[dart2js] Fix codegen/variance_subtype_cast_test

- We don't need to use the type to check for the presence and absence
  of a check, '._as(' is sufficient.
- Added ability of Absent/Present checker to use regexps

Change-Id: Ie1ecaafcaa3d5121b19ffd77564d800e0c72bd4f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/147020
Reviewed-by: Joshua Litt <joshualitt@google.com>
Commit-Queue: Stephen Adams <sra@google.com>

Author: rakudrama

tests/compiler/dart2js/codegen/variance_subtype_cast_test.dart

@@ -14,7 +14,8 @@ class LegacyCovariant<T> {
 foo(param) {
   LegacyCovariant<num> c = LegacyCovariant<num>();
   (c as LegacyCovariant<int>).method();
-  // present: 'LegacyCovariant_int._as'
+  // present: '._as('
+  // present: /(legacy_)?LegacyCovariant_(legacy_)?int._as/
 }
 """;
 
@@ -25,7 +26,7 @@ class LegacyCovariant<T> {
 foo(param) {
   LegacyCovariant<num> c = LegacyCovariant<num>();
   (c as LegacyCovariant<Object>).method();
-  // absent: 'LegacyCovariant_Object._as'
+  // absent: '._as('
 }
 """;
 
@@ -36,7 +37,8 @@ class Covariant<out T> {
 foo(param) {
   Covariant<num> c = Covariant<num>();
   (c as Covariant<int>).method();
-  // present: 'Covariant_int._as'
+  // present: '._as('
+  // present: /(legacy_)?Covariant_(legacy_)?int._as/
 }
 """;
 
@@ -47,7 +49,7 @@ class Covariant<out T> {
 foo(param) {
   Covariant<num> c = Covariant<num>();
   (c as Covariant<Object>).method();
-  // absent: 'Covariant_Object._as'
+  // absent: '._as('
 }
 """;
 
@@ -58,7 +60,8 @@ class Contravariant<in T> {
 foo(param) {
   Contravariant<num> c = Contravariant<num>();
   (c as Contravariant<Object>).method();
-  // present: 'Contravariant_Object._as'
+  // present: '._as('
+  // present: /(legacy_)?Contravariant_(legacy_)?Object._as/
 }
 """;
 
@@ -69,7 +72,7 @@ class Contravariant<in T> {
 foo(param) {
   Contravariant<num> c = Contravariant<num>();
   (c as Contravariant<int>).method();
-  // absent: 'Contravariant_int._as'
+  // absent: '._as('
 }
 """;
 
@@ -80,7 +83,8 @@ class Invariant<inout T> {
 foo(param) {
   Invariant<num> i = Invariant<num>();
   (i as Invariant<Object>).method();
-  // present: 'Invariant_Object._as'
+  // present: '._as('
+  // present: /(legacy_)?Invariant_(legacy_)?Object._as/
 }
 """;
 
@@ -91,7 +95,8 @@ class Invariant<inout T> {
 foo(param) {
   Invariant<num> i = Invariant<num>();
   (i as Invariant<int>).method();
-  // present: 'Invariant_int._as'
+  // present: '._as('
+  // present: /(legacy_)?Invariant_(legacy_)?int._as/
 }
 """;
 
@@ -102,7 +107,7 @@ class Invariant<inout T> {
 foo(param) {
   Invariant<num> i = Invariant<num>();
   (i as Invariant<num>).method();
-  // absent: 'Invariant_num._as'
+  // absent: '._as('
 }
 """;
 

tests/compiler/dart2js/helpers/compiler_helper.dart

@@ -220,7 +220,8 @@ checkerForAbsentPresent(String test) {
     }
     for (Match match in matches) {
       String directive = match.group(1);
-      String pattern = match.groups([2, 3]).where((s) => s != null).single;
+      Pattern pattern = match.groups([2, 3, 4]).where((s) => s != null).single;
+      if (match.group(4) != null) pattern = RegExp(pattern);
       if (directive == 'present') {
         Expect.isTrue(generated.contains(pattern),
             "Cannot find '$pattern' in:\n$generated");
@@ -236,5 +237,6 @@ checkerForAbsentPresent(String test) {
 }
 
 RegExp _directivePattern = new RegExp(
-    //      \1                     \2        \3
-    r'''// *(present|absent): *(?:"([^"]*)"|'([^'']*)')''', multiLine: true);
+    //      \1                     \2        \3         \4
+    r'''// *(present|absent): *(?:"([^"]*)"|'([^'']*)'|/(.*)/)''',
+    multiLine: true);