[cfe] Add test for exhaustiveness of != null

Change-Id: I04a34cf6f806a634a2290d8d3c68bbb724b7ebcc
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/421183
Commit-Queue: Johnni Winther <[email protected]>
Reviewed-by: Paul Berry <[email protected]>

Author: johnniwinther

pkg/_fe_analyzer_shared/test/exhaustiveness/data/not_null.dart

@@ -0,0 +1,14 @@
+// Copyright (c) 2025, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+method(int? i) => /*
+ checkingOrder={int?,int,Null},
+ error=non-exhaustive:int();null,
+ subtypes={int,Null},
+ type=int?
+*/
+    switch (i) {
+      == null /*space=?*/ => null,
+      != null /*space=?*/ => i,
+    };

pkg/front_end/testcases/patterns/exhaustiveness/not_null.dart

@@ -0,0 +1,9 @@
+// Copyright (c) 2025, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+method(int? i) => switch (i) {
+  == null => null,
+  != null => i,
+  _ => null,
+};

pkg/front_end/testcases/patterns/exhaustiveness/not_null.dart.strong.expect

@@ -0,0 +1,32 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+static method method(core::int? i) → dynamic
+  return block {
+    core::int? #t1;
+    final synthesized core::int? #0#0 = i;
+    synthesized core::bool #0#2;
+    synthesized core::bool #0#2#isSet = false;
+    #L1:
+    {
+      {
+        if(#0#2#isSet ?{core::bool} #0#2{core::bool} : let final dynamic #t2 = #0#2#isSet = true in #0#2 = #0#0 == null) {
+          #t1 = null;
+          break #L1;
+        }
+      }
+      {
+        if(!(#0#2#isSet ?{core::bool} #0#2{core::bool} : let final dynamic #t3 = #0#2#isSet = true in #0#2 = #0#0{core::int} == null)) {
+          #t1 = i{core::int};
+          break #L1;
+        }
+      }
+      {
+        if(true) {
+          #t1 = null;
+          break #L1;
+        }
+      }
+    }
+  } =>#t1;

pkg/front_end/testcases/patterns/exhaustiveness/not_null.dart.strong.modular.expect

@@ -0,0 +1,32 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+static method method(core::int? i) → dynamic
+  return block {
+    core::int? #t1;
+    final synthesized core::int? #0#0 = i;
+    synthesized core::bool #0#2;
+    synthesized core::bool #0#2#isSet = false;
+    #L1:
+    {
+      {
+        if(#0#2#isSet ?{core::bool} #0#2{core::bool} : let final dynamic #t2 = #0#2#isSet = true in #0#2 = #0#0 == null) {
+          #t1 = null;
+          break #L1;
+        }
+      }
+      {
+        if(!(#0#2#isSet ?{core::bool} #0#2{core::bool} : let final dynamic #t3 = #0#2#isSet = true in #0#2 = #0#0{core::int} == null)) {
+          #t1 = i{core::int};
+          break #L1;
+        }
+      }
+      {
+        if(true) {
+          #t1 = null;
+          break #L1;
+        }
+      }
+    }
+  } =>#t1;

pkg/front_end/testcases/patterns/exhaustiveness/not_null.dart.strong.outline.expect

@@ -0,0 +1,6 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+static method method(core::int? i) → dynamic
+  ;

pkg/front_end/testcases/patterns/exhaustiveness/not_null.dart.strong.transformed.expect

@@ -0,0 +1,32 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+static method method(core::int? i) → dynamic
+  return block {
+    core::int? #t1;
+    final synthesized core::int? #0#0 = i;
+    synthesized core::bool #0#2;
+    synthesized core::bool #0#2#isSet = false;
+    #L1:
+    {
+      {
+        if(#0#2#isSet ?{core::bool} #0#2{core::bool} : let final core::bool #t2 = #0#2#isSet = true in #0#2 = #0#0 == null) {
+          #t1 = null;
+          break #L1;
+        }
+      }
+      {
+        if(!(#0#2#isSet ?{core::bool} #0#2{core::bool} : let final core::bool #t3 = #0#2#isSet = true in #0#2 = #0#0{core::int} == null)) {
+          #t1 = i{core::int};
+          break #L1;
+        }
+      }
+      {
+        if(true) {
+          #t1 = null;
+          break #L1;
+        }
+      }
+    }
+  } =>#t1;

pkg/front_end/testcases/patterns/exhaustiveness/not_null.dart.textual_outline.expect

@@ -0,0 +1,5 @@
+method(int? i) => switch (i) {
+      == null => null,
+      != null => i,
+      _ => null,
+    };

pkg/front_end/testcases/patterns/exhaustiveness/not_null.dart.textual_outline_modelled.expect

@@ -0,0 +1,5 @@
+method(int? i) => switch (i) {
+      == null => null,
+      != null => i,
+      _ => null,
+    };