Terse mode output from `tsc --build`

Search Terms

tsc --build mode console logging output verbose

Suggestion

Have a middle-ground between verbose and "nothing" when running tsc -b

Use Cases

Initial feedback was that "tsc -b should print nothing by default (if there are no errors)", which is a reasonable first principle to work from. However, it's nice to have some rough idea of what's going on, especially because a tsc -b invocation might take quite a while, depending on what's up to date.

Users today can get more output by running with --verbose, which prints some fairly detailed spew:

message TS6350: Project 'tsconfig.json' is out of date because oldest output 'lib/fetch.js' is older than newest input 'src/fetch.ts'

The verbose output was written primarily as an "Explain why something is happening"; there is no in-between setting that says simply "Explain what is happening".

This is compounded under --watch where tsc -b prints errors, but doesn't print "No errors", so you can't really know if your compilation succeeded or if tsc simply missed a file change.

Proposal

--terse strikes a middle ground between the default (silent) and verbose. Its short name would be -t which doesn't conflict with anything I can think of adding in the near term.

Examples

> tsc -b -t src
message TS6350: 'src/compiler' is up-to-date
message TS6350: 'src/services' is up-to-date
message TS6351: Building 'src/server'...
message TS6351: Building 'src/tests'...
message TS6352: Build completed

> tsc -b -t -w src
message TS6350: All projects are up to date
message TS6351: 'src/compiler' was modified, building...

src/compiler/parser.ts:21:1 - error TS1128: Declaration or statement expected.

21 ?
   ~

message TS6351: 'src/compiler' was modified, building...
message TS6351: Building 'src/server'...
message TS6351: Building 'src/tests'...
message TS6352: All projects are up to date

Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript / JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. new expression-level syntax)

Start at the tsc --build command-line handling and compare the existing default, --verbose, and --watch output paths. Define how a new --terse/-t mode should report project status, builds, completion, and watch-mode success, then validate its output against the examples in the issue.