Fix NPE in KotlinWhenStringFilter (bazel-contrib#942)

Author: Godin

org.jacoco.core.test/src/org/jacoco/core/internal/analysis/filter/KotlinWhenStringFilterTest.java

@@ -105,4 +105,21 @@ public void should_filter() {
 		assertIgnored(new Range(expectedFromInclusive, expectedToInclusive));
 	}
 
+	@Test
+	public void should_not_filter_empty_lookup_switch() {
+		final MethodNode m = new MethodNode(InstrSupport.ASM_API_VERSION, 0,
+				"name", "(Ljava/lang/String;)V", null, null);
+		m.visitVarInsn(Opcodes.ALOAD, 1);
+		m.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/lang/String", "hashCode",
+				"()I", false);
+		final Label defaultCase = new Label();
+		m.visitLookupSwitchInsn(defaultCase, null, new Label[] {});
+		m.visitLabel(defaultCase);
+		m.visitInsn(Opcodes.RETURN);
+
+		filter.filter(m, context, output);
+
+		assertIgnored();
+	}
+
 }

org.jacoco.core/src/org/jacoco/core/internal/analysis/filter/KotlinWhenStringFilter.java

@@ -67,6 +67,10 @@ public void match(final AbstractInsnNode start,
 				hashCodes = tableSwitch.labels.size();
 			}
 
+			if (hashCodes == 0) {
+				return;
+			}
+
 			final Set<AbstractInsnNode> replacements = new HashSet<AbstractInsnNode>();
 			replacements.add(skipNonOpcodes(defaultLabel));
 

org.jacoco.doc/docroot/doc/changes.html

@@ -47,6 +47,8 @@ <h3>Fixed bugs</h3>
   <li>To avoid failures with invalid class files report generation now checks
       that source references are actually files
       (GitHub <a href="https://github.com/jacoco/jacoco/issues/941">#941</a>).</li>
+  <li><code>NullPointerException</code> during filtering
+      (GitHub <a href="https://github.com/jacoco/jacoco/issues/942">#942</a>).</li>
 </ul>
 
 <h3>Non-functional Changes</h3>