Merge pull request #25251 from Microsoft/betterAlwaysTrueFalseErrors

Better "always true/false" errors
microsoft · Jun 28, 2018 · 950593b · 950593b
2 parents 16f045b + 704cd7b
commit 950593b
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Showing 40 changed files with 1,500 additions and 739 deletions.
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -20884,7 +20884,31 @@ namespace ts {
             }
 
             function reportOperatorError() {
-                error(errorNode || operatorToken, Diagnostics.Operator_0_cannot_be_applied_to_types_1_and_2, tokenToString(operatorToken.kind), typeToString(leftType), typeToString(rightType));
+                let err = chainDiagnosticMessages(
+                    /*elaboration*/ undefined,
+                    Diagnostics.Operator_0_cannot_be_applied_to_types_1_and_2,
+                    tokenToString(operatorToken.kind),
+                    typeToString(leftType),
+                    typeToString(rightType)
+                );
+                err = giveBetterPrimaryError(err);
+
+                diagnostics.add(createDiagnosticForNodeFromMessageChain(
+                    errorNode || operatorToken,
+                    err
+                ));
+            }
+
+            function giveBetterPrimaryError(elaboration: DiagnosticMessageChain) {
+                switch (operatorToken.kind) {
+                    case SyntaxKind.EqualsEqualsEqualsToken:
+                    case SyntaxKind.EqualsEqualsToken:
+                        return chainDiagnosticMessages(elaboration, Diagnostics.The_types_of_these_values_indicate_that_this_condition_will_always_be_0, "false");
+                    case SyntaxKind.ExclamationEqualsEqualsToken:
+                    case SyntaxKind.ExclamationEqualsToken:
+                        return chainDiagnosticMessages(elaboration, Diagnostics.The_types_of_these_values_indicate_that_this_condition_will_always_be_0, "true");
+                    }
+                return elaboration;
             }
         }
 

diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
@@ -1252,6 +1252,10 @@
         "category": "Error",
         "code": 2366
     },
+    "The types of these values indicate that this condition will always be '{0}'.": {
+        "category": "Error",
+        "code": 2367
+    },
     "Type parameter name cannot be '{0}'.": {
         "category": "Error",
         "code": 2368

diff --git a/src/testRunner/unittests/tsserverProjectSystem.ts b/src/testRunner/unittests/tsserverProjectSystem.ts
@@ -4997,7 +4997,7 @@ namespace ts.projectSystem {
             assert.isTrue(error2Result.length === 0);
         });
 
-        it("should report semanitc errors for loose JS files with '// @ts-check' and skipLibCheck=true", () => {
+        it("should report semantic errors for loose JS files with '// @ts-check' and skipLibCheck=true", () => {
             const jsFile = {
                 path: "/a/jsFile.js",
                 content: `
@@ -5016,10 +5016,10 @@ namespace ts.projectSystem {
             );
             const errorResult = <protocol.Diagnostic[]>session.executeCommand(getErrRequest).response;
             assert.isTrue(errorResult.length === 1);
-            assert.equal(errorResult[0].code, Diagnostics.Operator_0_cannot_be_applied_to_types_1_and_2.code);
+            assert.equal(errorResult[0].code, Diagnostics.The_types_of_these_values_indicate_that_this_condition_will_always_be_0.code);
         });
 
-        it("should report semanitc errors for configured js project with '// @ts-check' and skipLibCheck=true", () => {
+        it("should report semantic errors for configured js project with '// @ts-check' and skipLibCheck=true", () => {
             const jsconfigFile = {
                 path: "/a/jsconfig.json",
                 content: "{}"
@@ -5043,10 +5043,10 @@ namespace ts.projectSystem {
             );
             const errorResult = <protocol.Diagnostic[]>session.executeCommand(getErrRequest).response;
             assert.isTrue(errorResult.length === 1);
-            assert.equal(errorResult[0].code, Diagnostics.Operator_0_cannot_be_applied_to_types_1_and_2.code);
+            assert.equal(errorResult[0].code, Diagnostics.The_types_of_these_values_indicate_that_this_condition_will_always_be_0.code);
         });
 
-        it("should report semanitc errors for configured js project with checkJs=true and skipLibCheck=true", () => {
+        it("should report semantic errors for configured js project with checkJs=true and skipLibCheck=true", () => {
             const jsconfigFile = {
                 path: "/a/jsconfig.json",
                 content: JSON.stringify({
@@ -5072,7 +5072,7 @@ namespace ts.projectSystem {
             );
             const errorResult = <protocol.Diagnostic[]>session.executeCommand(getErrRequest).response;
             assert.isTrue(errorResult.length === 1);
-            assert.equal(errorResult[0].code, Diagnostics.Operator_0_cannot_be_applied_to_types_1_and_2.code);
+            assert.equal(errorResult[0].code, Diagnostics.The_types_of_these_values_indicate_that_this_condition_will_always_be_0.code);
         });
     });
 

diff --git a/tests/baselines/reference/api/tsserverlibrary.d.ts b/tests/baselines/reference/api/tsserverlibrary.d.ts
@@ -5151,6 +5151,7 @@ declare namespace ts {
         The_left_hand_side_of_an_assignment_expression_must_be_a_variable_or_a_property_access: DiagnosticMessage;
         Operator_0_cannot_be_applied_to_types_1_and_2: DiagnosticMessage;
         Function_lacks_ending_return_statement_and_return_type_does_not_include_undefined: DiagnosticMessage;
+        The_types_of_these_values_indicate_that_this_condition_will_always_be_0: DiagnosticMessage;
         Type_parameter_name_cannot_be_0: DiagnosticMessage;
         A_parameter_property_is_only_allowed_in_a_constructor_implementation: DiagnosticMessage;
         A_rest_parameter_must_be_of_an_array_type: DiagnosticMessage;

diff --git a/tests/baselines/reference/capturedLetConstInLoop5.errors.txt b/tests/baselines/reference/capturedLetConstInLoop5.errors.txt
@@ -1,5 +1,7 @@
-tests/cases/compiler/capturedLetConstInLoop5.ts(174,13): error TS2365: Operator '==' cannot be applied to types '0' and '1'.
-tests/cases/compiler/capturedLetConstInLoop5.ts(229,13): error TS2365: Operator '==' cannot be applied to types '0' and '1'.
+tests/cases/compiler/capturedLetConstInLoop5.ts(174,13): error TS2367: The types of these values indicate that this condition will always be 'false'.
+  Operator '==' cannot be applied to types '0' and '1'.
+tests/cases/compiler/capturedLetConstInLoop5.ts(229,13): error TS2367: The types of these values indicate that this condition will always be 'false'.
+  Operator '==' cannot be applied to types '0' and '1'.
 
 
 ==== tests/cases/compiler/capturedLetConstInLoop5.ts (2 errors) ====
@@ -178,7 +180,8 @@ tests/cases/compiler/capturedLetConstInLoop5.ts(229,13): error TS2365: Operator
             (() => x + v);
             if (x == 1) {
                 ~~~~~~
-!!! error TS2365: Operator '==' cannot be applied to types '0' and '1'.
+!!! error TS2367: The types of these values indicate that this condition will always be 'false'.
+!!! error TS2367:   Operator '==' cannot be applied to types '0' and '1'.
                 return;
             }
         }
@@ -235,7 +238,8 @@ tests/cases/compiler/capturedLetConstInLoop5.ts(229,13): error TS2365: Operator
             (() => x + y + v);
             if (x == 1) {
                 ~~~~~~
-!!! error TS2365: Operator '==' cannot be applied to types '0' and '1'.
+!!! error TS2367: The types of these values indicate that this condition will always be 'false'.
+!!! error TS2367:   Operator '==' cannot be applied to types '0' and '1'.
                 return;
             }
         }

diff --git a/tests/baselines/reference/capturedLetConstInLoop5_ES6.errors.txt b/tests/baselines/reference/capturedLetConstInLoop5_ES6.errors.txt
@@ -1,5 +1,7 @@
-tests/cases/compiler/capturedLetConstInLoop5_ES6.ts(174,13): error TS2365: Operator '==' cannot be applied to types '0' and '1'.
-tests/cases/compiler/capturedLetConstInLoop5_ES6.ts(229,13): error TS2365: Operator '==' cannot be applied to types '0' and '1'.
+tests/cases/compiler/capturedLetConstInLoop5_ES6.ts(174,13): error TS2367: The types of these values indicate that this condition will always be 'false'.
+  Operator '==' cannot be applied to types '0' and '1'.
+tests/cases/compiler/capturedLetConstInLoop5_ES6.ts(229,13): error TS2367: The types of these values indicate that this condition will always be 'false'.
+  Operator '==' cannot be applied to types '0' and '1'.
 
 
 ==== tests/cases/compiler/capturedLetConstInLoop5_ES6.ts (2 errors) ====
@@ -178,7 +180,8 @@ tests/cases/compiler/capturedLetConstInLoop5_ES6.ts(229,13): error TS2365: Opera
             (() => x + v);
             if (x == 1) {
                 ~~~~~~
-!!! error TS2365: Operator '==' cannot be applied to types '0' and '1'.
+!!! error TS2367: The types of these values indicate that this condition will always be 'false'.
+!!! error TS2367:   Operator '==' cannot be applied to types '0' and '1'.
                 return;
             }
         }
@@ -235,7 +238,8 @@ tests/cases/compiler/capturedLetConstInLoop5_ES6.ts(229,13): error TS2365: Opera
             (() => x + y + v);
             if (x == 1) {
                 ~~~~~~
-!!! error TS2365: Operator '==' cannot be applied to types '0' and '1'.
+!!! error TS2367: The types of these values indicate that this condition will always be 'false'.
+!!! error TS2367:   Operator '==' cannot be applied to types '0' and '1'.
                 return;
             }
         }

diff --git a/tests/baselines/reference/capturedLetConstInLoop6.errors.txt b/tests/baselines/reference/capturedLetConstInLoop6.errors.txt
@@ -1,7 +1,11 @@
-tests/cases/compiler/capturedLetConstInLoop6.ts(147,9): error TS2365: Operator '==' cannot be applied to types '0' and '1'.
-tests/cases/compiler/capturedLetConstInLoop6.ts(150,9): error TS2365: Operator '==' cannot be applied to types '0' and '2'.
-tests/cases/compiler/capturedLetConstInLoop6.ts(194,9): error TS2365: Operator '==' cannot be applied to types '0' and '1'.
-tests/cases/compiler/capturedLetConstInLoop6.ts(197,9): error TS2365: Operator '==' cannot be applied to types '0' and '2'.
+tests/cases/compiler/capturedLetConstInLoop6.ts(147,9): error TS2367: The types of these values indicate that this condition will always be 'false'.
+  Operator '==' cannot be applied to types '0' and '1'.
+tests/cases/compiler/capturedLetConstInLoop6.ts(150,9): error TS2367: The types of these values indicate that this condition will always be 'false'.
+  Operator '==' cannot be applied to types '0' and '2'.
+tests/cases/compiler/capturedLetConstInLoop6.ts(194,9): error TS2367: The types of these values indicate that this condition will always be 'false'.
+  Operator '==' cannot be applied to types '0' and '1'.
+tests/cases/compiler/capturedLetConstInLoop6.ts(197,9): error TS2367: The types of these values indicate that this condition will always be 'false'.
+  Operator '==' cannot be applied to types '0' and '2'.
 
 
 ==== tests/cases/compiler/capturedLetConstInLoop6.ts (4 errors) ====
@@ -153,12 +157,14 @@ tests/cases/compiler/capturedLetConstInLoop6.ts(197,9): error TS2365: Operator '
         (() => x);
         if (x == 1) {
             ~~~~~~
-!!! error TS2365: Operator '==' cannot be applied to types '0' and '1'.
+!!! error TS2367: The types of these values indicate that this condition will always be 'false'.
+!!! error TS2367:   Operator '==' cannot be applied to types '0' and '1'.
             break;
         }
         if (x == 2) {
             ~~~~~~
-!!! error TS2365: Operator '==' cannot be applied to types '0' and '2'.
+!!! error TS2367: The types of these values indicate that this condition will always be 'false'.
+!!! error TS2367:   Operator '==' cannot be applied to types '0' and '2'.
             continue;
         }
     }
@@ -204,12 +210,14 @@ tests/cases/compiler/capturedLetConstInLoop6.ts(197,9): error TS2365: Operator '
         (() => x + y);
         if (x == 1) {
             ~~~~~~
-!!! error TS2365: Operator '==' cannot be applied to types '0' and '1'.
+!!! error TS2367: The types of these values indicate that this condition will always be 'false'.
+!!! error TS2367:   Operator '==' cannot be applied to types '0' and '1'.
             break;
         }
         if (x == 2) {
             ~~~~~~
-!!! error TS2365: Operator '==' cannot be applied to types '0' and '2'.
+!!! error TS2367: The types of these values indicate that this condition will always be 'false'.
+!!! error TS2367:   Operator '==' cannot be applied to types '0' and '2'.
             continue;
         }
     }

diff --git a/tests/baselines/reference/capturedLetConstInLoop6_ES6.errors.txt b/tests/baselines/reference/capturedLetConstInLoop6_ES6.errors.txt
@@ -1,7 +1,11 @@
-tests/cases/compiler/capturedLetConstInLoop6_ES6.ts(147,9): error TS2365: Operator '==' cannot be applied to types '0' and '1'.
-tests/cases/compiler/capturedLetConstInLoop6_ES6.ts(150,9): error TS2365: Operator '==' cannot be applied to types '0' and '2'.
-tests/cases/compiler/capturedLetConstInLoop6_ES6.ts(194,9): error TS2365: Operator '==' cannot be applied to types '0' and '1'.
-tests/cases/compiler/capturedLetConstInLoop6_ES6.ts(197,9): error TS2365: Operator '==' cannot be applied to types '0' and '2'.
+tests/cases/compiler/capturedLetConstInLoop6_ES6.ts(147,9): error TS2367: The types of these values indicate that this condition will always be 'false'.
+  Operator '==' cannot be applied to types '0' and '1'.
+tests/cases/compiler/capturedLetConstInLoop6_ES6.ts(150,9): error TS2367: The types of these values indicate that this condition will always be 'false'.
+  Operator '==' cannot be applied to types '0' and '2'.
+tests/cases/compiler/capturedLetConstInLoop6_ES6.ts(194,9): error TS2367: The types of these values indicate that this condition will always be 'false'.
+  Operator '==' cannot be applied to types '0' and '1'.
+tests/cases/compiler/capturedLetConstInLoop6_ES6.ts(197,9): error TS2367: The types of these values indicate that this condition will always be 'false'.
+  Operator '==' cannot be applied to types '0' and '2'.
 
 
 ==== tests/cases/compiler/capturedLetConstInLoop6_ES6.ts (4 errors) ====
@@ -153,12 +157,14 @@ tests/cases/compiler/capturedLetConstInLoop6_ES6.ts(197,9): error TS2365: Operat
         (() => x);
         if (x == 1) {
             ~~~~~~
-!!! error TS2365: Operator '==' cannot be applied to types '0' and '1'.
+!!! error TS2367: The types of these values indicate that this condition will always be 'false'.
+!!! error TS2367:   Operator '==' cannot be applied to types '0' and '1'.
             break;
         }
         if (x == 2) {
             ~~~~~~
-!!! error TS2365: Operator '==' cannot be applied to types '0' and '2'.
+!!! error TS2367: The types of these values indicate that this condition will always be 'false'.
+!!! error TS2367:   Operator '==' cannot be applied to types '0' and '2'.
             continue;
         }
     }
@@ -204,12 +210,14 @@ tests/cases/compiler/capturedLetConstInLoop6_ES6.ts(197,9): error TS2365: Operat
         (() => x + y);
         if (x == 1) {
             ~~~~~~
-!!! error TS2365: Operator '==' cannot be applied to types '0' and '1'.
+!!! error TS2367: The types of these values indicate that this condition will always be 'false'.
+!!! error TS2367:   Operator '==' cannot be applied to types '0' and '1'.
             break;
         }
         if (x == 2) {
             ~~~~~~
-!!! error TS2365: Operator '==' cannot be applied to types '0' and '2'.
+!!! error TS2367: The types of these values indicate that this condition will always be 'false'.
+!!! error TS2367:   Operator '==' cannot be applied to types '0' and '2'.
             continue;
         }
     }