`TS8017`

Front-end code SWITCH_CASE

Invalid switch case: a label that is not an integer constant, does not fit the selector, or repeats another; an empty clause with no body below it to share (a trailing one, or one above default:); a body whose end is reachable above a clause with a body, which TypeScript would run on into and WGSL does not (Rule 7.3); or continue in a switch no loop encloses.

The registry text and every compiler message on these pages are the compiler's own English.

Example

"use typeshade"

@fragment
export function main(@location(0) uv: vec2): vec4 {
  let g = 0.
  switch (i32(uv.x * 4.)) {
    case 0: g = 0.25; break
    case 0: g = 0.5; break
    default: g = 1.
  }
  return vec4(g, g, g, 1.)
}

Compiled at build time against the pinned compiler, this program gets:

TS8017 error, line 8: Duplicate switch case 0; each label may appear once.

How to fix it

The same program, corrected. It compiles with no diagnostic.

"use typeshade"

@fragment
export function main(@location(0) uv: vec2): vec4 {
  let g = 0.
  switch (i32(uv.x * 4.)) {
    case 0: g = 0.25; break
    case 1: g = 0.5; break
    default: g = 1.
  }
  return vec4(g, g, g, 1.)
}

The rule this enforces

Rule 7.3 Test: An empty switch case directly above a case with a body is one clause with several selectors (case 0: case 1: is WGSL’s case 0, 1:); an empty case with no case below it or directly above default:, and an empty default: with a case after it, must be refused; a case body must not fall through into the body of a case below it.

Source

Where the compiler raises this code at commit 26de7be8, one line per file:

src/compiler/ts/lower/control.ts:751 (7 sites)

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TS8017

Example

How to fix it

The rule this enforces

See also

Source

`TS8017`