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Merge pull request #10396 from Microsoft/fixNestedLoopTypeGuards
Fix nested loop type guards
2 parents 7a9f8c8 + b93cdec commit 4880e7e

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5 files changed

+269
-2
lines changed

5 files changed

+269
-2
lines changed

‎src/compiler/checker.ts

Lines changed: 13 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -8366,13 +8366,18 @@ namespace ts {
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// each antecedent code path.
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const antecedentTypes: Type[] = [];
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let subtypeReduction = false;
8369+
let firstAntecedentType: FlowType;
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flowLoopNodes[flowLoopCount] = flow;
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flowLoopKeys[flowLoopCount] = key;
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flowLoopTypes[flowLoopCount] = antecedentTypes;
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for (const antecedent of flow.antecedents) {
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flowLoopCount++;
8374-
const type = getTypeFromFlowType(getTypeAtFlowNode(antecedent));
8375+
const flowType = getTypeAtFlowNode(antecedent);
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flowLoopCount--;
8377+
if (!firstAntecedentType) {
8378+
firstAntecedentType = flowType;
8379+
}
8380+
const type = getTypeFromFlowType(flowType);
83768381
// If we see a value appear in the cache it is a sign that control flow analysis
83778382
// was restarted and completed by checkExpressionCached. We can simply pick up
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// the resulting type and bail out.
@@ -8395,7 +8400,13 @@ namespace ts {
83958400
break;
83968401
}
83978402
}
8398-
return cache[key] = getUnionType(antecedentTypes, subtypeReduction);
8403+
// The result is incomplete if the first antecedent (the non-looping control flow path)
8404+
// is incomplete.
8405+
const result = getUnionType(antecedentTypes, subtypeReduction);
8406+
if (isIncomplete(firstAntecedentType)) {
8407+
return createFlowType(result, /*incomplete*/ true);
8408+
}
8409+
return cache[key] = result;
83998410
}
84008411

84018412
function isMatchingReferenceDiscriminant(expr: Expression) {

‎tests/baselines/reference/nestedLoopTypeGuards.js

Lines changed: 63 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,63 @@
1+
//// [nestedLoopTypeGuards.ts]
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// Repros from #10378
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function f1() {
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var a: boolean | number | string;
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if (typeof a !== 'boolean') {
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// a is narrowed to "number | string"
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for (var i = 0; i < 1; i++) {
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for (var j = 0; j < 1; j++) {}
10+
if (typeof a === 'string') {
11+
// a is narrowed to "string'
12+
for (var j = 0; j < 1; j++) {
13+
a.length; // Should not error here
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}
15+
}
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}
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}
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}
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function f2() {
21+
var a: string | number;
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if (typeof a === 'string') {
23+
while (1) {
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while (1) {}
25+
if (typeof a === 'string') {
26+
while (1) {
27+
a.length; // Should not error here
28+
}
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}
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}
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}
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}
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//// [nestedLoopTypeGuards.js]
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// Repros from #10378
36+
function f1() {
37+
var a;
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if (typeof a !== 'boolean') {
39+
// a is narrowed to "number | string"
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for (var i = 0; i < 1; i++) {
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for (var j = 0; j < 1; j++) { }
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if (typeof a === 'string') {
43+
// a is narrowed to "string'
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for (var j = 0; j < 1; j++) {
45+
a.length; // Should not error here
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}
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}
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}
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}
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}
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function f2() {
52+
var a;
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if (typeof a === 'string') {
54+
while (1) {
55+
while (1) { }
56+
if (typeof a === 'string') {
57+
while (1) {
58+
a.length; // Should not error here
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}
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}
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}
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}
63+
}

‎tests/baselines/reference/nestedLoopTypeGuards.symbols

Lines changed: 66 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,66 @@
1+
=== tests/cases/compiler/nestedLoopTypeGuards.ts ===
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// Repros from #10378
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function f1() {
5+
>f1 : Symbol(f1, Decl(nestedLoopTypeGuards.ts, 0, 0))
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7+
var a: boolean | number | string;
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>a : Symbol(a, Decl(nestedLoopTypeGuards.ts, 3, 7))
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10+
if (typeof a !== 'boolean') {
11+
>a : Symbol(a, Decl(nestedLoopTypeGuards.ts, 3, 7))
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13+
// a is narrowed to "number | string"
14+
for (var i = 0; i < 1; i++) {
15+
>i : Symbol(i, Decl(nestedLoopTypeGuards.ts, 6, 16))
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>i : Symbol(i, Decl(nestedLoopTypeGuards.ts, 6, 16))
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>i : Symbol(i, Decl(nestedLoopTypeGuards.ts, 6, 16))
18+
19+
for (var j = 0; j < 1; j++) {}
20+
>j : Symbol(j, Decl(nestedLoopTypeGuards.ts, 7, 20), Decl(nestedLoopTypeGuards.ts, 10, 24))
21+
>j : Symbol(j, Decl(nestedLoopTypeGuards.ts, 7, 20), Decl(nestedLoopTypeGuards.ts, 10, 24))
22+
>j : Symbol(j, Decl(nestedLoopTypeGuards.ts, 7, 20), Decl(nestedLoopTypeGuards.ts, 10, 24))
23+
24+
if (typeof a === 'string') {
25+
>a : Symbol(a, Decl(nestedLoopTypeGuards.ts, 3, 7))
26+
27+
// a is narrowed to "string'
28+
for (var j = 0; j < 1; j++) {
29+
>j : Symbol(j, Decl(nestedLoopTypeGuards.ts, 7, 20), Decl(nestedLoopTypeGuards.ts, 10, 24))
30+
>j : Symbol(j, Decl(nestedLoopTypeGuards.ts, 7, 20), Decl(nestedLoopTypeGuards.ts, 10, 24))
31+
>j : Symbol(j, Decl(nestedLoopTypeGuards.ts, 7, 20), Decl(nestedLoopTypeGuards.ts, 10, 24))
32+
33+
a.length; // Should not error here
34+
>a.length : Symbol(String.length, Decl(lib.d.ts, --, --))
35+
>a : Symbol(a, Decl(nestedLoopTypeGuards.ts, 3, 7))
36+
>length : Symbol(String.length, Decl(lib.d.ts, --, --))
37+
}
38+
}
39+
}
40+
}
41+
}
42+
43+
function f2() {
44+
>f2 : Symbol(f2, Decl(nestedLoopTypeGuards.ts, 16, 1))
45+
46+
var a: string | number;
47+
>a : Symbol(a, Decl(nestedLoopTypeGuards.ts, 19, 7))
48+
49+
if (typeof a === 'string') {
50+
>a : Symbol(a, Decl(nestedLoopTypeGuards.ts, 19, 7))
51+
52+
while (1) {
53+
while (1) {}
54+
if (typeof a === 'string') {
55+
>a : Symbol(a, Decl(nestedLoopTypeGuards.ts, 19, 7))
56+
57+
while (1) {
58+
a.length; // Should not error here
59+
>a.length : Symbol(String.length, Decl(lib.d.ts, --, --))
60+
>a : Symbol(a, Decl(nestedLoopTypeGuards.ts, 19, 7))
61+
>length : Symbol(String.length, Decl(lib.d.ts, --, --))
62+
}
63+
}
64+
}
65+
}
66+
}

‎tests/baselines/reference/nestedLoopTypeGuards.types

Lines changed: 96 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,96 @@
1+
=== tests/cases/compiler/nestedLoopTypeGuards.ts ===
2+
// Repros from #10378
3+
4+
function f1() {
5+
>f1 : () => void
6+
7+
var a: boolean | number | string;
8+
>a : string | number | boolean
9+
10+
if (typeof a !== 'boolean') {
11+
>typeof a !== 'boolean' : boolean
12+
>typeof a : string
13+
>a : string | number | boolean
14+
>'boolean' : "boolean"
15+
16+
// a is narrowed to "number | string"
17+
for (var i = 0; i < 1; i++) {
18+
>i : number
19+
>0 : number
20+
>i < 1 : boolean
21+
>i : number
22+
>1 : number
23+
>i++ : number
24+
>i : number
25+
26+
for (var j = 0; j < 1; j++) {}
27+
>j : number
28+
>0 : number
29+
>j < 1 : boolean
30+
>j : number
31+
>1 : number
32+
>j++ : number
33+
>j : number
34+
35+
if (typeof a === 'string') {
36+
>typeof a === 'string' : boolean
37+
>typeof a : string
38+
>a : string | number
39+
>'string' : "string"
40+
41+
// a is narrowed to "string'
42+
for (var j = 0; j < 1; j++) {
43+
>j : number
44+
>0 : number
45+
>j < 1 : boolean
46+
>j : number
47+
>1 : number
48+
>j++ : number
49+
>j : number
50+
51+
a.length; // Should not error here
52+
>a.length : number
53+
>a : string
54+
>length : number
55+
}
56+
}
57+
}
58+
}
59+
}
60+
61+
function f2() {
62+
>f2 : () => void
63+
64+
var a: string | number;
65+
>a : string | number
66+
67+
if (typeof a === 'string') {
68+
>typeof a === 'string' : boolean
69+
>typeof a : string
70+
>a : string | number
71+
>'string' : "string"
72+
73+
while (1) {
74+
>1 : number
75+
76+
while (1) {}
77+
>1 : number
78+
79+
if (typeof a === 'string') {
80+
>typeof a === 'string' : boolean
81+
>typeof a : string
82+
>a : string
83+
>'string' : "string"
84+
85+
while (1) {
86+
>1 : number
87+
88+
a.length; // Should not error here
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>a.length : number
90+
>a : string
91+
>length : number
92+
}
93+
}
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}
95+
}
96+
}

‎tests/cases/compiler/nestedLoopTypeGuards.ts

Lines changed: 31 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,31 @@
1+
// Repros from #10378
2+
3+
function f1() {
4+
var a: boolean | number | string;
5+
if (typeof a !== 'boolean') {
6+
// a is narrowed to "number | string"
7+
for (var i = 0; i < 1; i++) {
8+
for (var j = 0; j < 1; j++) {}
9+
if (typeof a === 'string') {
10+
// a is narrowed to "string'
11+
for (var j = 0; j < 1; j++) {
12+
a.length; // Should not error here
13+
}
14+
}
15+
}
16+
}
17+
}
18+
19+
function f2() {
20+
var a: string | number;
21+
if (typeof a === 'string') {
22+
while (1) {
23+
while (1) {}
24+
if (typeof a === 'string') {
25+
while (1) {
26+
a.length; // Should not error here
27+
}
28+
}
29+
}
30+
}
31+
}

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