choo: track build failures

apps/choo/bootstrap/kernel.hoon

@@ -114,13 +114,17 @@
       %-  ~(create builder u.cached-hoon.k bc.k pc.k)
       [entry dir]
     :_  k(bc new-bc, pc new-pc)
-    :~  :*  %file
-            %write
-            path=(crip "out.jam")
-            contents=(jam compiled)
-        ==
-        [%exit 0]
-    ==
+    =/  exit-code  ?:(=(compiled *(trap vase)) 1 0)
+    =/  write-effect
+      :*  %file
+          %write
+          path=(crip "out.jam")
+          contents=(jam compiled)
+      ==
+    ?:  =(exit-code 0)
+      ~[write-effect [%exit exit-code]]
+    ~&  >>>  "build failed, skipping write"
+    ~[[%exit exit-code]]
   ==
 --
 ::
@@ -351,6 +355,8 @@
   =/  [=build-cache =parse-cache]  (tail compile)
   ::  +shot calls the kernel gate to tell it the hash of the dependency directory
   :_  [build-cache parse-cache]
+  ::  build failure, just return the bunted trap
+  ?:  =(ker-gen *(trap vase))  ker-gen
   =>  %+  shot  ker-gen
     =>  d=!>(dir-hash)
     |.(d)
@@ -475,7 +481,9 @@
 ::    .nodes: the nodes of the dependency graph
 ::    .bc: the build cache
 ::
-::    returns a trap vase with the compiled hoon file and the updated build cache
+::    returns a trap vase with the compiled hoon file and the updated build
+::    cache. if a build failure is detected, a bunted (trap vase) is returned
+::    instead.
 ++  compile-target
   |=  [pat=path =path-dag nodes=(map path node) bc=build-cache]
   ^-  [(trap vase) build-cache]
@@ -490,13 +498,21 @@
   =/  graph  (build-graph-view nodes)
   =/  next=(map path node)  (update-next nodes graph)
   =|  vaz=(trap vase)
-  |-
+  =|  had-error=_|                                     ::  track build failures
+  |-  ^-  [(trap vase) build-cache]
   ?:  .=(~ next)
-    (compile-node n path-dag bc)
+    =/  [final-vaz=(trap vase) final-bc=build-cache]
+      (compile-node n path-dag bc)
+    ?:  |(had-error =(final-vaz *(trap vase)))
+      [*(trap vase) final-bc]                         ::  propagate error state
+    [final-vaz final-bc]
   =.  bc
     %+  roll  ~(tap by next)
     |=  [[p=path n=node] bc=_bc]
-    +:(compile-node n path-dag bc)
+    =/  [node-vaz=(trap vase) new-bc=build-cache]
+      (compile-node n path-dag bc)
+    =.  had-error  |(had-error =(node-vaz *(trap vase)))
+    new-bc
   =.  graph
     (roll ~(tap by next) |=([[p=path *] g=_graph] (update-graph-view g p)))
   %=  $
@@ -524,7 +540,10 @@
     ~&  >  build-cache-hit+path.n
     [(~(got by bc) dep-hash) bc]
   ~&  >  build-cache-miss+path.n
-  =/  vaz=(trap vase)  (build-node n path-dag bc)
+  ?~  moled=(mole |.((build-node n path-dag bc)))
+    ~&  >>  "build-node: failed to compile {<path.n>}"
+    [*(trap vase) bc]
+  =/  vaz=(trap vase)  u.moled
   [vaz (~(put by bc) dep-hash vaz)]
 ::
 ::  $build-node: build a single node and its dependencies
@@ -537,11 +556,10 @@
 ++  build-node
   |=  [n=node =path-dag bc=build-cache]
   ^-  (trap vase)
+  ~>  %bout
   =;  dep-vaz=(trap vase)
-    ~>  %bout
-    (swet (slew honc dep-vaz) hoon.n)
-  %+  roll
-    deps.n
+    (swet (slat honc dep-vaz) hoon.n)
+  %+  roll  deps.n
   |=  [raut vaz=(trap vase)]
   ~&  >  grabbing-dep+pax
   =/  [dep-hash=@ dep-node=node]
@@ -550,7 +568,7 @@
   =/  dep-vaz=(trap vase)
     ~|  "couldn't find artifact for {<pax>} in build cache"
     (~(got by bc) dep-hash)
-  (slew vaz (label-vase dep-vaz face))
+  (slat vaz (label-vase dep-vaz face))
 ::
 ::  $label-vase: label a (trap vase) with a face
 ::
@@ -695,13 +713,13 @@
   %-  silt
   (turn deps.n |=(raut pax))
 ::
-::  $slew: merge two (trap vase)s
+::  $slat: merge two (trap vase)s
 ::
 ::    .hed: the first (trap vase)
 ::    .tal: the second (trap vase)
 ::
 ::    returns a merged (trap vase)
-++  slew
+++  slat
   |=  [hed=(trap vase) tal=(trap vase)]
   ^-  (trap vase)
   =>  +<