Fix higher order inference on indexed access types (microsoft#20165)

zfkl · Dec 21, 2017 · 7ad0d7b · 7ad0d7b
1 parent 00450f0
commit 7ad0d7b
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Showing 5 changed files with 171 additions and 1 deletion.
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -11400,7 +11400,7 @@ namespace ts {
                         return;
                     }
                 }
-                else if (getObjectFlags(source) & ObjectFlags.Reference && getObjectFlags(target) & ObjectFlags.Reference && (<TypeReference>source).target === (<TypeReference>target).target) {
+                if (getObjectFlags(source) & ObjectFlags.Reference && getObjectFlags(target) & ObjectFlags.Reference && (<TypeReference>source).target === (<TypeReference>target).target) {
                     // If source and target are references to the same generic type, infer from type arguments
                     const sourceTypes = (<TypeReference>source).typeArguments || emptyArray;
                     const targetTypes = (<TypeReference>target).typeArguments || emptyArray;

diff --git a/tests/baselines/reference/indexedAccessCanBeHighOrder.js b/tests/baselines/reference/indexedAccessCanBeHighOrder.js
@@ -0,0 +1,21 @@
+//// [indexedAccessCanBeHighOrder.ts]
+declare function get<U, Y extends keyof U>(x: U, y: Y): U[Y];
+declare function find<T, K extends keyof T>(o: T[K]): [T, K];
+
+function impl<A, B extends keyof A>(a: A, b: B) {
+    const item = get(a, b);
+    return find(item);
+}
+
+const o = {x: 42};
+const r = impl(o, "x");
+r[0][r[1]] = o[r[1]];
+
+//// [indexedAccessCanBeHighOrder.js]
+function impl(a, b) {
+    var item = get(a, b);
+    return find(item);
+}
+var o = { x: 42 };
+var r = impl(o, "x");
+r[0][r[1]] = o[r[1]];
diff --git a/tests/baselines/reference/indexedAccessCanBeHighOrder.symbols b/tests/baselines/reference/indexedAccessCanBeHighOrder.symbols
@@ -0,0 +1,63 @@
+=== tests/cases/compiler/indexedAccessCanBeHighOrder.ts ===
+declare function get<U, Y extends keyof U>(x: U, y: Y): U[Y];
+>get : Symbol(get, Decl(indexedAccessCanBeHighOrder.ts, 0, 0))
+>U : Symbol(U, Decl(indexedAccessCanBeHighOrder.ts, 0, 21))
+>Y : Symbol(Y, Decl(indexedAccessCanBeHighOrder.ts, 0, 23))
+>U : Symbol(U, Decl(indexedAccessCanBeHighOrder.ts, 0, 21))
+>x : Symbol(x, Decl(indexedAccessCanBeHighOrder.ts, 0, 43))
+>U : Symbol(U, Decl(indexedAccessCanBeHighOrder.ts, 0, 21))
+>y : Symbol(y, Decl(indexedAccessCanBeHighOrder.ts, 0, 48))
+>Y : Symbol(Y, Decl(indexedAccessCanBeHighOrder.ts, 0, 23))
+>U : Symbol(U, Decl(indexedAccessCanBeHighOrder.ts, 0, 21))
+>Y : Symbol(Y, Decl(indexedAccessCanBeHighOrder.ts, 0, 23))
+
+declare function find<T, K extends keyof T>(o: T[K]): [T, K];
+>find : Symbol(find, Decl(indexedAccessCanBeHighOrder.ts, 0, 61))
+>T : Symbol(T, Decl(indexedAccessCanBeHighOrder.ts, 1, 22))
+>K : Symbol(K, Decl(indexedAccessCanBeHighOrder.ts, 1, 24))
+>T : Symbol(T, Decl(indexedAccessCanBeHighOrder.ts, 1, 22))
+>o : Symbol(o, Decl(indexedAccessCanBeHighOrder.ts, 1, 44))
+>T : Symbol(T, Decl(indexedAccessCanBeHighOrder.ts, 1, 22))
+>K : Symbol(K, Decl(indexedAccessCanBeHighOrder.ts, 1, 24))
+>T : Symbol(T, Decl(indexedAccessCanBeHighOrder.ts, 1, 22))
+>K : Symbol(K, Decl(indexedAccessCanBeHighOrder.ts, 1, 24))
+
+function impl<A, B extends keyof A>(a: A, b: B) {
+>impl : Symbol(impl, Decl(indexedAccessCanBeHighOrder.ts, 1, 61))
+>A : Symbol(A, Decl(indexedAccessCanBeHighOrder.ts, 3, 14))
+>B : Symbol(B, Decl(indexedAccessCanBeHighOrder.ts, 3, 16))
+>A : Symbol(A, Decl(indexedAccessCanBeHighOrder.ts, 3, 14))
+>a : Symbol(a, Decl(indexedAccessCanBeHighOrder.ts, 3, 36))
+>A : Symbol(A, Decl(indexedAccessCanBeHighOrder.ts, 3, 14))
+>b : Symbol(b, Decl(indexedAccessCanBeHighOrder.ts, 3, 41))
+>B : Symbol(B, Decl(indexedAccessCanBeHighOrder.ts, 3, 16))
+
+    const item = get(a, b);
+>item : Symbol(item, Decl(indexedAccessCanBeHighOrder.ts, 4, 9))
+>get : Symbol(get, Decl(indexedAccessCanBeHighOrder.ts, 0, 0))
+>a : Symbol(a, Decl(indexedAccessCanBeHighOrder.ts, 3, 36))
+>b : Symbol(b, Decl(indexedAccessCanBeHighOrder.ts, 3, 41))
+
+    return find(item);
+>find : Symbol(find, Decl(indexedAccessCanBeHighOrder.ts, 0, 61))
+>item : Symbol(item, Decl(indexedAccessCanBeHighOrder.ts, 4, 9))
+}
+
+const o = {x: 42};
+>o : Symbol(o, Decl(indexedAccessCanBeHighOrder.ts, 8, 5))
+>x : Symbol(x, Decl(indexedAccessCanBeHighOrder.ts, 8, 11))
+
+const r = impl(o, "x");
+>r : Symbol(r, Decl(indexedAccessCanBeHighOrder.ts, 9, 5))
+>impl : Symbol(impl, Decl(indexedAccessCanBeHighOrder.ts, 1, 61))
+>o : Symbol(o, Decl(indexedAccessCanBeHighOrder.ts, 8, 5))
+
+r[0][r[1]] = o[r[1]];
+>r : Symbol(r, Decl(indexedAccessCanBeHighOrder.ts, 9, 5))
+>0 : Symbol(0)
+>r : Symbol(r, Decl(indexedAccessCanBeHighOrder.ts, 9, 5))
+>1 : Symbol(1)
+>o : Symbol(o, Decl(indexedAccessCanBeHighOrder.ts, 8, 5))
+>r : Symbol(r, Decl(indexedAccessCanBeHighOrder.ts, 9, 5))
+>1 : Symbol(1)
+
diff --git a/tests/baselines/reference/indexedAccessCanBeHighOrder.types b/tests/baselines/reference/indexedAccessCanBeHighOrder.types
@@ -0,0 +1,75 @@
+=== tests/cases/compiler/indexedAccessCanBeHighOrder.ts ===
+declare function get<U, Y extends keyof U>(x: U, y: Y): U[Y];
+>get : <U, Y extends keyof U>(x: U, y: Y) => U[Y]
+>U : U
+>Y : Y
+>U : U
+>x : U
+>U : U
+>y : Y
+>Y : Y
+>U : U
+>Y : Y
+
+declare function find<T, K extends keyof T>(o: T[K]): [T, K];
+>find : <T, K extends keyof T>(o: T[K]) => [T, K]
+>T : T
+>K : K
+>T : T
+>o : T[K]
+>T : T
+>K : K
+>T : T
+>K : K
+
+function impl<A, B extends keyof A>(a: A, b: B) {
+>impl : <A, B extends keyof A>(a: A, b: B) => [A, B]
+>A : A
+>B : B
+>A : A
+>a : A
+>A : A
+>b : B
+>B : B
+
+    const item = get(a, b);
+>item : A[B]
+>get(a, b) : A[B]
+>get : <U, Y extends keyof U>(x: U, y: Y) => U[Y]
+>a : A
+>b : B
+
+    return find(item);
+>find(item) : [A, B]
+>find : <T, K extends keyof T>(o: T[K]) => [T, K]
+>item : A[B]
+}
+
+const o = {x: 42};
+>o : { x: number; }
+>{x: 42} : { x: number; }
+>x : number
+>42 : 42
+
+const r = impl(o, "x");
+>r : [{ x: number; }, "x"]
+>impl(o, "x") : [{ x: number; }, "x"]
+>impl : <A, B extends keyof A>(a: A, b: B) => [A, B]
+>o : { x: number; }
+>"x" : "x"
+
+r[0][r[1]] = o[r[1]];
+>r[0][r[1]] = o[r[1]] : number
+>r[0][r[1]] : number
+>r[0] : { x: number; }
+>r : [{ x: number; }, "x"]
+>0 : 0
+>r[1] : "x"
+>r : [{ x: number; }, "x"]
+>1 : 1
+>o[r[1]] : number
+>o : { x: number; }
+>r[1] : "x"
+>r : [{ x: number; }, "x"]
+>1 : 1
+
diff --git a/tests/cases/compiler/indexedAccessCanBeHighOrder.ts b/tests/cases/compiler/indexedAccessCanBeHighOrder.ts
@@ -0,0 +1,11 @@
+declare function get<U, Y extends keyof U>(x: U, y: Y): U[Y];
+declare function find<T, K extends keyof T>(o: T[K]): [T, K];
+
+function impl<A, B extends keyof A>(a: A, b: B) {
+    const item = get(a, b);
+    return find(item);
+}
+
+const o = {x: 42};
+const r = impl(o, "x");
+r[0][r[1]] = o[r[1]];