fix messaging upon error

Cakefile

@@ -11,6 +11,7 @@ helpers                   = require './lib/coffeescript/helpers'
 util                      = require 'util'
 process                   = require 'process'
 
+{ BuildDeps }             = require './build-support/build-deps'
 { CompileSources }        = require './build-support/compile-sources'
 { JisonParser }           = require './build-support/parser'
 { setupStyler }           = require './build-support/colors'
@@ -83,8 +84,10 @@ buildParser = ->
   # (1) cache parser build
   #   (1.1) cache on grammar.coffee [DONE]
   #   (1.2) cache on jison dep [DONE (kinda--uses package-lock.json)]
-  # (2) cache file compilation
+  # (2) cache file compilation [DONE]
   # (3) make source maps work for errors in the coffeescript compiler!
+  buildDepsTask = new BuildDeps
+  await buildDepsTask.cachedExecute console
   parserTask = new JisonParser
   await parserTask.cachedExecute console
 
@@ -95,11 +98,9 @@ buildExceptParser = ->
     coffeeSource = path.join 'src', file
     jsOut = path.join 'lib/coffeescript', "#{name}.js"
     new CompileSources {coffeeSource, jsOut}
-  await Promise.all compileRequests.map (r) -> await r.cachedExecute console
+  Promise.all compileRequests.map (r) -> r.cachedExecute console
 
-build = ->
-  await buildParser()
-  await buildExceptParser()
+build = -> Promise.all [buildParser(), buildExceptParser()]
 
 transpile = (code, options = {}) ->
   options.minify =      process.env.MINIFY    isnt 'false'

build-support/caching.coffee

@@ -123,6 +123,12 @@ class Attestation
     @constructor.objectEquals cached, generated
 
 
+exports.TaskError = class TaskError extends Error
+  printAndExit: (task, console) ->
+    console.error "failed: #{task.print()}"
+    process.exit 1
+
+
 exports.BuildTask = class BuildTask
   identifier: -> throw new TypeError "unimplemented: #{@constructor.name}"
   inputSources: -> throw new TypeError "unimplemented: #{@constructor.name}"
@@ -157,7 +163,12 @@ exports.BuildTask = class BuildTask
     console.info "task '#{@identifier()}' was not cached; executing"
     console.log @print()
     startTask = performance.now()
-    await @execute()
+
+    await @execute(console).catch (e) => switch
+      when e instanceof TaskError
+        e.printAndExit @, console
+      else Promise.reject e
+
     endTask = performance.now()
     console.info "task '#{@identifier()}' complete (#{endTask - startTask} ms)"
     console.debug "caching task '#{@identifier()}' at '#{@attestationPath()}'"

build-support/compile-sources.coffee

@@ -1,7 +1,8 @@
-{ BuildTask, ChecksumFiles } = require './caching'
-{ spawnNodeProcess }         = require './subprocess'
-{ createHash }               = require 'crypto'
-path                         = require 'path'
+{ BuildTask, ChecksumFiles }  = require './caching'
+{ invokeProcess, captureErr } = require './subprocess'
+{ createHash }                = require 'crypto'
+path                          = require 'path'
+process                       = require 'process'
 
 
 exports.CompileSources = class CompileSources extends BuildTask
@@ -22,15 +23,17 @@ exports.CompileSources = class CompileSources extends BuildTask
     {srcName, outName, digest} = @extractNameKeys()
     "compile-sources-#{srcName}-#{outName}-#{digest}"
 
-  constructor: ({@coffeeSource, @jsOut}) ->
+  constructor: ({@coffeeSource, @jsOut, @coffeeBin = 'bin/coffee'}) ->
     super()
     unless @coffeeSource.match /\.(lit)?coffee$/
       throw new TypeError "coffee source file must end in .coffee or .litcoffee (was: '#{@coffeeSource}')"
     unless @jsOut.match /\.js$/
       throw new TypeError "js output file must end in .js (was: '#{@jsOut}')"
 
-  inputSources: -> new ChecksumFiles [@coffeeSource]
+  inputSources: -> new ChecksumFiles [@coffeeSource, @coffeeBin]
   outputSources: -> new ChecksumFiles [@jsOut]
   print: -> "coffee compile: #{@coffeeSource} -> #{@jsOut}"
 
-  execute: -> await spawnNodeProcess ['bin/coffee', '-c', '-o', @jsOut, @coffeeSource]
+  execute: (console) ->
+    proc = await invokeProcess process.execPath, [@coffeeBin, '-c', '-o', @jsOut, @coffeeSource]
+    await captureErr proc

build-support/parser.coffee

@@ -8,10 +8,12 @@ exports.JisonParser = class JisonParser extends BuildTask
     @grammarPath = 'lib/coffeescript/grammar.js',
     @parserPath = 'lib/coffeescript/parser.js',
     @jisonScript = 'build-support/jison-script.coffee',
+    @pkgLock = 'node_modules/.package-lock.json',
+    @coffeeBin = 'bin/coffee',
   } = {}) -> super()
 
-  inputSources: -> new ChecksumFiles [@grammarPath, @jisonScript]
+  inputSources: -> new ChecksumFiles [@grammarPath, @jisonScript, @pkgLock, @coffeeBin]
   outputSources: -> new ChecksumFiles [@parserPath]
   print: -> "jison generate: #{@grammarPath} -> #{@parserPath}"
 
-  execute: -> await spawnNodeProcess ['bin/coffee', @jisonScript, @grammarPath, @parserPath]
+  execute: -> await spawnNodeProcess [@coffeeBin, @jisonScript, @grammarPath, @parserPath]

build-support/subprocess.coffee

@@ -1,14 +1,19 @@
-{ spawn } = require 'child_process'
-process   = require 'process'
+{ spawn }     = require 'child_process'
+process       = require 'process'
+{ TaskError } = require './caching'
 
 
-exports.SubprocessError = class SubprocessError extends Error
+exports.SubprocessError = class SubprocessError extends TaskError
   constructor: (@child, ...rest) -> super ...rest
   exe: -> @child.spawnfile
   args: -> @child.spawnargs
 
+  printAndExit: (task, console) ->
+    console.error "process '#{@exe()}' [#{@args().join ', '}] failed: #{@message}"
+    super task, console
+
 exports.SpawnFailed = class SpawnFailed extends SubprocessError
-  constructor: (child, cause) -> super child, 'process spawn failed', {cause}
+  constructor: (child, cause) -> super child, 'process spawn failed: #{cause.message}', {cause}
 
 exports.ProcessCompletedError = class ProcessCompletedError extends SubprocessError
 exports.SignalReceived = class SignalReceived extends ProcessCompletedError
@@ -22,6 +27,14 @@ exports.NonZeroExit = class NonZeroExit extends ProcessCompletedError
 exports.Aborted = class Aborted extends ProcessCompletedError
   constructor: (child, cause) -> super child, 'process aborted', {cause}
 
+exports.OutputCapturedError = class OutputCapturedError extends ProcessCompletedError
+  constructor: (@capturedOutput, cause) ->
+    super cause.child, cause.message, {cause}
+
+  printAndExit: (task, console) ->
+    process.stderr.write @capturedOutput
+    super task, console
+
 
 # Async process spawning.
 exports.invokeProcess = invokeProcess = (...spawnArgs) -> new Promise (resolve, reject) ->
@@ -66,3 +79,15 @@ exports.spawnNodeProcess = (args, {output = 'stderr'} = {}) ->
   capture proc
 
   await collectNone proc
+
+
+exports.captureErr = captureErr = (proc) ->
+  getErrChunks = do (proc) ->
+    out = ''
+    for await chunk from proc.stderr.setEncoding 'utf8'
+      out += chunk
+    out
+  collectNone(proc).catch (e) -> switch
+    when e instanceof SubprocessError
+      getErrChunks.then (errChunks) -> Promise.reject new OutputCapturedError errChunks, e
+    else Promise.reject e