remove uncalled function checks with negations

Author: jonhue

src/compiler/checker.ts

@@ -34538,6 +34538,7 @@ namespace ts {
 
         function checkTestingKnownTruthyCallableOrAwaitableType(condExpr: Expression, type: Type, body?: Statement | Expression) {
             if (!strictNullChecks) return;
+            if (getFalsyFlags(type)) return;
 
             if (getAwaitedTypeOfPromise(type)) {
                 errorAndMaybeSuggestAwait(
@@ -34548,9 +34549,7 @@ namespace ts {
                 return;
             }
 
-            const location = isBinaryExpression(condExpr) ? condExpr.right
-                : isPrefixUnaryExpression(condExpr) ? condExpr.operand
-                : condExpr;
+            const location = isBinaryExpression(condExpr) ? condExpr.right : condExpr;
             if (isBinaryExpression(condExpr) && condExpr.operatorToken.kind === SyntaxKind.BarBarToken) {
                 checkTestingKnownTruthyCallableOrAwaitableType(condExpr.left, type, body);
             }
@@ -34564,17 +34563,12 @@ namespace ts {
                 return;
             }
 
-            const testedType = isPrefixUnaryExpression(condExpr) ? checkExpression(location) : type;
-            if (typeToString(testedType).includes("undefined")) { // maybeTypeOfKind(testedType, TypeFlags.Undefined)
-                return;
-            }
-
             // While it technically should be invalid for any known-truthy value
             // to be tested, we de-scope to functions unrefenced in the block as a
             // heuristic to identify the most common bugs. There are too many
             // false positives for values sourced from type definitions without
             // strictNullChecks otherwise.
-            const callSignatures = getSignaturesOfType(testedType, SignatureKind.Call);
+            const callSignatures = getSignaturesOfType(type, SignatureKind.Call);
             if (callSignatures.length === 0) {
                 return;
             }
@@ -34587,12 +34581,7 @@ namespace ts {
             const isUsed = isBinaryExpression(condExpr.parent) && isFunctionUsedInBinaryExpressionChain(condExpr.parent, testedSymbol)
                 || body && isFunctionUsedInConditionBody(condExpr, body, testedNode, testedSymbol);
             if (!isUsed) {
-                if (getFalsyFlags(type)) {
-                    error(location, Diagnostics.This_condition_will_always_return_false_since_the_function_is_always_defined_Did_you_mean_to_call_it_instead);
-                }
-                else {
-                    error(location, Diagnostics.This_condition_will_always_return_true_since_the_function_is_always_defined_Did_you_mean_to_call_it_instead);
-                }
+                error(location, Diagnostics.This_condition_will_always_return_true_since_the_function_is_always_defined_Did_you_mean_to_call_it_instead);
             }
         }
 

src/compiler/diagnosticMessages.json

@@ -3260,10 +3260,6 @@
         "category": "Error",
         "code": 2801
     },
-    "This condition will always return false since the function is always defined. Did you mean to call it instead?": {
-        "category": "Error",
-        "code": 2802
-    },
 
     "Import declaration '{0}' is using private name '{1}'.": {
         "category": "Error",

src/compiler/moduleSpecifiers.ts

@@ -463,7 +463,7 @@ namespace ts.moduleSpecifiers {
     }
 
     function tryGetModuleNameAsNodeModule({ path, isRedirect }: ModulePath, { getCanonicalFileName, sourceDirectory }: Info, host: ModuleSpecifierResolutionHost, options: CompilerOptions, packageNameOnly?: boolean): string | undefined {
-        if (!host.readFile) {
+        if (!host.fileExists || !host.readFile) {
             return undefined;
         }
         const parts: NodeModulePathParts = getNodeModulePathParts(path)!;
@@ -563,6 +563,7 @@ namespace ts.moduleSpecifiers {
     }
 
     function tryGetAnyFileFromPath(host: ModuleSpecifierResolutionHost, path: string) {
+        if (!host.fileExists) return;
         // We check all js, `node` and `json` extensions in addition to TS, since node module resolution would also choose those over the directory
         const extensions = getSupportedExtensions({ allowJs: true }, [{ extension: "node", isMixedContent: false }, { extension: "json", isMixedContent: false, scriptKind: ScriptKind.JSON }]);
         for (const e of extensions) {

src/compiler/sys.ts

@@ -78,6 +78,9 @@ namespace ts {
 
     /* @internal */
     export function setCustomPollingValues(system: System) {
+        if (!system.getEnvironmentVariable) {
+            return;
+        }
         const pollingIntervalChanged = setCustomLevels("TSC_WATCH_POLLINGINTERVAL", PollingInterval);
         pollingChunkSize = getCustomPollingBasedLevels("TSC_WATCH_POLLINGCHUNKSIZE", defaultChunkLevels) || pollingChunkSize;
         unchangedPollThresholds = getCustomPollingBasedLevels("TSC_WATCH_UNCHANGEDPOLLTHRESHOLDS", defaultChunkLevels) || unchangedPollThresholds;

tests/baselines/reference/truthinessCallExpressionCoercion2.errors.txt

@@ -3,14 +3,15 @@ tests/cases/compiler/truthinessCallExpressionCoercion2.ts(14,10): error TS2774:
 tests/cases/compiler/truthinessCallExpressionCoercion2.ts(41,18): error TS2774: This condition will always return true since the function is always defined. Did you mean to call it instead?
 tests/cases/compiler/truthinessCallExpressionCoercion2.ts(44,9): error TS2774: This condition will always return true since the function is always defined. Did you mean to call it instead?
 tests/cases/compiler/truthinessCallExpressionCoercion2.ts(48,11): error TS2774: This condition will always return true since the function is always defined. Did you mean to call it instead?
+tests/cases/compiler/truthinessCallExpressionCoercion2.ts(65,46): error TS2774: This condition will always return true since the function is always defined. Did you mean to call it instead?
 tests/cases/compiler/truthinessCallExpressionCoercion2.ts(76,5): error TS2774: This condition will always return true since the function is always defined. Did you mean to call it instead?
 tests/cases/compiler/truthinessCallExpressionCoercion2.ts(79,10): error TS2774: This condition will always return true since the function is always defined. Did you mean to call it instead?
 tests/cases/compiler/truthinessCallExpressionCoercion2.ts(99,5): error TS2774: This condition will always return true since the function is always defined. Did you mean to call it instead?
 tests/cases/compiler/truthinessCallExpressionCoercion2.ts(109,9): error TS2774: This condition will always return true since the function is always defined. Did you mean to call it instead?
 tests/cases/compiler/truthinessCallExpressionCoercion2.ts(112,14): error TS2774: This condition will always return true since the function is always defined. Did you mean to call it instead?
 
 
-==== tests/cases/compiler/truthinessCallExpressionCoercion2.ts (10 errors) ====
+==== tests/cases/compiler/truthinessCallExpressionCoercion2.ts (11 errors) ====
     declare class A {
         static from(): string;
     }
@@ -86,6 +87,8 @@ tests/cases/compiler/truthinessCallExpressionCoercion2.ts(112,14): error TS2774:
         // error
         typeof window !== 'undefined' && window.console &&
             ((window.console as any).firebug || (window.console.exception && window.console.table));
+                                                 ~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2774: This condition will always return true since the function is always defined. Did you mean to call it instead?
     }
 
     function checksPropertyAccess() {

tests/baselines/reference/uncalledFunctionChecksInConditional.errors.txt

@@ -1,36 +1,19 @@
-tests/cases/compiler/uncalledFunctionChecksInConditional.ts(5,5): error TS2774: This condition will always return true since the function is always defined. Did you mean to call it instead?
-tests/cases/compiler/uncalledFunctionChecksInConditional.ts(13,6): error TS2802: This condition will always return false since the function is always defined. Did you mean to call it instead?
-tests/cases/compiler/uncalledFunctionChecksInConditional.ts(21,5): error TS2774: This condition will always return true since the function is always defined. Did you mean to call it instead?
-tests/cases/compiler/uncalledFunctionChecksInConditional.ts(21,14): error TS2774: This condition will always return true since the function is always defined. Did you mean to call it instead?
-tests/cases/compiler/uncalledFunctionChecksInConditional.ts(25,5): error TS2774: This condition will always return true since the function is always defined. Did you mean to call it instead?
-tests/cases/compiler/uncalledFunctionChecksInConditional.ts(33,6): error TS2802: This condition will always return false since the function is always defined. Did you mean to call it instead?
+tests/cases/compiler/uncalledFunctionChecksInConditional.ts(4,5): error TS2774: This condition will always return true since the function is always defined. Did you mean to call it instead?
+tests/cases/compiler/uncalledFunctionChecksInConditional.ts(8,5): error TS2774: This condition will always return true since the function is always defined. Did you mean to call it instead?
+tests/cases/compiler/uncalledFunctionChecksInConditional.ts(8,14): error TS2774: This condition will always return true since the function is always defined. Did you mean to call it instead?
+tests/cases/compiler/uncalledFunctionChecksInConditional.ts(12,5): error TS2774: This condition will always return true since the function is always defined. Did you mean to call it instead?
 
 
-==== tests/cases/compiler/uncalledFunctionChecksInConditional.ts (6 errors) ====
+==== tests/cases/compiler/uncalledFunctionChecksInConditional.ts (4 errors) ====
     declare function isFoo(): boolean;
     declare function isBar(): boolean;
-    declare const isUndefinedFoo: () => boolean | undefined;
 
     if (isFoo) {
         ~~~~~
 !!! error TS2774: This condition will always return true since the function is always defined. Did you mean to call it instead?
         // error
     }
 
-    if (isUndefinedFoo) {
-        // no error
-    }
-    
-    if (!isFoo) {
-         ~~~~~
-!!! error TS2802: This condition will always return false since the function is always defined. Did you mean to call it instead?
-        // error
-    }
-    
-    if (!isUndefinedFoo) {
-        // no error
-    }
-    
     if (isFoo || isBar) {
         ~~~~~
 !!! error TS2774: This condition will always return true since the function is always defined. Did you mean to call it instead?
@@ -48,14 +31,4 @@ tests/cases/compiler/uncalledFunctionChecksInConditional.ts(33,6): error TS2802:
     if (isFoo && isFoo()) {
         // no error
     }
-    
-    if (!isFoo || isFoo()) {
-         ~~~~~
-!!! error TS2802: This condition will always return false since the function is always defined. Did you mean to call it instead?
-        // error
-    }
-    
-    if (!isUndefinedFoo || isFoo()) {
-        // no error
-    }
 

tests/baselines/reference/uncalledFunctionChecksInConditional.js

@@ -1,24 +1,11 @@
 //// [uncalledFunctionChecksInConditional.ts]
 declare function isFoo(): boolean;
 declare function isBar(): boolean;
-declare const isUndefinedFoo: () => boolean | undefined;
 
 if (isFoo) {
     // error
 }
 
-if (isUndefinedFoo) {
-    // no error
-}
-
-if (!isFoo) {
-    // error
-}
-
-if (!isUndefinedFoo) {
-    // no error
-}
-
 if (isFoo || isBar) {
     // error
 }
@@ -30,29 +17,12 @@ if (isFoo || isFoo()) {
 if (isFoo && isFoo()) {
     // no error
 }
-
-if (!isFoo || isFoo()) {
-    // error
-}
-
-if (!isUndefinedFoo || isFoo()) {
-    // no error
-}
 
 
 //// [uncalledFunctionChecksInConditional.js]
 if (isFoo) {
     // error
 }
-if (isUndefinedFoo) {
-    // no error
-}
-if (!isFoo) {
-    // error
-}
-if (!isUndefinedFoo) {
-    // no error
-}
 if (isFoo || isBar) {
     // error
 }
@@ -62,9 +32,3 @@ if (isFoo || isFoo()) {
 if (isFoo && isFoo()) {
     // no error
 }
-if (!isFoo || isFoo()) {
-    // error
-}
-if (!isUndefinedFoo || isFoo()) {
-    // no error
-}

tests/baselines/reference/uncalledFunctionChecksInConditional.symbols

@@ -5,33 +5,12 @@ declare function isFoo(): boolean;
 declare function isBar(): boolean;
 >isBar : Symbol(isBar, Decl(uncalledFunctionChecksInConditional.ts, 0, 34))
 
-declare const isUndefinedFoo: () => boolean | undefined;
->isUndefinedFoo : Symbol(isUndefinedFoo, Decl(uncalledFunctionChecksInConditional.ts, 2, 13))
-
 if (isFoo) {
 >isFoo : Symbol(isFoo, Decl(uncalledFunctionChecksInConditional.ts, 0, 0))
 
     // error
 }
 
-if (isUndefinedFoo) {
->isUndefinedFoo : Symbol(isUndefinedFoo, Decl(uncalledFunctionChecksInConditional.ts, 2, 13))
-
-    // no error
-}
-
-if (!isFoo) {
->isFoo : Symbol(isFoo, Decl(uncalledFunctionChecksInConditional.ts, 0, 0))
-
-    // error
-}
-
-if (!isUndefinedFoo) {
->isUndefinedFoo : Symbol(isUndefinedFoo, Decl(uncalledFunctionChecksInConditional.ts, 2, 13))
-
-    // no error
-}
-
 if (isFoo || isBar) {
 >isFoo : Symbol(isFoo, Decl(uncalledFunctionChecksInConditional.ts, 0, 0))
 >isBar : Symbol(isBar, Decl(uncalledFunctionChecksInConditional.ts, 0, 34))
@@ -53,17 +32,3 @@ if (isFoo && isFoo()) {
     // no error
 }
 
-if (!isFoo || isFoo()) {
->isFoo : Symbol(isFoo, Decl(uncalledFunctionChecksInConditional.ts, 0, 0))
->isFoo : Symbol(isFoo, Decl(uncalledFunctionChecksInConditional.ts, 0, 0))
-
-    // error
-}
-
-if (!isUndefinedFoo || isFoo()) {
->isUndefinedFoo : Symbol(isUndefinedFoo, Decl(uncalledFunctionChecksInConditional.ts, 2, 13))
->isFoo : Symbol(isFoo, Decl(uncalledFunctionChecksInConditional.ts, 0, 0))
-
-    // no error
-}
-

tests/baselines/reference/uncalledFunctionChecksInConditional.types

@@ -5,35 +5,12 @@ declare function isFoo(): boolean;
 declare function isBar(): boolean;
 >isBar : () => boolean
 
-declare const isUndefinedFoo: () => boolean | undefined;
->isUndefinedFoo : () => boolean | undefined
-
 if (isFoo) {
 >isFoo : () => boolean
 
     // error
 }
 
-if (isUndefinedFoo) {
->isUndefinedFoo : () => boolean | undefined
-
-    // no error
-}
-
-if (!isFoo) {
->!isFoo : false
->isFoo : () => boolean
-
-    // error
-}
-
-if (!isUndefinedFoo) {
->!isUndefinedFoo : false
->isUndefinedFoo : () => boolean | undefined
-
-    // no error
-}
-
 if (isFoo || isBar) {
 >isFoo || isBar : () => boolean
 >isFoo : () => boolean
@@ -60,23 +37,3 @@ if (isFoo && isFoo()) {
     // no error
 }
 
-if (!isFoo || isFoo()) {
->!isFoo || isFoo() : boolean
->!isFoo : false
->isFoo : () => boolean
->isFoo() : boolean
->isFoo : () => boolean
-
-    // error
-}
-
-if (!isUndefinedFoo || isFoo()) {
->!isUndefinedFoo || isFoo() : boolean
->!isUndefinedFoo : false
->isUndefinedFoo : () => boolean | undefined
->isFoo() : boolean
->isFoo : () => boolean
-
-    // no error
-}
-

tests/cases/compiler/uncalledFunctionChecksInConditional.ts

@@ -2,24 +2,11 @@
 
 declare function isFoo(): boolean;
 declare function isBar(): boolean;
-declare const isUndefinedFoo: () => boolean | undefined;
 
 if (isFoo) {
     // error
 }
 
-if (isUndefinedFoo) {
-    // no error
-}
-
-if (!isFoo) {
-    // error
-}
-
-if (!isUndefinedFoo) {
-    // no error
-}
-
 if (isFoo || isBar) {
     // error
 }
@@ -31,11 +18,3 @@ if (isFoo || isFoo()) {
 if (isFoo && isFoo()) {
     // no error
 }
-
-if (!isFoo || isFoo()) {
-    // error
-}
-
-if (!isUndefinedFoo || isFoo()) {
-    // no error
-}