The error "Object is possibly null or undefined" is ambiguous. (#49797)

* added object name to TS2571, 2531, 2532 and 2533

* updated localized diagnostic messages

* updated baseline to fit diagnostic message change

* Revert "updated localized diagnostic messages"

This reverts commit 738cf09.

* specialized the error to EntityNameExpression

* updated baseline to fit new changes

* added multiline undefined access test

* added TS18049 - value cannot be used here

* adjusted baseline

* corrected a small linting issue

* Update error numbers after merge from main

Co-authored-by: Nathan Shively-Sanders <[email protected]>

Author: norech

src/compiler/checker.ts

@@ -29172,11 +29172,30 @@ namespace ts {
         }
 
         function reportObjectPossiblyNullOrUndefinedError(node: Node, facts: TypeFacts) {
-            error(node, facts & TypeFacts.IsUndefined ? facts & TypeFacts.IsNull ?
-                Diagnostics.Object_is_possibly_null_or_undefined :
-                Diagnostics.Object_is_possibly_undefined :
-                Diagnostics.Object_is_possibly_null
-            );
+            const nodeText = isEntityNameExpression(node) ? entityNameToString(node) : undefined;
+            if (node.kind === SyntaxKind.NullKeyword) {
+                error(node, Diagnostics.The_value_0_cannot_be_used_here, "null");
+                return;
+            }
+            if (nodeText !== undefined && nodeText.length < 100) {
+                if (isIdentifier(node) && nodeText === "undefined") {
+                    error(node, Diagnostics.The_value_0_cannot_be_used_here, "undefined");
+                    return;
+                }
+                error(node, facts & TypeFacts.IsUndefined ? facts & TypeFacts.IsNull ?
+                    Diagnostics._0_is_possibly_null_or_undefined :
+                    Diagnostics._0_is_possibly_undefined :
+                    Diagnostics._0_is_possibly_null,
+                    nodeText
+                );
+            }
+            else {
+                error(node, facts & TypeFacts.IsUndefined ? facts & TypeFacts.IsNull ?
+                    Diagnostics.Object_is_possibly_null_or_undefined :
+                    Diagnostics.Object_is_possibly_undefined :
+                    Diagnostics.Object_is_possibly_null
+                );
+            }
         }
 
         function reportCannotInvokePossiblyNullOrUndefinedError(node: Node, facts: TypeFacts) {
@@ -29193,6 +29212,13 @@ namespace ts {
             reportError: (node: Node, facts: TypeFacts) => void
         ): Type {
             if (strictNullChecks && type.flags & TypeFlags.Unknown) {
+                if (isEntityNameExpression(node)) {
+                    const nodeText = entityNameToString(node);
+                    if (nodeText.length < 100) {
+                        error(node, Diagnostics._0_is_of_type_unknown, nodeText);
+                        return errorType;
+                    }
+                }
                 error(node, Diagnostics.Object_is_of_type_unknown);
                 return errorType;
             }
@@ -29212,6 +29238,17 @@ namespace ts {
         function checkNonNullNonVoidType(type: Type, node: Node): Type {
             const nonNullType = checkNonNullType(type, node);
             if (nonNullType.flags & TypeFlags.Void) {
+                if (isEntityNameExpression(node)) {
+                    const nodeText = entityNameToString(node);
+                    if (isIdentifier(node) && nodeText === "undefined") {
+                        error(node, Diagnostics.The_value_0_cannot_be_used_here, nodeText);
+                        return nonNullType;
+                    }
+                    if (nodeText.length < 100) {
+                        error(node, Diagnostics._0_is_possibly_undefined, nodeText);
+                        return nonNullType;
+                    }
+                }
                 error(node, Diagnostics.Object_is_possibly_undefined);
             }
             return nonNullType;

src/compiler/diagnosticMessages.json

@@ -7497,5 +7497,25 @@
     "Properties with the 'accessor' modifier are only available when targeting ECMAScript 2015 and higher.": {
         "category": "Error",
         "code": 18045
+    },
+    "'{0}' is of type 'unknown'.": {
+        "category": "Error",
+        "code": 18046
+    },
+    "'{0}' is possibly 'null'.": {
+        "category": "Error",
+        "code": 18047
+    },
+    "'{0}' is possibly 'undefined'.": {
+        "category": "Error",
+        "code": 18048
+    },
+    "'{0}' is possibly 'null' or 'undefined'.": {
+        "category": "Error",
+        "code": 18049
+    },
+    "The value '{0}' cannot be used here.": {
+        "category": "Error",
+        "code": 18050
     }
 }

tests/baselines/reference/arithmeticOperatorWithNullValueAndInvalidOperands.errors.txt

@@ -1,7 +1,7 @@
-tests/cases/compiler/binaryArithmatic1.ts(1,13): error TS2531: Object is possibly 'null'.
+tests/cases/compiler/binaryArithmatic1.ts(1,13): error TS18050: The value 'null' cannot be used here.
 
 
 ==== tests/cases/compiler/binaryArithmatic1.ts (1 errors) ====
     var v = 4 | null;
                 ~~~~
-!!! error TS2531: Object is possibly 'null'.
+!!! error TS18050: The value 'null' cannot be used here.

tests/baselines/reference/arithmeticOperatorWithNullValueAndValidOperands.errors.txt

@@ -1,7 +1,7 @@
-tests/cases/compiler/binaryArithmatic2.ts(1,13): error TS2532: Object is possibly 'undefined'.
+tests/cases/compiler/binaryArithmatic2.ts(1,13): error TS18050: The value 'undefined' cannot be used here.
 
 
 ==== tests/cases/compiler/binaryArithmatic2.ts (1 errors) ====
     var v = 4 | undefined;
                 ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+!!! error TS18050: The value 'undefined' cannot be used here.

tests/baselines/reference/arithmeticOperatorWithOnlyNullValueOrUndefinedValue.errors.txt

@@ -1,10 +1,10 @@
-tests/cases/compiler/binaryArithmatic3.ts(1,9): error TS2532: Object is possibly 'undefined'.
-tests/cases/compiler/binaryArithmatic3.ts(1,21): error TS2532: Object is possibly 'undefined'.
+tests/cases/compiler/binaryArithmatic3.ts(1,9): error TS18050: The value 'undefined' cannot be used here.
+tests/cases/compiler/binaryArithmatic3.ts(1,21): error TS18050: The value 'undefined' cannot be used here.
 
 
 ==== tests/cases/compiler/binaryArithmatic3.ts (2 errors) ====
     var v = undefined | undefined;
             ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+!!! error TS18050: The value 'undefined' cannot be used here.
                         ~~~~~~~~~
-!!! error TS2532: Object is possibly 'undefined'.
+!!! error TS18050: The value 'undefined' cannot be used here.