Fix #50869, only cache calculated type for non-context sensitive parameters

src/compiler/checker.ts

@@ -9696,16 +9696,33 @@ namespace ts {
             }
         }
 
+        function isParameterOfContextSensitiveSignature(symbol: Symbol) {
+            let decl = symbol.valueDeclaration;
+            if (!decl) {
+                return false;
+            }
+            if (isBindingElement(decl)) {
+                decl = walkUpBindingElementsAndPatterns(decl);
+            }
+            if (isParameter(decl)) {
+                return isContextSensitiveFunctionOrObjectLiteralMethod(decl.parent);
+            }
+            return false;
+        }
+
         function getTypeOfVariableOrParameterOrProperty(symbol: Symbol): Type {
             const links = getSymbolLinks(symbol);
             if (!links.type) {
                 const type = getTypeOfVariableOrParameterOrPropertyWorker(symbol);
                 // For a contextually typed parameter it is possible that a type has already
                 // been assigned (in assignTypeToParameterAndFixTypeParameters), and we want
-                // to preserve this type.
-                if (!links.type) {
+                // to preserve this type. In fact, we need to _prefer_ that type, but it won't
+                // be assigned until contextual typing is complete, so we need to defer in
+                // cases where contextual typing may take place.
+                if (!links.type && !isParameterOfContextSensitiveSignature(symbol)) {
                     links.type = type;
                 }
+                return type;
             }
             return links.type;
         }

tests/baselines/reference/completionDetailsOfContextSensitiveParameterNoCrash.baseline

@@ -0,0 +1,52 @@
+[
+  {
+    "marker": {
+      "fileName": "/tests/cases/fourslash/completionDetailsOfContextSensitiveParameterNoCrash.ts",
+      "position": 3101,
+      "name": ""
+    },
+    "quickInfo": {
+      "kind": "parameter",
+      "kindModifiers": "",
+      "textSpan": {
+        "start": 3101,
+        "length": 4
+      },
+      "displayParts": [
+        {
+          "text": "(",
+          "kind": "punctuation"
+        },
+        {
+          "text": "parameter",
+          "kind": "text"
+        },
+        {
+          "text": ")",
+          "kind": "punctuation"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "args",
+          "kind": "parameterName"
+        },
+        {
+          "text": ":",
+          "kind": "punctuation"
+        },
+        {
+          "text": " ",
+          "kind": "space"
+        },
+        {
+          "text": "any",
+          "kind": "keyword"
+        }
+      ],
+      "documentation": []
+    }
+  }
+]

tests/cases/fourslash/completionDetailsOfContextSensitiveParameterNoCrash.ts

@@ -0,0 +1,91 @@
+/// <reference path="fourslash.ts" />
+
+// @strict: true
+////type __ = never;
+////
+////interface CurriedFunction1<T1, R> {
+////    (): CurriedFunction1<T1, R>;
+////    (t1: T1): R;
+////}
+////interface CurriedFunction2<T1, T2, R> {
+////    (): CurriedFunction2<T1, T2, R>;
+////    (t1: T1): CurriedFunction1<T2, R>;
+////    (t1: __, t2: T2): CurriedFunction1<T1, R>;
+////    (t1: T1, t2: T2): R;
+////}
+////
+////interface CurriedFunction3<T1, T2, T3, R> {
+////    (): CurriedFunction3<T1, T2, T3, R>;
+////    (t1: T1): CurriedFunction2<T2, T3, R>;
+////    (t1: __, t2: T2): CurriedFunction2<T1, T3, R>;
+////    (t1: T1, t2: T2): CurriedFunction1<T3, R>;
+////    (t1: __, t2: __, t3: T3): CurriedFunction2<T1, T2, R>;
+////    (t1: T1, t2: __, t3: T3): CurriedFunction1<T2, R>;
+////    (t1: __, t2: T2, t3: T3): CurriedFunction1<T1, R>;
+////    (t1: T1, t2: T2, t3: T3): R;
+////}
+////
+////interface CurriedFunction4<T1, T2, T3, T4, R> {
+////    (): CurriedFunction4<T1, T2, T3, T4, R>;
+////    (t1: T1): CurriedFunction3<T2, T3, T4, R>;
+////    (t1: __, t2: T2): CurriedFunction3<T1, T3, T4, R>;
+////    (t1: T1, t2: T2): CurriedFunction2<T3, T4, R>;
+////    (t1: __, t2: __, t3: T3): CurriedFunction3<T1, T2, T4, R>;
+////    (t1: __, t2: __, t3: T3): CurriedFunction2<T2, T4, R>;
+////    (t1: __, t2: T2, t3: T3): CurriedFunction2<T1, T4, R>;
+////    (t1: T1, t2: T2, t3: T3): CurriedFunction1<T4, R>;
+////    (t1: __, t2: __, t3: __, t4: T4): CurriedFunction3<T1, T2, T3, R>;
+////    (t1: T1, t2: __, t3: __, t4: T4): CurriedFunction2<T2, T3, R>;
+////    (t1: __, t2: T2, t3: __, t4: T4): CurriedFunction2<T1, T3, R>;
+////    (t1: __, t2: __, t3: T3, t4: T4): CurriedFunction2<T1, T2, R>;
+////    (t1: T1, t2: T2, t3: __, t4: T4): CurriedFunction1<T3, R>;
+////    (t1: T1, t2: __, t3: T3, t4: T4): CurriedFunction1<T2, R>;
+////    (t1: __, t2: T2, t3: T3, t4: T4): CurriedFunction1<T1, R>;
+////    (t1: T1, t2: T2, t3: T3, t4: T4): R;
+////}
+////
+////declare var curry: {
+////    <T1, R>(func: (t1: T1) => R, arity?: number): CurriedFunction1<T1, R>;    
+////    <T1, T2, R>(func: (t1: T1, t2: T2) => R, arity?: number): CurriedFunction2<T1, T2, R>;
+////    <T1, T2, T3, R>(func: (t1: T1, t2: T2, t3: T3) => R, arity?: number): CurriedFunction3<T1, T2, T3, R>;
+////    <T1, T2, T3, T4, R>(func: (t1: T1, t2: T2, t3: T3, t4: T4) => R, arity?: number): CurriedFunction4<T1, T2, T3, T4, R>;
+////    (func: (...args: any[]) => any, arity?: number): (...args: any[]) => any;
+////    placeholder: __;
+////};
+////
+////export type StylingFunction = (
+////    keys: (string | false | undefined) | (string | false | undefined)[],
+////    ...rest: unknown[]
+////) => object;
+////
+////declare const getStylingByKeys: (
+////    mergedStyling: object,
+////    keys: (string | false | undefined) | (string | false | undefined)[],
+////    ...args: unknown[]
+////) => object;
+////
+////declare var mergedStyling: object;
+////
+////export const createStyling: CurriedFunction3<
+////    (base16Theme: object) => unknown,
+////    object | undefined,
+////    object | undefined,
+////    StylingFunction
+////> = curry<
+////    (base16Theme: object) => unknown,
+////    object | undefined,
+////    object | undefined,
+////    StylingFunction
+////>(
+////    (
+////        getStylingFromBase16: (base16Theme: object) => unknown,
+////        options: object = {},
+////        themeOrStyling: object = {},
+////        ...args
+////    ): StylingFunction => {
+////        return curry(getStylingByKeys, 2)(mergedStyling, .../**/args);
+////    },
+////    3
+////);
+
+verify.baselineQuickInfo();