Compilation error not raised with ECJ when warnings are raised

* Fixes #4750

Author: srikanth-sankaran

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/ast/AbstractMethodDeclaration.java

@@ -321,12 +321,15 @@ public void generateCode(ClassScope classScope, ClassFile classFile) {
 		}
 		int problemResetPC = 0;
 		CompilationResult unitResult = null;
+		CategorizedProblem problems[] = new CategorizedProblem[0];
 		int problemCount = 0;
 		if (classScope != null) {
 			TypeDeclaration referenceContext = classScope.referenceContext;
 			if (referenceContext != null) {
 				unitResult = referenceContext.compilationResult();
 				problemCount = unitResult.problemCount;
+				if (problemCount > 0)
+					System.arraycopy(unitResult.problems, 0, (problems = new CategorizedProblem[problemCount]), 0, problemCount);
 			}
 		}
 		boolean restart = false;
@@ -347,6 +350,7 @@ public void generateCode(ClassScope classScope, ClassFile classFile) {
 					// reset the problem count to prevent reporting the same warning twice
 					if (unitResult != null) {
 						unitResult.problemCount = problemCount;
+						unitResult.problems = problems;
 					}
 					restart = true;
 				} else if (e.compilationResult == CodeStream.RESTART_CODE_GEN_FOR_UNUSED_LOCALS_MODE) {
@@ -356,6 +360,7 @@ public void generateCode(ClassScope classScope, ClassFile classFile) {
 					// reset the problem count to prevent reporting the same warning twice
 					if (unitResult != null) {
 						unitResult.problemCount = problemCount;
+						unitResult.problems = problems;
 					}
 					restart = true;
 				} else {
@@ -367,8 +372,7 @@ public void generateCode(ClassScope classScope, ClassFile classFile) {
 		// produce a problem method accounting for this fatal error
 		if (abort) {
 			int problemsLength;
-			CategorizedProblem[] problems =
-				this.scope.referenceCompilationUnit().compilationResult.getAllProblems();
+			problems = this.scope.referenceCompilationUnit().compilationResult.getAllProblems();
 			CategorizedProblem[] problemsCopy = new CategorizedProblem[problemsLength = problems.length];
 			System.arraycopy(problems, 0, problemsCopy, 0, problemsLength);
 			classFile.addProblemMethod(this, this.binding, problemsCopy, problemResetPC);

org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/BatchCompilerTest.java

@@ -13358,4 +13358,86 @@ public void testBug550255() {
 		+ "1 problem (1 warning)\n",
 		true);
 }
+// https://github.com/eclipse-jdt/eclipse.jdt.core/issues/4750
+// Compilation error not raised with ECJ when warnings are raised
+public void testIssue4750() {
+	this.runNegativeTest(
+		new String[] {
+			"X.java",
+			"""
+			public class X {
+				public void testIssue() throws Exception {
+					int N_ITERATIONS = 10;
+					while (N_ITERATIONS-- > 0) {
+						Object index = 0;
+						Runnable thread = new Runnable() {
+							@Override
+							public void run() {
+								System.out.println(index + 1);
+							}
+						};
+					}
+				}
+			}
+			""",
+		},
+		"\"" + OUTPUT_DIR +  File.separator + "X.java\""
+		+ " -sourcepath \"" + OUTPUT_DIR + "\""
+		+ " -d \"" + OUTPUT_DIR + "\"",
+		"",
+		"----------\n" +
+		"1. WARNING in ---OUTPUT_DIR_PLACEHOLDER---/X.java (at line 5)\n" +
+		"	Object index = 0;\n" +
+		"	       ^^^^^\n" +
+		"The value of the local variable index is not used\n" +
+		"----------\n" +
+		"2. WARNING in ---OUTPUT_DIR_PLACEHOLDER---/X.java (at line 6)\n" +
+		"	Runnable thread = new Runnable() {\n" +
+		"	         ^^^^^^\n" +
+		"The value of the local variable thread is not used\n" +
+		"----------\n" +
+		"3. ERROR in ---OUTPUT_DIR_PLACEHOLDER---/X.java (at line 9)\n" +
+		"	System.out.println(index + 1);\n" +
+		"	                   ^^^^^^^^^\n" +
+		"The operator + is undefined for the argument type(s) Object, int\n" +
+		"----------\n" +
+		"3 problems (1 error, 2 warnings)\n",
+		true);
+}
+// https://github.com/eclipse-jdt/eclipse.jdt.core/issues/4750
+// Compilation error not raised with ECJ when warnings are raised
+public void testIssue4750_nowarn() {
+	this.runNegativeTest(
+		new String[] {
+			"X.java",
+			"""
+			public class X {
+				public void testIssue() throws Exception {
+					int N_ITERATIONS = 10;
+					while (N_ITERATIONS-- > 0) {
+						Object index = 0;
+						Runnable thread = new Runnable() {
+							@Override
+							public void run() {
+								System.out.println(index + 1);
+							}
+						};
+					}
+				}
+			}
+			""",
+		},
+		"\"" + OUTPUT_DIR +  File.separator + "X.java\""
+		+ " -sourcepath \"" + OUTPUT_DIR + "\""
+		+ " -nowarn -d \"" + OUTPUT_DIR + "\"",
+		"",
+		"----------\n" +
+		"1. ERROR in ---OUTPUT_DIR_PLACEHOLDER---/X.java (at line 9)\n" +
+		"	System.out.println(index + 1);\n" +
+		"	                   ^^^^^^^^^\n" +
+		"The operator + is undefined for the argument type(s) Object, int\n" +
+		"----------\n" +
+		"1 problem (1 error)\n",
+		true);
+}
 }