			"			}\n" + 
			"		};\n" + 
			"\n" + 
			"		Integer number = null;\n" + 
			"\n" + 
			"		try {\n" + 
			"			checkForCancellation(monitor);\n" + 
			"\n" + 
			"			number = Integer.valueOf(0);\n" + 
			"\n" + 
			"			for (String s : new String[10]) {\n" + 
			"				checkForCancellation(monitor);\n" + 
			"				number++;\n" + 
			"			}\n" + 
			"			return 0;\n" + 
			"		} catch (CanceledException e) {\n" + 
			"			System.out.println(\"Canceled after \" + number\n" + 
			"				+ \" times through the loop\");\n" + 
			"			if (number != null) {\n" + 
			"				System.out.println(\"number = \" + number);\n" + 
			"			}\n" + 
			"			return -1;\n" + 
			"		}\n" + 
			"	}\n" + 
			"\n" + 
			"	public static void main(String[] args) {\n" + 
			"		System.out.println(new DeadCodeExample().run());\n" + 
			"	}\n" + 
			"}\n"				
		});
}
}

Return to bug 332637

Lines 7-12 Link Here

(-)compiler/org/eclipse/jdt/internal/compiler/flow/UnconditionalFlowInfo.java (-12 / +25 lines)
7	*	7	*
8	* Contributors:	8	* Contributors:
9	* IBM Corporation - initial API and implementation	9	* IBM Corporation - initial API and implementation
		10	* Stephan Herrmann <stephan@cs.tu-berlin.de> - Contribution for bug 332637
10	*******************************************************************************/	11	*******************************************************************************/
11	package org.eclipse.jdt.internal.compiler.flow;	12	package org.eclipse.jdt.internal.compiler.flow;
12		13
Lines 87-102 Link Here
87	public int[] nullStatusChangedInAssert; // https://bugs.eclipse.org/bugs/show_bug.cgi?id=303448	88	public int[] nullStatusChangedInAssert; // https://bugs.eclipse.org/bugs/show_bug.cgi?id=303448
88		89
89	public FlowInfo addInitializationsFrom(FlowInfo inits) {	90	public FlowInfo addInitializationsFrom(FlowInfo inits) {
		91	return addInfoFrom(inits, true);
		92	}
		93	public FlowInfo addNullInfoFrom(FlowInfo inits) {
		94	return addInfoFrom(inits, false);
		95	}
		96	private FlowInfo addInfoFrom(FlowInfo inits, boolean handleInits) {
90	if (this == DEAD_END)	97	if (this == DEAD_END)
91	return this;	98	return this;
92	if (inits == DEAD_END)	99	if (inits == DEAD_END)
93	return this;	100	return this;
94	UnconditionalFlowInfo otherInits = inits.unconditionalInits();	101	UnconditionalFlowInfo otherInits = inits.unconditionalInits();
95		102
96	// union of definitely assigned variables,	103	if (handleInits) {
97	this.definiteInits \|= otherInits.definiteInits;	104	// union of definitely assigned variables,
98	// union of potentially set ones	105	this.definiteInits \|= otherInits.definiteInits;
99	this.potentialInits \|= otherInits.potentialInits;	106	// union of potentially set ones
		107	this.potentialInits \|= otherInits.potentialInits;
		108	}
		109
100	// combine null information	110	// combine null information
101	boolean thisHadNulls = (this.tagBits & NULL_FLAG_MASK) != 0,	111	boolean thisHadNulls = (this.tagBits & NULL_FLAG_MASK) != 0,
102	otherHasNulls = (otherInits.tagBits & NULL_FLAG_MASK) != 0;	112	otherHasNulls = (otherInits.tagBits & NULL_FLAG_MASK) != 0;
Lines 218-231 Link Here
218	}	228	}
219	}	229	}
220	int i;	230	int i;
221	// manage definite assignment info	231	if (handleInits) {
222	for (i = 0; i < mergeLimit; i++) {	232	// manage definite assignment info
223	this.extra[0][i] \|= otherInits.extra[0][i];	233	for (i = 0; i < mergeLimit; i++) {
224	this.extra[1][i] \|= otherInits.extra[1][i];	234	this.extra[0][i] \|= otherInits.extra[0][i];
225	}	235	this.extra[1][i] \|= otherInits.extra[1][i];
226	for (; i < copyLimit; i++) {	236	}
227	this.extra[0][i] = otherInits.extra[0][i];	237	for (; i < copyLimit; i++) {
228	this.extra[1][i] = otherInits.extra[1][i];	238	this.extra[0][i] = otherInits.extra[0][i];
		239	this.extra[1][i] = otherInits.extra[1][i];
		240
		241	}
229	}	242	}
230	// tweak limits for nulls	243	// tweak limits for nulls
231	if (!thisHadNulls) {	244	if (!thisHadNulls) {

Lines 7-12 Link Here

(-)src/org/eclipse/jdt/core/tests/compiler/regression/NullReferenceTest.java (-19 / +82 lines)
7	*	7	*
8	* Contributors:	8	* Contributors:
9	* IBM Corporation - initial API and implementation	9	* IBM Corporation - initial API and implementation
		10	* Stephan Herrmann <stephan@cs.tu-berlin.de> - Contribution for bug 332637
10	*******************************************************************************/	11	*******************************************************************************/
11	package org.eclipse.jdt.core.tests.compiler.regression;	12	package org.eclipse.jdt.core.tests.compiler.regression;
12		13
Lines 749-760 Link Here
749	" o.toString();\n" +	750	" o.toString();\n" +
750	" }\n" +	751	" }\n" +
751	"}\n"},	752	"}\n"},
752	"----------\n" +	753	"----------\n" +
753	"1. ERROR in X.java (at line 4)\n" +	754	"1. ERROR in X.java (at line 4)\n" +
754	" o.toString();\n" +	755	" o.toString();\n" +
755	" ^\n" +	756	" ^\n" +
756	"The variable o may be null\n" +	757	"The variable o may be null\n" +
757	"----------\n");	758	"----------\n");
758	}	759	}
759		760
760	// null analysis -- conditional expression	761	// null analysis -- conditional expression
Lines 5598-5604 Link Here
5598		5599
5599	// null analysis - try/catch	5600	// null analysis - try/catch
5600	public void test0554_try_catch() {	5601	public void test0554_try_catch() {
5601	this.runConformTest(	5602	this.runNegativeTest(
5602	new String[] {	5603	new String[] {
5603	"X.java",	5604	"X.java",
5604	"public class X {\n" +	5605	"public class X {\n" +
Lines 5622-5635 Link Here
5622	" throw new LocalException();\n" +	5623	" throw new LocalException();\n" +
5623	" }\n" +	5624	" }\n" +
5624	"}\n"},	5625	"}\n"},
5625	""	5626	"----------\n" +
5626	// conservative flow analysis suppresses the warning	5627	"1. ERROR in X.java (at line 10)\n" +
5627	// "----------\n" +	5628	" if (o != null) {\n" +
5628	// "1. ERROR in X.java (at line 10)\n" +	5629	" ^\n" +
5629	// " if (o != null) {\n" +	5630	"Null comparison always yields false: The variable o can only be null at this location\n" +
5630	// " ^\n" +	5631	"----------\n" +
5631	// "Redundant null check: The variable o can only be null at this location\n" +	5632	"2. WARNING in X.java (at line 10)\n" +
5632	// "----------\n"	5633	" if (o != null) {\n" +
		5634	" }\n" +
		5635	" ^^^^^^^\n" +
		5636	"Dead code\n" +
		5637	"----------\n"
5633	);	5638	);
5634	}	5639	}
5635		5640
Lines 5748-5756 Link Here
5748	"1. ERROR in X.java (at line 13)\n" +	5753	"1. ERROR in X.java (at line 13)\n" +
5749	" o.toString();\n" +	5754	" o.toString();\n" +
5750	" ^\n" +	5755	" ^\n" +
5751	// "Null pointer access: The variable o can only be null at this location\n" +	5756	"Null pointer access: The variable o can only be null at this location\n" +
5752	"Potential null pointer access: The variable o may be null at this location\n" +
5753	// conservative flow analysis softens the error
5754	"----------\n",	5757	"----------\n",
5755	JavacTestOptions.Excuse.EclipseWarningConfiguredAsError);	5758	JavacTestOptions.Excuse.EclipseWarningConfiguredAsError);
5756	}	5759	}
Lines 5785-5793 Link Here
5785	"1. ERROR in X.java (at line 12)\n" +	5788	"1. ERROR in X.java (at line 12)\n" +
5786	" o.toString();\n" +	5789	" o.toString();\n" +
5787	" ^\n" +	5790	" ^\n" +
5788	// "Null pointer access: The variable o can only be null at this location\n" +	5791	"Null pointer access: The variable o can only be null at this location\n" +
5789	"Potential null pointer access: The variable o may be null at this location\n" +
5790	// conservative flow analysis softens the error
5791	"----------\n",	5792	"----------\n",
5792	JavacTestOptions.Excuse.EclipseWarningConfiguredAsError);	5793	JavacTestOptions.Excuse.EclipseWarningConfiguredAsError);
5793	}	5794	}
Lines 12664-12667 Link Here
12664	"}"},	12665	"}"},
12665	"Compiler good Compiler good");	12666	"Compiler good Compiler good");
12666	}	12667	}
		12668	// https://bugs.eclipse.org/bugs/show_bug.cgi?id=332637
		12669	// Dead Code detection removing code that isn't dead
		12670	public void testBug332637() {
		12671	if (this.complianceLevel < ClassFileConstants.JDK1_5)
		12672	return;
		12673	this.runConformTest(
		12674	new String[] {
		12675	"DeadCodeExample.java",
		12676	"public class DeadCodeExample {\n" +
		12677	"\n" +
		12678	" private class CanceledException extends Exception {\n" +
		12679	" }\n" +
		12680	"\n" +
		12681	" private interface ProgressMonitor {\n" +
		12682	" boolean isCanceled();\n" +
		12683	" }\n" +
		12684	"\n" +
		12685	" private void checkForCancellation(ProgressMonitor monitor)\n" +
		12686	" throws CanceledException {\n" +
		12687	" if (monitor.isCanceled()) {\n" +
		12688	" throw new CanceledException();\n" +
		12689	" }\n" +
		12690	" }\n" +
		12691	"\n" +
		12692	" private int run() {\n" +
		12693	"\n" +
		12694	" ProgressMonitor monitor = new ProgressMonitor() {\n" +
		12695	" private int i = 0;\n" +
		12696	"\n" +
		12697	" public boolean isCanceled() {\n" +
		12698	" return (++i == 5);\n" +
		12699	" }\n" +
		12700	" };\n" +
		12701	"\n" +
		12702	" Integer number = null;\n" +
		12703	"\n" +
		12704	" try {\n" +
		12705	" checkForCancellation(monitor);\n" +
		12706	"\n" +
		12707	" number = Integer.valueOf(0);\n" +
		12708	"\n" +
		12709	" for (String s : new String[10]) {\n" +
		12710	" checkForCancellation(monitor);\n" +
		12711	" number++;\n" +
		12712	" }\n" +
		12713	" return 0;\n" +
		12714	" } catch (CanceledException e) {\n" +
		12715	" System.out.println(\"Canceled after \" + number\n" +
		12716	" + \" times through the loop\");\n" +
		12717	" if (number != null) {\n" +
		12718	" System.out.println(\"number = \" + number);\n" +
		12719	" }\n" +
		12720	" return -1;\n" +
		12721	" }\n" +
		12722	" }\n" +
		12723	"\n" +
		12724	" public static void main(String[] args) {\n" +
		12725	" System.out.println(new DeadCodeExample().run());\n" +
		12726	" }\n" +
		12727	"}\n"
		12728	});
		12729	}
12667	}	12730	}

Lines 1-5 Link Here

(-)compiler/org/eclipse/jdt/internal/compiler/ast/TryStatement.java (-8 / +9 lines)
1	/*******************************************************************************	1	/*******************************************************************************
2	* Copyright (c) 2000, 2009 IBM Corporation and others.	2	* Copyright (c) 2000, 2010 IBM Corporation and others.
3	* All rights reserved. This program and the accompanying materials	3	* All rights reserved. This program and the accompanying materials
4	* are made available under the terms of the Eclipse Public License v1.0	4	* are made available under the terms of the Eclipse Public License v1.0
5	* which accompanies this distribution, and is available at	5	* which accompanies this distribution, and is available at
Lines 7-12 Link Here
7	*	7	*
8	* Contributors:	8	* Contributors:
9	* IBM Corporation - initial API and implementation	9	* IBM Corporation - initial API and implementation
		10	* Stephan Herrmann - Contribution for bug 332637 - Dead Code detection removing code that isn't dead
10	*******************************************************************************/	11	*******************************************************************************/
11	package org.eclipse.jdt.internal.compiler.ast;	12	package org.eclipse.jdt.internal.compiler.ast;
12		13
Lines 126-140 Link Here
126	addPotentialInitializationsFrom(	127	addPotentialInitializationsFrom(
127	handlingContext.initsOnReturn));	128	handlingContext.initsOnReturn));
128	} else {	129	} else {
		130	FlowInfo initsOnException = handlingContext.initsOnException(this.caughtExceptionTypes[i]);
129	catchInfo =	131	catchInfo =
130	flowInfo.unconditionalCopy().	132	flowInfo.nullInfoLessUnconditionalCopy()
131	addPotentialInitializationsFrom(	133	.addPotentialInitializationsFrom(initsOnException)
132	handlingContext.initsOnException(	134	.addNullInfoFrom(initsOnException) // null info only from here, this is the only way to enter the catch block
133	this.caughtExceptionTypes[i]))
134	.addPotentialInitializationsFrom(tryInfo.unconditionalCopy())
135	.addPotentialInitializationsFrom(	135	.addPotentialInitializationsFrom(
136	handlingContext.initsOnReturn.	136	tryInfo.nullInfoLessUnconditionalCopy())
137	nullInfoLessUnconditionalCopy());	137	.addPotentialInitializationsFrom(
		138	handlingContext.initsOnReturn.nullInfoLessUnconditionalCopy());
138	}	139	}
139		140
140	// catch var is always set	141	// catch var is always set