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Proper treatment of splicing tuples in array literals - #36861

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Eli Barzilay (elibarzilay) merged 1 commit into
microsoft:masterfrom
elibarzilay:32465
Feb 27, 2020
Merged

Proper treatment of splicing tuples in array literals#36861
Eli Barzilay (elibarzilay) merged 1 commit into
microsoft:masterfrom
elibarzilay:32465

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@elibarzilayEli Barzilay (elibarzilay) commented Feb 18, 2020

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Fixes#32465.

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Eli Barzilay (elibarzilay) commented Feb 18, 2020
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Comment threadsrc/compiler/checker.ts
elibarzilay
Eli Barzilay (elibarzilay) commented Feb 18, 2020
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Comment threadsrc/compiler/checker.ts
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Nathan Shively-Sanders (sandersn) requested changes Feb 20, 2020
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Looks basically right and the baselines improve. I agree with Wesley Wigham (@weswigham) that isTupleLikeType is preferable.

Comment threadsrc/compiler/checker.ts
Comment threadsrc/compiler/checker.ts
Comment threadsrc/compiler/checker.ts Outdated
Comment threadsrc/compiler/checker.ts
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Nathan Shively-Sanders (sandersn) approved these changes Feb 27, 2020
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I think it's a good idea to have the isTupleLike implementation in the PR history but we always Squash & Merge so it should end up as one commit on master anyway.

@elibarzilay
Proper treatment of splicing tuples in array literals
db1c440
Fixesmicrosoft#32465.
After this was done, I continued to extend the implementation to handle
TupleLike types but it'ss broken since JS doesn't allow splicing
TupleLike values into array literals so pulled that out, and instead
keeping it for reference below. (It Includes tests, which are broken
too.)
modified src/compiler/checker.ts
@@ -22268,6 +22268,21 @@ namespace ts {
else hasNonEndingSpreadElement = true;
}
}
+ else if (spreadType && isTupleLikeType(spreadType)) {
+ let i = 0, tupleEltType: Type | undefined;
+ while (tupleEltType = getTypeOfPropertyOfType(spreadType, "" + i as __String)) {
+ elementTypes.push(tupleEltType);
+ i++;
+ }
+ const stringIndexInfo = getIndexInfoOfType(spreadType, IndexKind.String);
+ const numberIndexInfo = getIndexInfoOfType(spreadType, IndexKind.Number);
+ if (stringIndexInfo || numberIndexInfo) {
+ if (stringIndexInfo) elementTypes.push(stringIndexInfo.type);
+ if (numberIndexInfo) elementTypes.push(numberIndexInfo.type);
+ if (i === elementCount - 1) hasEndingSpreadElement = true;
+ else hasNonEndingSpreadElement = true;
+ }
+ }
else {
if (inDestructuringPattern && spreadType) {
// Given the following situation:
new file tests/cases/compiler/spliceTupleLikesWIntegers.ts
@@ -0,0 +1,23 @@
+declare const sb: { [0]: string, [1]: boolean };
+
+let k1: [number, string, boolean];
+k1 = [1, ...sb];
+
+let k2: [number, string, boolean, number];
+k2 = [1, ...sb, 1];
+
+// declare const sb_: [string, ...boolean[]];
+
+// let k3: [number, string, ...boolean[]];
+// k3 = [1, ...sb_];
+
+// declare const sbb_: [string, boolean, ...boolean[]];
+
+// let k4: [number, string, ...boolean[]];
+// k4 = [1, ...sbb_];
+
+// let k5: [number, string, boolean, ...boolean[]];
+// k5 = [1, ...sbb_];
+
+// let k6: [number, string, boolean, boolean, ...boolean[]];
+// k6 = [1, ...sbb_];
new file tests/cases/compiler/spliceTupleLikesWStrings.ts
@@ -0,0 +1,23 @@
+declare const sb: { 0: string, 1: boolean };
+
+let k1: [number, string, boolean];
+k1 = [1, ...sb];
+
+let k2: [number, string, boolean, number];
+k2 = [1, ...sb, 1];
+
+declare const sb_: { 0: string, [s: string]: (boolean|string) };
+
+let k3: [number, string, ...(boolean|string)[]];
+k3 = [1, ...sb_];
+
+declare const sbb_: { 0: string, 1: boolean, [s: string]: (boolean|string) };
+
+let k4: [number, string, boolean, ...(boolean|string)[]];
+k4 = [1, ...sbb_];
+
+// let k5: [number, string, boolean, ...(boolean|string)[]];
+// k5 = [1, ...sbb_];
+
+// let k6: [number, string, boolean, boolean, ...(boolean|string)[]];
+// k6 = [1, ...sbb_];
@elibarzilay
Eli Barzilay (elibarzilay) merged commit e71614a into microsoft:masterFeb 27, 2020
@dandv

Dan Dascalescu (dandv) commented Mar 10, 2020•
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Thank you for the fix. Would it solve this issue as well?

constdate: Date=newDate();constnum=42;// OKconst[a,b]: [Date,number]=[date,num];constargs=[date,num];// Type '(number | Date)[]' is missing the following properties from type '[Date, number]': 0, 1(2739)const[c,d]: [Date,number]=args;

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@sandersn

Nathan Shively-Sanders (sandersn) commented Mar 18, 2020

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No, that's caused by the lack of contextual typing in const args = [date, num] -- the compiler has no way to know that the contents of [date, num] are immutable, so assumes that they're an array instead of a tuple. You can make it explicit with [date, num] as const; we've prototyped making that the default, but it Breaks Everything when we do.

This was referenced May 1, 2020
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@WeiShengv99

WeiSheng_ (WeiShengv99) commented May 18, 2020

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No, that's caused by the lack of contextual typing in const args = [date, num] -- the compiler has no way to know that the contents of [date, num] are immutable, so assumes that they're an array instead of a tuple. You can make it explicit with [date, num] as const; we've prototyped making that the default, but it Breaks Everything when we do.

i dont know what happend in this case , is this the same problem?
https://www.typescriptlang.org/play?ts=3.9.2#code/MYewdgzgLgBApgGzgWzmKAuGBtMBXZAIzgCcAaGfI0gXRgF4cBmCgFjoG4AoL0SWAGYgQDGAAoAhlirFyMQtIKyKwRdTkATNbICUDAHwwA3jwC+3APQWYQkGIB0jsdgCMFR-cQo0sCkzoSEDB80Do6lta2Ym4sHl6o6OFcVjbC0WRxSAlQZEzhQA

@elibarzilay

Eli Barzilay (elibarzilay) commented May 18, 2020

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@GRJser, no -- this was only about splicing into array literals. There is this PR that fixes some spreads in calls and might be relevant for your example.

@btoobtoo mentioned this pull request Aug 10, 2021
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@sandersnNathan Shively-Sanders (sandersn)sandersn approved these changes
@weswighamWesley Wigham (weswigham)Awaiting requested review from weswigham

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typescript can't infer destructuring of array properly

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