feat(run): run blocks for commands the build does not produce

bin/meowc.ml

@@ -8,7 +8,7 @@ let usage =
       "";
       Style.bold "  usage";
       "    meowc [build] [target...]     build everything, or the named targets";
-      "    meowc run <bin> [args...]     build a bin target, then run it";
+      "    meowc run <name> [args...]    run a bin target, or a run block";
       "    meowc test [filter]           build and run test targets";
       "    meowc install                 copy installable outputs under the prefix";
       "    meowc configure               run the checks and write the config header";
@@ -259,24 +259,46 @@ let cmd_build names =
   summarise r (Unix.gettimeofday () -. t0);
   p
 
+let runnable_names p =
+  List.filter_map (fun (t : target) -> if t.kind = Bin then Some t.name else None) p.targets
+  @ List.map (fun (s : script) -> s.sname) p.scripts
+
+let hand_over cmd =
+  flush stdout;
+  try Unix.execvp cmd.(0) cmd
+  with Unix.Unix_error (e, _, _) -> Diag.error "cannot run %s: %s" cmd.(0) (Unix.error_message e)
+
 let cmd_run = function
-  | [] -> Diag.error ~hint:"try: meowc run <bin>" "run needs a target name"
-  | name :: args ->
+  | [] -> Diag.error ~hint:"try: meowc run <bin>" "run needs a name"
+  | name :: args -> (
       let p = configure () in
-      let t = match find p name with
-        | Some ({ kind = Bin; _ } as t) -> t
-        | Some t -> Diag.error "%s is a %s, not a bin" name (kind_name t.kind)
-        | None -> unknown_target p name
+      let build_first names =
+        banner p;
+        with_config_header p;
+        let t0 = Unix.gettimeofday () in
+        let _, r = execute p ~names in
+        summarise r (Unix.gettimeofday () -. t0)
       in
-      banner p;
-      with_config_header p;
-      let t0 = Unix.gettimeofday () in
-      let _, r = execute p ~names:[ name ] in
-      summarise r (Unix.gettimeofday () -. t0);
-      let exe = Build.bin_of p t in
-      if not fl.quiet then Printf.printf "\n  %s\n" (Style.dim exe);
-      flush stdout;
-      Unix.execv exe (Array.of_list (exe :: args))
+      match List.find_opt (fun (s : script) -> s.sname = name) p.scripts with
+      | Some s ->
+          (* no names means everything, the same as a bare meowc build *)
+          build_first s.suses;
+          let cmd = Array.of_list (s.scmd @ args) in
+          if not fl.quiet then Printf.printf "\n  %s\n" (Style.dim (Exec.show cmd));
+          hand_over cmd
+      | None ->
+          let t =
+            match find p name with
+            | Some ({ kind = Bin; _ } as t) -> t
+            | Some t -> Diag.error "%s is a %s, not a bin" name (kind_name t.kind)
+            | None ->
+                Diag.error ~hint:(Suggest.hint name (runnable_names p))
+                  "no bin target or run block named %S" name
+          in
+          build_first [ name ];
+          let exe = Build.bin_of p t in
+          if not fl.quiet then Printf.printf "\n  %s\n" (Style.dim exe);
+          hand_over (Array.of_list (exe :: args)))
 
 let cmd_test filter =
   let p = configure () in
@@ -344,7 +366,18 @@ let cmd_targets () =
         (Style.pad 20 (Style.dim (Style.plural (List.length (all_srcs t)) "source")))
         (Style.dim (if t.uses = [] then "" else "uses " ^ String.concat " " t.uses)))
     p.targets;
-  Printf.printf "\n  %s\n" (Style.dim (Style.plural (List.length p.targets) "target"))
+  List.iter
+    (fun (s : script) ->
+      Printf.printf "  %s%s%s\n"
+        (Style.yellow (Style.pad 9 "run"))
+        (Style.pad 22 s.sname)
+        (Style.dim (if s.suses = [] then "" else "uses " ^ String.concat " " s.suses)))
+    p.scripts;
+  Printf.printf "\n  %s\n"
+    (Style.dim
+       (String.concat ", "
+          (Style.plural (List.length p.targets) "target"
+          :: (if p.scripts = [] then [] else [ Style.plural (List.length p.scripts) "run block" ]))))
 
 let cmd_graph () =
   let p = configure () in

examples/raytracer/build.meow

@@ -113,6 +113,13 @@ bin rtbench {
   use     rtscene
 }
 
+# A canned invocation, for a quick low sample preview. ${builddir} follows the
+# target triple, so this still points at the right binary under --target.
+run preview {
+  use     render
+  command ${builddir}/bin/render --scene rings --width 320 --height 180 --samples 8
+}
+
 test math_test {
   srcs    tests/math_test.c
   include include

lib/parse.ml

@@ -6,7 +6,7 @@ let stmt_keywords =
   [ "project"; "set"; "append"; "option"; "include"; "subdir"; "if"; "check"; "pkg";
     "config_header"; "message" ]
 
-let block_kinds = [ "toolchain"; "lib"; "shared"; "bin"; "test"; "rule"; "install" ]
+let block_kinds = [ "toolchain"; "lib"; "shared"; "bin"; "test"; "rule"; "install"; "run" ]
 let check_kinds = [ "header"; "func"; "symbol"; "sizeof"; "compiles" ]
 
 let peek p = p.toks.(p.pos)

lib/resolve.ml

@@ -7,6 +7,7 @@ let target_fields =
 
 let rule_fields = [ "inputs"; "outputs"; "command"; "description" ]
 let install_fields = [ "files"; "to" ]
+let script_fields = [ "use"; "command" ]
 
 let fields_of (b : block) =
   List.filter_map (function FField f -> Some f | FIf _ -> None) b.items
@@ -156,6 +157,20 @@ let installs_of blocks =
       end)
     blocks
 
+let scripts_of blocks =
+  List.concat_map
+    (fun ((b : block), _) ->
+      if b.kind <> "run" then []
+      else begin
+        check_fields b script_fields;
+        let cmd = texts (get b "command") in
+        if cmd = [] then
+          Diag.error ~span:b.nspan ~hint:"add a line like: command ./tool --flag"
+            "run %s declares no command" b.bname;
+        [ { sname = b.bname; suses = texts (get b "use"); scmd = cmd; sspan = b.nspan } ]
+      end)
+    blocks
+
 let project (env : Eval.env) =
   let blocks = env.blocks in
   let rules = rules_of blocks in
@@ -168,7 +183,8 @@ let project (env : Eval.env) =
   in
   List.iter
     (fun (b : block) ->
-      if not (List.mem b.kind [ "lib"; "shared"; "bin"; "test"; "rule"; "install"; "toolchain" ]) then
+      if not (List.mem b.kind [ "lib"; "shared"; "bin"; "test"; "rule"; "install"; "toolchain"; "run" ])
+      then
         Diag.error ~span:b.kspan "unknown block %S" b.kind)
     (List.map fst blocks);
   let seen = Hashtbl.create 8 in
@@ -186,6 +202,7 @@ let project (env : Eval.env) =
       tc = env.tc;
       targets;
       rules;
+      scripts = scripts_of blocks;
       defines = env.defines;
       config_header = env.config_header;
       installs = installs_of blocks;
@@ -208,6 +225,28 @@ let project (env : Eval.env) =
           | Some _ -> ())
         t.uses)
     targets;
+  let seen_runs = Hashtbl.create 4 in
+  List.iter
+    (fun (s : script) ->
+      (match Hashtbl.find_opt seen_runs s.sname with
+      | Some (prev : script) ->
+          Diag.error ~span:s.sspan ~notes:[ (prev.sspan, "first declared here") ]
+            "run %S is declared twice" s.sname
+      | None -> Hashtbl.add seen_runs s.sname s);
+      (* meowc run takes one name, so a run block and a target cannot share one *)
+      (match find p s.sname with
+      | Some (t : target) ->
+          Diag.error ~span:s.sspan ~notes:[ (t.span, "the target is here") ]
+            "run %S has the same name as a target" s.sname
+      | None -> ());
+      List.iter
+        (fun u ->
+          if find p u = None then
+            Diag.error ~span:s.sspan
+              ~hint:(Suggest.hint u (List.map (fun (x : target) -> x.name) targets))
+              "run %s uses %S, which is not a target" s.sname u)
+        s.suses)
+    p.scripts;
   let rec cyc seen t =
     if List.mem t.name seen then
       Diag.error ~span:t.span "dependency cycle: %s" (String.concat " -> " (List.rev (t.name :: seen)));

lib/types.ml

@@ -46,6 +46,10 @@ type toolchain = {
   builddir : string;
 }
 
+(* A command the project can be asked to run, once whatever it names has been
+   built. Unlike a rule it produces no file, so it is never part of the graph. *)
+type script = { sname : string; suses : string list; scmd : string list; sspan : Span.t }
+
 type install_item = { from : string; dest : string }
 
 type define = { dname : string; dvalue : string option }
@@ -55,6 +59,7 @@ type project = {
   tc : toolchain;
   targets : target list;
   rules : rule list;
+  scripts : script list;
   defines : define list;
   config_header : string option;
   installs : install_item list;