GEP-16/GEP-20 overlap cleanup now that both are merged.

Author: paulk-asert

src/antlr/GroovyParser.g4

@@ -584,11 +584,11 @@ typeNamePairs
     ;
 
 typeNamePair
-    :   (DEF | VAR | type)? MUL? variableDeclaratorId
+    :   (DEF | VAL | VAR | type)? MUL? variableDeclaratorId
     ;
 
 keyedPair
-    :   key=identifier COLON (DEF | VAR | type)? variableDeclaratorId
+    :   key=identifier COLON (DEF | VAL | VAR | type)? variableDeclaratorId
     ;
 
 variableNames

src/main/java/org/apache/groovy/parser/antlr4/AstBuilder.java

@@ -2228,13 +2228,17 @@ public VariableExpression visitTypeNamePair(final TypeNamePairContext ctx) {
         boolean isRest = asBoolean(ctx.MUL());
         // GEP-20: typed rest (e.g. `def (h, List<Integer> *t) = list`) is accepted; the
         // declared container type is honoured by static type checking and runtime coercion.
-        // `def` and `var` are also accepted in place of a type (equivalent to omitting it),
-        // for symmetry with switch case patterns and the bracket-form declaration grammar.
+        // `def`, `val`, and `var` are also accepted in place of a type (equivalent to omitting
+        // it), for symmetry with switch case patterns and the bracket-form declaration grammar.
+        // `val` additionally marks the binding as final.
         VariableExpression ve = configureAST(
                 new VariableExpression(
                         this.visitVariableDeclaratorId(ctx.variableDeclaratorId()).getName(),
-                        binderType(ctx.DEF(), ctx.VAR(), ctx.type())),
+                        binderType(ctx.DEF(), ctx.VAL(), ctx.VAR(), ctx.type())),
                 ctx);
+        if (asBoolean(ctx.VAL())) {
+            ve.setModifiers(ve.getModifiers() | Opcodes.ACC_FINAL);
+        }
         if (isRest) {
             ve.putNodeMetaData(MultipleAssignmentMetadata.REST_BINDING, Boolean.TRUE);
         }
@@ -2246,15 +2250,18 @@ public VariableExpression visitKeyedPair(final KeyedPairContext ctx) {
         VariableExpression ve = configureAST(
                 new VariableExpression(
                         this.visitVariableDeclaratorId(ctx.variableDeclaratorId()).getName(),
-                        binderType(ctx.DEF(), ctx.VAR(), ctx.type())),
+                        binderType(ctx.DEF(), ctx.VAL(), ctx.VAR(), ctx.type())),
                 ctx);
+        if (asBoolean(ctx.VAL())) {
+            ve.setModifiers(ve.getModifiers() | Opcodes.ACC_FINAL);
+        }
         ve.putNodeMetaData(MultipleAssignmentMetadata.MAP_KEY, this.visitIdentifier(ctx.key));
         return ve;
     }
 
-    /** GEP-20: resolve a binder's declared type — `def`/`var` produce the dynamic type, same as omitting a type. */
-    private ClassNode binderType(final TerminalNode defNode, final TerminalNode varNode, final TypeContext typeCtx) {
-        if (asBoolean(defNode) || asBoolean(varNode)) return ClassHelper.dynamicType();
+    /** GEP-20: resolve a binder's declared type — `def`/`val`/`var` produce the dynamic type, same as omitting a type. */
+    private ClassNode binderType(final TerminalNode defNode, final TerminalNode valNode, final TerminalNode varNode, final TypeContext typeCtx) {
+        if (asBoolean(defNode) || asBoolean(valNode) || asBoolean(varNode)) return ClassHelper.dynamicType();
         return this.visitType(typeCtx);
     }
 

src/test/groovy/gls/statements/MultipleAssignmentDeclarationTest.groovy

@@ -1572,8 +1572,9 @@ final class MultipleAssignmentDeclarationTest {
         '''
     }
 
-    // GEP-20 def/var binders: accepted in place of a type, equivalent to omitting it.
+    // GEP-20 def/val/var binders: accepted in place of a type, equivalent to omitting it.
     // Provided for symmetry with switch case patterns and the GEP-19 bracket-form grammar.
+    // `val` additionally marks the binding as final.
 
     @Test
     void testDefBinder_positional() {
@@ -1591,6 +1592,14 @@ final class MultipleAssignmentDeclarationTest {
         '''
     }
 
+    @Test
+    void testValBinder_positional() {
+        assertScript '''
+            def (val a, val b) = [1, 2]
+            assert a == 1 && b == 2
+        '''
+    }
+
     @Test
     void testMixedDefVarTypedBinder() {
         assertScript '''
@@ -1599,6 +1608,14 @@ final class MultipleAssignmentDeclarationTest {
         '''
     }
 
+    @Test
+    void testMixedDefValVarTypedBinder() {
+        assertScript '''
+            def (def a, val b, var c, int d) = [1, 2, 3, 4]
+            assert a == 1 && b == 2 && c == 3 && d == 4
+        '''
+    }
+
     @Test
     void testVarBinder_withRest() {
         assertScript '''
@@ -1608,6 +1625,15 @@ final class MultipleAssignmentDeclarationTest {
         '''
     }
 
+    @Test
+    void testValBinder_withRest() {
+        assertScript '''
+            def (val h, *t) = [1, 2, 3]
+            assert h == 1
+            assert t == [2, 3]
+        '''
+    }
+
     @Test
     void testVarBinder_mapStyle() {
         assertScript '''
@@ -1616,6 +1642,14 @@ final class MultipleAssignmentDeclarationTest {
         '''
     }
 
+    @Test
+    void testValBinder_mapStyle() {
+        assertScript '''
+            def (name: val n, age: val a) = [name: 'X', age: 9]
+            assert n == 'X' && a == 9
+        '''
+    }
+
     @Test
     void testVarBinder_CompileStatic_listLiteral() {
         assertScript '''import groovy.transform.CompileStatic
@@ -1628,6 +1662,18 @@ final class MultipleAssignmentDeclarationTest {
         '''
     }
 
+    @Test
+    void testValBinder_CompileStatic_listLiteral() {
+        assertScript '''import groovy.transform.CompileStatic
+            @CompileStatic
+            def go() {
+                def (val a, val b) = [10, 20]
+                assert a == 10 && b == 20
+            }
+            go()
+        '''
+    }
+
     @Test
     void testVarBinder_CompileStatic_mapStyle() {
         assertScript '''import groovy.transform.CompileStatic
@@ -1640,6 +1686,38 @@ final class MultipleAssignmentDeclarationTest {
         '''
     }
 
+    @Test
+    void testValBinder_CompileStatic_mapStyle() {
+        assertScript '''import groovy.transform.CompileStatic
+            @CompileStatic
+            def go() {
+                def (name: val n) = [name: 'Z']
+                assert n == 'Z'
+            }
+            go()
+        '''
+    }
+
+    @Test // GROOVY-11977: val inner binder makes only that name final
+    void testValBinder_finality_perBinder() {
+        def e = shouldFail '''
+            def (val a, var b) = [1, 2]
+            b = 99      // OK
+            a = 99      // rejected
+        '''
+        assert e.message.contains('final')
+    }
+
+    @Test // GROOVY-11977: val inner binder under map-style enforces finality
+    void testValBinder_mapStyle_finality() {
+        def e = shouldFail '''
+            def (name: val n, age: var a) = [name: 'X', age: 9]
+            a = 10      // OK
+            n = 'Y'     // rejected
+        '''
+        assert e.message.contains('final')
+    }
+
     // GEP-20 edge cases: empty Map literal, null RHS, Map missing-key with primitive
     // vs Object binders, classic for-init multi-assignment, method-returning-typed.