commit 0d35cf733ee28124af5659d964d5faba08ba7f3e
author Paul Berry <paulberry@google.com> Wed Sep 30 12:03:54 2020 +0000
committer commit-bot@chromium.org <commit-bot@chromium.org> Wed Sep 30 12:03:54 2020 +0000
tree 047115c6558839c60d20063e553fe17f49e76de5
parent 954ba3f31c38ce90ecfe1f6291244d9bcd5ca783

Replace flow analysis's setReachable with setUnreachable.

The setReachable method took a bool indicating whether the new state
should be considered reachable or not, however outside of tests the
value that was passed in was always `false`.  Change to a
`setUnreachable` method taking no arguments.

This should make it easier to transition to a stack representation for
reachability.

Bug: https://github.com/dart-lang/sdk/issues/40009
Change-Id: I16a35ec3d5f44763a60e42f200a3caa619fac118
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/165142
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>

pkg/_fe_analyzer_shared/lib/src/flow_analysis/flow_analysis.dart

diff --git a/pkg/_fe_analyzer_shared/lib/src/flow_analysis/flow_analysis.dart b/pkg/_fe_analyzer_shared/lib/src/flow_analysis/flow_analysis.dart
index b56ed21..7959ff9 100644
--- a/pkg/_fe_analyzer_shared/lib/src/flow_analysis/flow_analysis.dart
+++ b/pkg/_fe_analyzer_shared/lib/src/flow_analysis/flow_analysis.dart
@@ -1525,12 +1525,11 @@
     return _identicalOrNew(this, other, newReachable, newVariableInfo);
   }
 
-  /// Updates the state to indicate whether the control flow path is
-  /// [reachable].
-  FlowModel<Variable, Type> setReachable(bool reachable) {
-    if (this.reachable == reachable) return this;
+  /// Updates the state to indicate that the control flow path is unreachable.
+  FlowModel<Variable, Type> setUnreachable() {
+    if (!reachable) return this;
 
-    return new FlowModel<Variable, Type>.withInfo(reachable, variableInfo);
+    return new FlowModel<Variable, Type>.withInfo(false, variableInfo);
   }
 
   @override
@@ -2547,7 +2546,7 @@
 
   @override
   void booleanLiteral(Expression expression, bool value) {
-    FlowModel<Variable, Type> unreachable = _current.setReachable(false);
+    FlowModel<Variable, Type> unreachable = _current.setUnreachable();
     _storeExpressionInfo(
         expression,
         value
@@ -2676,7 +2675,7 @@
   @override
   void for_bodyBegin(Statement node, Expression condition) {
     ExpressionInfo<Variable, Type> conditionInfo = condition == null
-        ? new ExpressionInfo(_current, _current, _current.setReachable(false))
+        ? new ExpressionInfo(_current, _current, _current.setUnreachable())
         : _expressionEnd(condition);
     _WhileContext<Variable, Type> context =
         new _WhileContext<Variable, Type>(conditionInfo);
@@ -2766,7 +2765,7 @@
     if (context != null) {
       context._breakModel = _join(context._breakModel, _current);
     }
-    _current = _current.setReachable(false);
+    _current = _current.setUnreachable();
   }
 
   @override
@@ -2775,12 +2774,12 @@
     if (context != null) {
       context._continueModel = _join(context._continueModel, _current);
     }
-    _current = _current.setReachable(false);
+    _current = _current.setUnreachable();
   }
 
   @override
   void handleExit() {
-    _current = _current.setReachable(false);
+    _current = _current.setUnreachable();
   }
 
   @override

pkg/_fe_analyzer_shared/test/flow_analysis/flow_analysis_test.dart

diff --git a/pkg/_fe_analyzer_shared/test/flow_analysis/flow_analysis_test.dart b/pkg/_fe_analyzer_shared/test/flow_analysis/flow_analysis_test.dart
index 062bbb5..b7b9be9 100644
--- a/pkg/_fe_analyzer_shared/test/flow_analysis/flow_analysis_test.dart
+++ b/pkg/_fe_analyzer_shared/test/flow_analysis/flow_analysis_test.dart
@@ -2215,24 +2215,22 @@
     var intQVar = _Var('x', _Type('int?'));
     var objectQVar = _Var('x', _Type('Object?'));
     var nullVar = _Var('x', _Type('Null'));
-    group('setReachable', () {
+    group('setUnreachable', () {
       var unreachable = FlowModel<_Var, _Type>(false);
       var reachable = FlowModel<_Var, _Type>(true);
       test('unchanged', () {
-        expect(unreachable.setReachable(false), same(unreachable));
-        expect(reachable.setReachable(true), same(reachable));
+        expect(unreachable.setUnreachable(), same(unreachable));
       });
 
       test('changed', () {
-        void _check(FlowModel<_Var, _Type> initial, bool newReachability) {
-          var s = initial.setReachable(newReachability);
+        void _check(FlowModel<_Var, _Type> initial) {
+          var s = initial.setUnreachable();
           expect(s, isNot(same(initial)));
-          expect(s.reachable, newReachability);
+          expect(s.reachable, false);
           expect(s.variableInfo, same(initial.variableInfo));
         }
 
-        _check(unreachable, true);
-        _check(reachable, false);
+        _check(reachable);
       });
     });
 
@@ -2953,7 +2951,7 @@
       test('reachability', () {
         var h = _Harness();
         var reachable = FlowModel<_Var, _Type>(true);
-        var unreachable = reachable.setReachable(false);
+        var unreachable = reachable.setUnreachable();
         expect(reachable.restrict(h, reachable, Set()), same(reachable));
         expect(reachable.restrict(h, unreachable, Set()), same(unreachable));
         expect(unreachable.restrict(h, unreachable, Set()), same(unreachable));