5974851c24
## Current Behavior
There is no dependency between the inferred `typecheck` and `build`
tasks. Depending on their run order, this can result in duplicated
processing (type-checking, `.d.ts` generation). Given there's no
explicit dependency, the order would be non-deterministic.
Additionally, when `outDir` is set in the tsconfig files, it's used
as-is in the currently inferred outputs for `typecheck`. This can result
in extra files being cached for the task.
## Expected Behavior
For optimum performance, the inferred `typecheck` task should depend on
the `build` task. The `typecheck` task's outputs should be more granular
so that only the relevant files (declaration files and declaration map
files if enabled) are cached.
### Explanation
Consider a typical setup with specific tsconfig file for files with
different concerns:
- tsconfig.lib.json: TS configuration for the library runtime files
- tsconfig.spec.json: TS configuration for the unit test files
- tsconfig.json: TS solution configuration, a solution file that
references the specific config files above
When running `tsc -b tsconfig.lib.json --verbose` (build), we can see
how the `tsconfig.lib.json` TS project is built:
```bash
Projects in this build:
* tsconfig.lib.json
Project 'tsconfig.lib.json' is out of date because output file 'dist/tsconfig.lib.tsbuildinfo' does not exist
Building project '<workspace root>/packages/pkg1/tsconfig.lib.json'...
```
After that, if we run `tsc -b tsconfig.json --emitDeclarationOnly
--verbose` (typecheck), we'll see how the `tsc` output for
`tsconfig.lib.json` is reused:
```bash
Projects in this build:
* tsconfig.lib.json
* tsconfig.spec.json
* tsconfig.json
Project 'tsconfig.lib.json' is up to date because newest input 'src/lib/file.ts' is older than output 'dist/tsconfig.lib.tsbuildinfo'
Project 'tsconfig.spec.json' is out of date because output file 'out-tsc/jest/tsconfig.spec.tsbuildinfo' does not exist
Building project '<workspace root>/packages/pkg1/tsconfig.spec.json'...
```
The relevant bit above is `Project 'tsconfig.lib.json' is up to date
because newest input 'src/lib/file.ts' is older than output
'dist/tsconfig.lib.tsbuildinfo'`. Because the initial `build` task
already typechecks and produces `.d.ts` files for the
`tsconfig.lib.json`, when the `typecheck` task runs, `tsc` identifies
that the outputs for that config files were already produced and can be
reused.
If we were to run the tasks in the inverse order, the results would be
different:
```bash
> npx tsc -b tsconfig.json --emitDeclarationOnly --verbose
Projects in this build:
* tsconfig.lib.json
* tsconfig.spec.json
* tsconfig.json
Project 'tsconfig.lib.json' is out of date because output file 'dist/tsconfig.lib.tsbuildinfo' does not exist
Building project '<workspace root>/packages/pkg1/tsconfig.lib.json'...
Project 'tsconfig.spec.json' is out of date because output file 'out-tsc/jest/tsconfig.spec.tsbuildinfo' does not exist
Building project '<workspace root>/packages/pkg1/tsconfig.spec.json'...
> npx tsc -b tsconfig.lib.json --verbose
Projects in this build:
* tsconfig.lib.json
Project 'tsconfig.lib.json' is out of date because buildinfo file 'dist/tsconfig.lib.tsbuildinfo' indicates there is change in compilerOptions
Building project '<workspace root>/packages/pkg1/tsconfig.lib.json'...
```
Note how when the `build` task is run, `tsc` identifies that there was a
change in `compilerOptions` (`--emitDeclarationOnly`) and it requires
building the project. This is because the `typecheck` task only
generates declaration files and the `build` task must also emit the
transpiled `.js` files.
### Benchmark
Running those two different flows in a simple (non-Nx) project with a TS
configuration structure like the one mentioned above and with 5000 TS
files split in half for runtime and test files yields the following:
```bash
hyperfine -r 5 -p "rm -rf dist out-tsc" \
-n "build => typecheck" "npx tsc -b tsconfig.lib.json && npx tsc -b --emitDeclarationOnly" \
-n "typecheck => build" "npx tsc -b tsconfig.json --emitDeclarationOnly && npx tsc -b tsconfig.lib.json"
Benchmark 1: build => typecheck
Time (mean ± σ): 6.832 s ± 0.094 s [User: 11.361 s, System: 1.060 s]
Range (min … max): 6.734 s … 6.985 s 5 runs
Benchmark 2: typecheck => build
Time (mean ± σ): 8.789 s ± 0.015 s [User: 14.817 s, System: 1.267 s]
Range (min … max): 8.771 s … 8.812 s 5 runs
Summary
build => typecheck ran
1.29 ± 0.02 times faster than typecheck => build
```
## Related Issue(s)
Fixes #
{{links}}
Nx: Smart Monorepos · Fast CI
Nx is a build system, optimized for monorepos, with plugins for popular frameworks and tools and advanced CI capabilities including caching and distribution.
This package is a JavaScript/TypeScript plugin for Nx.
{{content}}