Make "cannot 'destroy this' in constructor" error a warning for now (#1105)

To prevent breaking changes without prior announcement

Author: Frotty

de.peeeq.wurstscript/src/main/java/de/peeeq/wurstscript/validation/WurstValidator.java

@@ -1850,8 +1850,7 @@ private void visit(ModuleDef moduleDef) {
     private void visit(ExprDestroy stmtDestroy) {
         if (stmtDestroy.getDestroyedObj() instanceof ExprThis) {
             if (isInConstructor(stmtDestroy)) {
-                stmtDestroy.addError("Cannot destroy 'this' in constructor");
-                return;
+                stmtDestroy.addWarning("Should not destroy 'this' in constructor, because 'new' would return an invalid object.\nMove destruction logic into a separate function outside the constructor.\nThis will be an error in the future.");
             }
         }
 

de.peeeq.wurstscript/src/test/java/tests/wurstscript/tests/BugTests.java

@@ -1462,7 +1462,7 @@ public void duplicateNameInClassHierachy() {
 
     @Test
     public void callingDestroyThisInConstructor() {
-        testAssertErrorsLines(false, "Cannot destroy 'this' in constructor",
+        testAssertWarningsLines(false, "Should not destroy 'this' in constructor",
             "package test",
             "native testSuccess()",
             "class A",

de.peeeq.wurstscript/src/test/java/tests/wurstscript/tests/WurstScriptTest.java

@@ -63,6 +63,8 @@ class TestConfig {
         private boolean executeTests;
         private boolean executeProgOnlyAfterTransforms;
         private String expectedError;
+        private String expectedWarning;
+
         private final List<File> inputFiles = new ArrayList<>();
         private final List<CU> additionalCompilationUnits = new ArrayList<>();
         private boolean stopOnFirstError = true;
@@ -106,6 +108,11 @@ TestConfig executeProg(boolean b) {
             return this;
         }
 
+        TestConfig expectWarning(String expectedWarning) {
+            this.expectedWarning = expectedWarning;
+            return this;
+        }
+
         public TestConfig executeProgOnlyAfterTransforms() {
             this.executeProgOnlyAfterTransforms = true;
             return this;
@@ -149,6 +156,18 @@ CompilationResult run() {
                         }
                     }
                 }
+                if (expectedWarning != null) {
+                    List<CompileError> warnings = res.getGui().getWarningList();
+                    if (warnings.isEmpty()) {
+                        fail("No warnings were discovered");
+                    } else if (warnings.stream()
+                        .noneMatch(w -> w.getMessage().toLowerCase().contains(expectedWarning.toLowerCase()))) {
+                        for (CompileError w : warnings) {
+                            System.err.println("Unexpected warning:" + w);
+                        }
+                        throw new RuntimeException("Unexpected warning", warnings.get(0));
+                    }
+                }
                 return res;
             } catch (CompileError e) {
                 if (expectedError != null) {
@@ -355,6 +374,23 @@ void testAssertErrors(String name, boolean executeProg, String prog, String erro
         test().executeProg(executeProg).expectError(errorMessage).lines(prog);
     }
 
+    public void testAssertWarningsLines(boolean executeProg, String warningMessage, String... input) {
+        test()
+            .setStopOnFirstError(false)
+            .executeProg(executeProg)
+            .expectWarning(warningMessage)
+            .lines(input);
+    }
+
+    public void testAssertWarningsLinesWithStdLib(boolean executeProg, String warningMessage, String... input) {
+        test()
+            .withStdLib()
+            .setStopOnFirstError(false)
+            .executeProg(executeProg)
+            .expectWarning(warningMessage)
+            .lines(input);
+    }
+
     protected WurstModel testScript(String name, boolean executeProg, String prog) {
         return test().executeProg(executeProg).lines(prog).getModel();
     }