feat(911): add erasableSyntaxOnly

Author: a-tarasyuk

internal/checker/checker.go

@@ -2470,6 +2470,9 @@ func (c *Checker) checkParameter(node *ast.Node) {
 		paramName = node.Name().Text()
 	}
 	if ast.HasSyntacticModifier(node, ast.ModifierFlagsParameterPropertyModifier) {
+		if c.compilerOptions.ErasableSyntaxOnly.IsTrue() {
+			c.error(node, diagnostics.This_syntax_is_not_allowed_when_erasableSyntaxOnly_is_enabled)
+		}
 		if !(ast.IsConstructorDeclaration(fn) && ast.NodeIsPresent(fn.Body())) {
 			c.error(node, diagnostics.A_parameter_property_is_only_allowed_in_a_constructor_implementation)
 		}
@@ -4785,6 +4788,11 @@ func (c *Checker) checkEnumDeclaration(node *ast.Node) {
 	c.checkCollisionsForDeclarationName(node, node.Name())
 	c.checkExportsOnMergedDeclarations(node)
 	c.checkSourceElements(node.Members())
+
+	if c.compilerOptions.ErasableSyntaxOnly.IsTrue() && node.Flags&ast.NodeFlagsAmbient == 0 {
+		c.error(node, diagnostics.This_syntax_is_not_allowed_when_erasableSyntaxOnly_is_enabled)
+	}
+
 	c.computeEnumMemberValues(node)
 	// Spec 2014 - Section 9.3:
 	// It isn't possible for one enum declaration to continue the automatic numbering sequence of another,
@@ -4871,6 +4879,9 @@ func (c *Checker) checkModuleDeclaration(node *ast.Node) {
 	symbol := c.getSymbolOfDeclaration(node)
 	// The following checks only apply on a non-ambient instantiated module declaration.
 	if symbol.Flags&ast.SymbolFlagsValueModule != 0 && !inAmbientContext && isInstantiatedModule(node, c.compilerOptions.ShouldPreserveConstEnums()) {
+		if c.compilerOptions.ErasableSyntaxOnly.IsTrue() {
+			c.error(node, diagnostics.This_syntax_is_not_allowed_when_erasableSyntaxOnly_is_enabled)
+		}
 		if c.compilerOptions.GetIsolatedModules() && ast.GetSourceFileOfNode(node).ExternalModuleIndicator == nil {
 			// This could be loosened a little if needed. The only problem we are trying to avoid is unqualified
 			// references to namespace members declared in other files. But use of namespaces is discouraged anyway,
@@ -5161,6 +5172,9 @@ func (c *Checker) checkImportEqualsDeclaration(node *ast.Node) {
 		return // If we hit an import declaration in an illegal context, just bail out to avoid cascading errors.
 	}
 	c.checkGrammarModifiers(node)
+	if c.compilerOptions.ErasableSyntaxOnly.IsTrue() && ast.IsInternalModuleImportEqualsDeclaration(node) && node.Flags&ast.NodeFlagsAmbient == 0 {
+		c.error(node, diagnostics.This_syntax_is_not_allowed_when_erasableSyntaxOnly_is_enabled)
+	}
 	if ast.IsInternalModuleImportEqualsDeclaration(node) || c.checkExternalImportOrExportDeclaration(node) {
 		c.checkImportBinding(node)
 		c.markLinkedReferences(node, ReferenceHintExportImportEquals, nil, nil)

testdata/baselines/reference/submodule/compiler/erasableSyntaxOnly.errors.txt

@@ -1,36 +1,60 @@
 error TS2318: Cannot find global type 'IterableIterator'.
+index.ts(3,17): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+index.ts(6,11): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+index.ts(10,11): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+index.ts(16,11): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+index.ts(17,15): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+index.ts(22,6): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+index.ts(26,1): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+index.ts(28,12): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
 
 
 !!! error TS2318: Cannot find global type 'IterableIterator'.
-==== index.ts (0 errors) ====
+==== index.ts (8 errors) ====
     class MyClassErr {
         // No parameter properties
         constructor(public foo: string) { }
+                    ~~~~~~~~~~~~~~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
     }
 
     namespace IllegalBecauseInstantiated {
+              ~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
         export const m = 1;
     }
 
     namespace AlsoIllegalBecauseInstantiated {
+              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
         class PrivateClass {
 
         }
     }
 
     namespace IllegalBecauseNestedInstantiated {
+              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
         namespace Nested {
+                  ~~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
             export const m = 1;
         }
     }
 
     enum NotLegalEnum {
+         ~~~~~~~~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
         B = 1
     }
 
     import NoGoodAlias = NotLegalEnum.B;
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
 
     const enum NotLegalConstEnum {
+               ~~~~~~~~~~~~~~~~~
+!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
         C = 2
     }
 

testdata/baselines/reference/submodule/compiler/erasableSyntaxOnly.errors.txt.diff

@@ -4,14 +4,13 @@
  error TS2318: Cannot find global type 'IterableIterator'.
 -commonjs.cts(1,1): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
 -commonjs.cts(2,1): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
--index.ts(3,17): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
--index.ts(6,11): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
--index.ts(10,11): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
--index.ts(16,11): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
--index.ts(17,15): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
--index.ts(22,6): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
--index.ts(26,1): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
--index.ts(28,12): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+ index.ts(3,17): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+ index.ts(6,11): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+ index.ts(10,11): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+@@= skipped -8, +6 lines =@@
+ index.ts(22,6): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+ index.ts(26,1): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
+ index.ts(28,12): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
 -index.ts(67,6): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
 -index.ts(68,6): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
 -index.ts(69,7): error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
@@ -28,55 +27,11 @@
 
  !!! error TS2318: Cannot find global type 'IterableIterator'.
 -==== index.ts (20 errors) ====
-+==== index.ts (0 errors) ====
++==== index.ts (8 errors) ====
      class MyClassErr {
          // No parameter properties
          constructor(public foo: string) { }
--                    ~~~~~~~~~~~~~~~~~~
--!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
-     }
-     
-     namespace IllegalBecauseInstantiated {
--              ~~~~~~~~~~~~~~~~~~~~~~~~~~
--!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
-         export const m = 1;
-     }
-     
-     namespace AlsoIllegalBecauseInstantiated {
--              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
-         class PrivateClass {
-     
-         }
-     }
-     
-     namespace IllegalBecauseNestedInstantiated {
--              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
-         namespace Nested {
--                  ~~~~~~
--!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
-             export const m = 1;
-         }
-     }
-     
-     enum NotLegalEnum {
--         ~~~~~~~~~~~~
--!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
-         B = 1
-     }
-     
-     import NoGoodAlias = NotLegalEnum.B;
--    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
-     
-     const enum NotLegalConstEnum {
--               ~~~~~~~~~~~~~~~~~
--!!! error TS1294: This syntax is not allowed when 'erasableSyntaxOnly' is enabled.
-         C = 2
-     }
-     
-@@= skipped -107, +69 lines =@@
+@@= skipped -99, +87 lines =@@
 
      // Not erasable
      (()=><any>{})();