microsoft / microsoft/TypeScript
Quadratic check time for diamond-shaped interface inheritance graphs
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描述
## Search Terms
hasBaseType, interface inheritance performance, diamond-shaped interface inheritance, base type traversal, quadratic check time
## Version & Regression Information
This reproduces on TypeScript 6.0.3 and on current `main` before the proposed fix.
Tested current `main` commit:
```text
7964e22f2b85f16e520f0e902c7fd7b6f0c15416
```
## Code
The repro is an interface-only diamond-shaped inheritance graph. Each interface extends up to 8 previous interfaces.
Full repro
```ts
// @strict: true
// @noEmit: true
interface I0 {
p0_0: number;
}
interface I1 extends I0 {
p1_0: number;
}
interface I2 extends I1, I0 {
p2_0: number;
}
interface I3 extends I2, I1, I0 {
p3_0: number;
}
interface I4 extends I3, I2, I1, I0 {
p4_0: number;
}
interface I5 extends I4, I3, I2, I1, I0 {
p5_0: number;
}
interface I6 extends I5, I4, I3, I2, I1, I0 {
p6_0: number;
}
interface I7 extends I6, I5, I4, I3, I2, I1, I0 {
p7_0: number;
}
interface I8 extends I7, I6, I5, I4, I3, I2, I1, I0 {
p8_0: number;
}
interface I9 extends I8, I7, I6, I5, I4, I3, I2, I1 {
p9_0: number;
}
interface I10 extends I9, I8, I7, I6, I5, I4, I3, I2 {
p10_0: number;
}
interface I11 extends I10, I9, I8, I7, I6, I5, I4, I3 {
p11_0: number;
}
interface I12 extends I11, I10, I9, I8, I7, I6, I5, I4 {
p12_0: number;
}
interface I13 extends I12, I11, I10, I9, I8, I7, I6, I5 {
p13_0: number;
}
interface I14 extends I13, I12, I11, I10, I9, I8, I7, I6 {
p14_0: number;
}
interface I15 extends I14, I13, I12, I11, I10, I9, I8, I7 {
p15_0: number;
}
interface I16 extends I15, I14, I13, I12, I11, I10, I9, I8 {
p16_0: number;
}
interface I17 extends I16, I15, I14, I13, I12, I11, I10, I9 {
p17_0: number;
}
interface I18 extends I17, I16, I15, I14, I13, I12, I11, I10 {
p18_0: number;
}
interface I19 extends I18, I17, I16, I15, I14, I13, I12, I11 {
p19_0: number;
}
interface I20 extends I19, I18, I17, I16, I15, I14, I13, I12 {
p20_0: number;
}
interface I21 extends I20, I19, I18, I17, I16, I15, I14, I13 {
p21_0: number;
}
interface I22 extends I21, I20, I19, I18, I17, I16, I15, I14 {
p22_0: number;
}
interface I23 extends I22, I21, I20, I19, I18, I17, I16, I15 {
p23_0: number;
}
interface I24 extends I23, I22, I21, I20, I19, I18, I17, I16 {
p24_0: number;
}
interface I25 extends I24, I23, I22, I21, I20, I19, I18, I17 {
p25_0: number;
}
interface I26 extends I25, I24, I23, I22, I21, I20, I19, I18 {
p26_0: number;
}
interface I27 extends I26, I25, I24, I23, I22, I21, I20, I19 {
p27_0: number;
}
interface I28 extends I27, I26, I25, I24, I23, I22, I21, I20 {
p28_0: number;
}
interface I29 extends I28, I27, I26, I25, I24, I23, I22, I21 {
p29_0: number;
}
interface I30 extends I29, I28, I27, I26, I25, I24, I23, I22 {
p30_0: number;
}
interface I31 extends I30, I29, I28, I27, I26, I25, I24, I23 {
p31_0: number;
}
declare const value: I31;
value.p0_0;
```
## Actual behavior
Before the fix, compiling the repro above timed out after 30 seconds.
The hotspot is `hasBaseType`, which recursively walks `getBaseTypes(target)` and can revisit the same reachable base-type subgraphs many times during one query.
## Expected behavior
The checker should avoid revisiting the same base-type subgraph during a single `hasBaseType` query.
With a per-call `seen` set in `hasBaseType`, the same repro completes quickly:
```text
Check time: 0.01s
Total time: 0.13s
```
## Proposed fix
The fix is to keep a per-call `Set` inside `hasBaseType` and skip already visited class/interface/reference/intersection nodes.
```ts
function hasBaseType(type: Type, checkBase: Type | undefined) {
if (!checkBase) {
return false;
}
const seen = new Set();
return check(type);
function check(type: Type): boolean {
if (getObjectFlags(type) & (ObjectFlags.ClassOrInterface | ObjectFlags.Reference)) {
const target = getTargetType(type) as InterfaceType;
if (target === checkBase) {
return true;
}
if (seen.has(target)) {
return false;
}
seen.add(target);
return some(getBaseTypes(target), check);
}
else if (type.flags & TypeFlags.Intersection) {
if (seen.has(type)) {
return false;
}
seen.add(type);
return some((type as IntersectionType).types, check);
}
return false;
}
}
```
I have pushed a branch with the proposed fix and regression test here:
```text
https://github.com/canonic-epicure/TypeScript/tree/fix-has-base-type-seen
```
Commit:
```text
51938c85a396151a93ac0101f94c66a55dfafa14
```
## Additional information
The branch contains:
- the `hasBaseType` fix;
- the compiler regression test shown above;
- updated baselines.
Validation run:
```bash
npx hereby local
npx hereby runtests --tests=interfaceExtendsDiamondPerformance
npx hereby runtests --tests='interfaceThatIndirectlyInheritsFromItself|interfaceThatInheritsFromItself|circularBaseTypes|infinitelyExpandingBaseTypes1'
npx hereby runtests --runner=compiler
```
Result:
```text
89845 passing
```
I can open a PR with the fix if this is considered appropriate for the JS-based TypeScript repository maintenance policy.
贡献指南
从这里开始
- 先读完整个 Issue,再读项目的贡献指南。
- 在 Issue 下留言说明你要接手 —— 这能避免两个人做同样的事。
- Fork 仓库,在一个分支上完成修改。
- 提交 Pull Request,并在描述里引用这个 Issue 编号。
调研方向
从 hasBaseType 的实现开始,并将提议的 branch 修复与名为 interfaceExtendsDiamondPerformance 的编译器回归测试进行比较。运行此处列出的验证命令,尤其是该测试和循环基类型测试。完成的标准是 diamond 复现能够快速完成,同时不会导致现有编译器测试套件出现回归;提议的修复和 branch 已经存在。
由索引模型根据 Issue 内容生成。
评估
- 技术栈
- typescript
- 领域
- compilers, performance
- Issue 类型
- 缺陷
- 难度
- 4/5
- 预计耗时
- 3-5 天
- 活跃度
- 冷清
- 描述清晰度
- 描述清楚
- 新手友好度
- 35/100