Consider collapsing multiple repeated type-related error messages when in --pretty · Issue #23393 · microsoft/TypeScript (original) (raw)

Search Terms: error message pretty collapsing

The TS team started a few conversations in TSConf 2018 about making TypeScript error messages more friendly to newcomers. One good first one to approach could be repeated, near-identical errors around the same type.

Code

For example, if a type is missing multiple times in the same file:

let a: MissingType; let b: MissingType; // .. let c: MissingType;

Expected behavior:

In a debatably perfect world, TypeScript could give a single error message for the repeated class of error:

src/index.ts Error TS2304: Cannot find name 'MissingType'.

1   let a: MissingType;
           ~~~~~~~~~~~
2   let b: MissingType;
           ~~~~~~~~~~~
4   let c: MissingType;
           ~~~~~~~~~~~

Actual behavior:

Three separate errors.

Perhaps a post-processing step in --pretty mode that receives all of a file's errors and smooshes them down when it can?

Some open questions:

• Which classes of errors would be in this bucket?
  • Example: TS2304 missing type if the type is the same
  • Example: TS2339 property does not exist if the type and property are the same
• How should this look?
  • As suggested above, which is similar to existing --pretty output but with line+column removed?
  • If there are a many of the same error, should the output truncate with a summary?