Builder errors out on files it's supposed to generate

[Meai1]

> pub run build_runner serve --output=build
[SEVERE] build_web_compilers|ddc on web/index.module:
Error compiling dartdevc module:example|web/index.ddc.js

[error] Target of URI doesn't exist: 'index.jsx.dart'. (/web/index.dart, line 11, col 8)
[error] The function 'r' isn't defined. (/web/index.dart, line 17, col 11)

Please fix all errors before compiling (warnings are okay).
}
[WARNING] build_web_compilers|entrypoint on web/index.dart:

Unable to read example|web/index.ddc.js, check your console or the `.dart_tool/build/generated/example/web/index.ddc.js.errors` log file.
[INFO] Running build completed, took 5.3s
[INFO] Caching finalized dependency graph completed, took 184ms
[SEVERE] Failed after 5.5s
Serving `web` on http://localhost:8080

Dart VM version: 2.0.0-dev.69.5 (Tue Jul 31 15:05:14 2018 +0200) on "linux_x64"

I have attached my full source code because this is weird. I dont see how this can be my fault, it has to be a bug.

example.zip

[jakemac53]

The if (strContent.contains("<template>")) { check is returning false and I don't see that code in the index.dart. I confirmed the ordering of builders is correct though, so if you fix that everything should work.

[Meai1]

@jakemac53 okay I see, the reason why I made such an obvious error is because there seems to be a caching problem and nothing I did changed the behavior of my builder so I got more and more confused.
Try changing the template after it is corrected and no matter how many times I restart pub serve, it wont update the index.jsx.dart when I edit the index.dart.
Surely the purpose of the builder is to keep the output synced with the input file so that must be the bug then.

Change it first to a valid anything with <template> around it: var x = r(""" <template><p>hi</p></template> """);

[jakemac53]

Ah, I see you are reading the file directly with dart:io, in order for the build system to notice changes you need to use the buildStep to read/write files.

Basically, change var strContent = await new File(buildStep.inputId.path).readAsStringSync(); to var strContent = await buildStep.readAsString(buildStep.inputId).

[jakemac53]

This also makes your builder more portable, in can read generated files and run in other environments that don't have dart:io or where the source files live in some other place.

[Meai1]

Cool now it works, thank you. Btw, it was also very confusing for me that print() doesnt seem to work 99% of the time but it does work when I tried to print out the contents after reading it from the buildStep.
That had me perplexed for a long time until I eventually changed all my print()s to log calls. Printing used to work with transformers normally.

[jakemac53]

Printing does work but it logs at the info level which we will usually overwrite to cut down on noise in the logs. You can remove that behavior with the -v flag but you will get a lot of logs in your output.

[natebosch]

We'll also switch print to behave like log.warning instead so those messages stand out.
#1720