Not write output file if no content changes

[gdh1995]

TypeScript Version: 2.2.0 / master

Action

# long long ago
cd ~/project
tsc -p .
zip -FS output.zip $(find . -name \*.js)

# after a few days
# I've changed one .ts file
tsc -p .
zip -FS output.zip $(find . -name \*.js)

Expected behavior:
zip will know most .js files keep the same, and only update one .js file corresponding to the modified .ts file.

Actual behavior:
All output .js files are updated by the second tsc -p ., so zip -FS re-updates tons of .js files.

Intention
When I use tsc or tsc -p ., I want it to write into a file only if the output content is different from the old, so the modification times might keep the same, which would be friendly to many tools like diff / make / zip / Beyond Compare.

This refers to #13776 . @mhegazy You said:

Most build systems do check time stamps before calling the compiler

But tsc -p doesn't - what it only does is to compile all .ts files found and update all output files.

And I think: unless I write a very long command line to replace a simple tsconfig.json, I won't be able to keep mtime of unchanged files. The command line would be like this:

TSC_ARGS="--strictNullChecks ----noImplicitReturns --noUnusedLocals --noUnusedParameters --alwaysStrict --removeComments --skipDefaultLibCheck --listEmittedFiles"

dist/%.js: src/%.ts
	tsc $(TSC_ARGS) $@

Too ugly and inconvenient, isn't it?

Update: I find that configurable gulp-typescript / grunt supports this, but they're a bit more than what I just need - I just want one single config file for both VS Code and tsc.

[mhegazy]

This refers to #13776 . @mhegazy You said:

Most build systems do check time stamps before calling the compiler

But tsc -p doesn't - what it only does is to compile all .ts files found and update all output files.

tsc -p is not a build system. it is a compiler, similar to csc, gcc, javac, etc.. your build system, e.g. gulp will not call tsc if it knows it does not need to, i.e. that the outputs are newer than the inputs.

[mhegazy]

And I think: unless I write a very long command line to replace a simple tsconfig.json, I won't be able to keep mtime of unchanged files. The command line would be like this:

I am not sure i understand the issue here. tsc --p is the same as tsc --<arguments in tsconfig.json>. they behave the same, and both will update the file regardless if the output is different or not.

[gdh1995]

Well, if so, I have to say that tsc is nothing more than a toy. Anyway, closed.