NNBD preview: Better messaging for non-late uninitialized variable

srawlins · commit-bot@chromium.org · commit 7905e78db21a · 2019-11-18T18:28:23.000Z
Change-Id: Ica0433154f0f72d6f79159a77e0b784bdb1d6f40 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/125561 Reviewed-by: Brian Wilkerson <brianwilkerson@google.com> Commit-Queue: Samuel Rawlins <srawlins@google.com>
diff --git a/pkg/analysis_server/lib/src/edit/nnbd_migration/info_builder.dart b/pkg/analysis_server/lib/src/edit/nnbd_migration/info_builder.dart
@@ -138,6 +138,15 @@ class InfoBuilder {
     } else {
       nullableValue = "a nullable value";
     }
+
+    CompilationUnit unit = node.thisOrAncestorOfType<CompilationUnit>();
+    int lineNumber = unit.lineInfo.getLocation(node.offset).lineNumber;
+
+    if (origin.kind == EdgeOriginKind.uninitializedRead) {
+      return "This variable could not be made 'late' because it is used on "
+          "line $lineNumber, when it is possibly uninitialized";
+    }
+
     if (parent is ArgumentList) {
       return capitalize("$nullableValue is passed as an argument");
     }
@@ -167,8 +176,6 @@ class InfoBuilder {
       return (ancestor is TypedLiteral) ? ancestor : null;
     }
 
-    CompilationUnit unit = node.thisOrAncestorOfType<CompilationUnit>();
-    int lineNumber = unit.lineInfo.getLocation(node.offset).lineNumber;
     FunctionBody functionBody = findFunctionBody();
     if (functionBody != null) {
       AstNode function = functionBody.parent;
diff --git a/pkg/analysis_server/test/src/edit/nnbd_migration/info_builder_test.dart b/pkg/analysis_server/test/src/edit/nnbd_migration/info_builder_test.dart
@@ -409,24 +409,24 @@ void f() {
   test_localVariable() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 void f() {
-  int _v1 = null;
-  int _v2 = _v1;
+  int v1 = null;
+  int v2 = v1;
 }
 ''', migratedContent: '''
 void f() {
-  int? _v1 = null;
-  int? _v2 = _v1;
+  int? v1 = null;
+  int? v2 = v1;
 }
 ''');
-    List<RegionInfo> regions = unit.regions;
+    List<RegionInfo> regions = unit.fixRegions;
     expect(regions, hasLength(2));
     assertRegion(
         region: regions[0],
         offset: 16,
         details: ["This variable is initialized to an explicit 'null'"]);
     assertRegion(
         region: regions[1],
-        offset: 35,
+        offset: 34,
         details: ["This variable is initialized to a nullable value"]);
   }
 
@@ -949,4 +949,29 @@ class C {
     assertDetail(detail: region.details[1], offset: 34, length: 3);
     assertDetail(detail: region.details[2], offset: 70, length: 3);
   }
+
+  test_uninitializedVariable_notLate_uninitializedUse() async {
+    UnitInfo unit = await buildInfoForSingleTestFile('''
+void f() {
+  int v1;
+  if (1 == 2) v1 = 7;
+  g(v1);
+}
+void g(int i) => print(i.isEven);
+''', migratedContent: '''
+void f() {
+  int? v1;
+  if (1 == 2) v1 = 7;
+  g(v1!);
+}
+void g(int i) => print(i.isEven);
+''');
+    List<RegionInfo> regions = unit.fixRegions;
+    expect(regions, hasLength(2));
+    assertRegion(region: regions[0], offset: 16, details: [
+      "This variable could not be made \'late\' because it is used on line 4, "
+          "when it is possibly uninitialized"
+    ]);
+    // regions[1] is the `v1!` fix.
+  }
 }
