[builtin/shvar] Clear the PATH cache when modifying PATH

So that shvar PATH='' { ... } can be used to make all binaries
invisible.

This mechanism is for config files #951.

[doc] Plan out more of Oil as well.  QTT builtins.

core/shell.py

@@ -183,11 +183,11 @@ def AddProcess(
   b[builtin_i.forkwait] = builtin_process.ForkWait(shell_ex)
 
 
-def AddOil(b, mem, cmd_ev, errfmt, procs, arena):
-  # type: (Dict[int, vm._Builtin], state.Mem, cmd_eval.CommandEvaluator, ui.ErrorFormatter, Dict[str, Proc], alloc.Arena) -> None
+def AddOil(b, mem, search_path, cmd_ev, errfmt, procs, arena):
+  # type: (Dict[int, vm._Builtin], state.Mem, state.SearchPath, cmd_eval.CommandEvaluator, ui.ErrorFormatter, Dict[str, Proc], alloc.Arena) -> None
   b[builtin_i.append] = builtin_oil.Append(mem, errfmt)
 
-  b[builtin_i.shvar] = builtin_pure.Shvar(mem, cmd_ev)
+  b[builtin_i.shvar] = builtin_pure.Shvar(mem, search_path, cmd_ev)
   b[builtin_i.push_registers] = builtin_pure.PushRegisters(mem, cmd_ev)
 
   b[builtin_i.write] = builtin_oil.Write(mem, errfmt)
@@ -452,7 +452,7 @@ def Main(lang, arg_r, environ, login_shell, loader, line_input):
   cmd_ev = cmd_eval.CommandEvaluator(mem, exec_opts, errfmt, procs,
                                      assign_b, arena, cmd_deps)
 
-  AddOil(builtins, mem, cmd_ev, errfmt, procs, arena)
+  AddOil(builtins, mem, search_path, cmd_ev, errfmt, procs, arena)
 
   # PromptEvaluator rendering is needed in non-interactive shells for @P.
   prompt_ev = prompt.Evaluator(lang, version_str, parse_ctx, mem)

doc/oil-help-topics.md

@@ -111,6 +111,7 @@ feature is **unimplemented**.
   [Shell State]   oil-cd   oil-shopt     compatible, and takes a block
                   shvar                  Temporary modify global settings
                   push-registers         Save registers like $?, PIPESTATUS
+                  X push-procs           Limit the procs visible
   [Modules]       runproc                Run a proc; use as main entry point
                   module                 guard against duplicate 'source'
                   use                    change first word lookup
@@ -120,7 +121,13 @@ feature is **unimplemented**.
                   X fopen                Open multiple streams, takes a block
                   X log   X die          common functions (polyfill)
   [Data Formats]  json   X qtt
-X [Testing]       X describe             Test harness
+X [QTT]           where                  pick rows; dplyr filter()
+                  select                 pick columns
+                  group-by               add a column with a group ID [ext]
+                  sort-by                sort by columns; dplyr arrange() [ext]
+                  summarize              count, sum, histogram, etc. [ext]
+X [Testing]       describe               Test harness
+                  assert                 takes an expression
 X [External Lang] BEGIN   END   when (awk)
                   rule (make)   each (xargs)   fs (find)
 ```
@@ -233,7 +240,7 @@ X [String]        find()   sub()   join()
   [Arrays]        X index()   append()   extend()
   [Assoc Arrays]  @keys()   @values()
   [Introspection] shvar_get()
-X [Config Gen]    parse_file()   eval_to_dict()   block_to_str()   
+X [Config Gen]    parse_config()   eval_to_dict()   block_to_str()   
 X [Better Syntax] lstrip()   rstrip()   lstripglob()   rstripglob()
                   upper()   lower()
                   strftime()

osh/builtin_pure.py

@@ -619,9 +619,10 @@ def Run(self, cmd_val):
 
 
 class Shvar(vm._Builtin):
-  def __init__(self, mem, cmd_ev):
-    # type: (state.Mem, CommandEvaluator) -> None
+  def __init__(self, mem, search_path, cmd_ev):
+    # type: (state.Mem, SearchPath, CommandEvaluator) -> None
     self.mem = mem
+    self.search_path = search_path  # to clear PATH
     self.cmd_ev = cmd_ev  # To run blocks
 
   def Run(self, cmd_val):
@@ -645,6 +646,10 @@ def Run(self, cmd_val):
         raise error.Usage('Expected name=value', span_id=arg_spids[i])
       pairs.append((name, s))
 
+      # Important fix: shvar PATH='' { } must make all binaries invisible
+      if name == 'PATH': 
+        self.search_path.ClearCache()
+
     with state.ctx_Shvar(self.mem, pairs):
       unused = self.cmd_ev.EvalBlock(block)
 

spec/oil-config.test.sh

@@ -135,16 +135,14 @@ shopt --set parse_brace
 
 echo hi > file
 
-# TODO: Fix this cache
-# This CACHES the lookup.  Bad.
-# Do we turn this off in Oil?
-cp -v file /tmp
+# Note: this CACHES the lookup, so shvar has to clear cache when modifying it
+cp -v file /tmp >&2
 echo status=$?
 
 # TODO: implement this, and call it whenever shvar mutates PATH?
 # what about when PATH is mutated?   No leave it out for now.
 
-hash -d  # clear the cache
+# hash -r  # clear the cache, no longer necessary
 
 shvar PATH='' {
   cp -v file /tmp
@@ -160,6 +158,7 @@ cp -v file /tmp >&2
 echo status=$?
 
 ## STDOUT:
+status=0
 status=127
 status=127
 status=0

test/spec.sh

@@ -894,7 +894,7 @@ oil-blocks() {
 }
 
 oil-config() {
-  sh-spec spec/oil-config.test.sh --osh-failures-allowed 3 \
+  sh-spec spec/oil-config.test.sh --osh-failures-allowed 2 \
     $OSH_LIST "$@"
 }