Add always-show-command-lines-on-error option

And hide the full commands when:
* The error starts with "File "
* we aren't inside CI

Signed-off-by: Rudi Grinberg <rudi.grinberg@gmail.com>

bin/common.ml

@@ -40,6 +40,7 @@ type t =
   (* For build & runtest only *)
   ; watch : bool
   ; stats_trace_file : string option
+  ; always_show_command_lines_on_error : bool
   }
 
 let prefix_target common s = common.target_prefix ^ s
@@ -67,6 +68,8 @@ let set_common_other c ~targets =
       ; c.orig_args
       ; targets
       ];
+  Clflags.always_show_command_lines_on_error :=
+    c.always_show_command_lines_on_error;
   Option.iter ~f:Dune.Stats.enable c.stats_trace_file
 
 let set_common c ~targets =
@@ -153,6 +156,11 @@ let term =
     | false , Some x -> `Ok (Some x)
     | true  , None   -> `Ok (Some Config.Display.Verbose)
     | true  , Some _ -> incompatible "--display" "--verbose"
+  and+ always_show_command_lines_on_error =
+    let doc = "Always show full command on error" in
+    Arg.(value
+         & flag
+         & info ["always-show-command-lines-on-error"] ~docs ~doc)
   and+ no_buffer =
     Arg.(value
          & flag
@@ -416,6 +424,7 @@ let term =
   ; default_target
   ; watch
   ; stats_trace_file
+  ; always_show_command_lines_on_error
   }
 
 let term =

bin/common.mli

@@ -23,6 +23,7 @@ type t =
   (* For build & runtest only *)
   ; watch : bool
   ; stats_trace_file : string option
+  ; always_show_command_lines_on_error : bool
   }
 
 val prefix_target : t -> string -> string

src/clflags.ml

@@ -9,3 +9,4 @@ let force = ref false
 let watch = ref false
 let no_print_directory = ref false
 let store_orig_src_dir = ref false
+let always_show_command_lines_on_error = ref false

src/clflags.mli

@@ -32,3 +32,6 @@ val no_print_directory : bool ref
 
 (** Store original source directory in dune-package metadata *)
 val store_orig_src_dir : bool ref
+
+(** Always show full command on error *)
+val always_show_command_lines_on_error : bool ref

src/config.ml

@@ -26,6 +26,9 @@ let inside_emacs = Option.is_some (Env.get Env.initial "INSIDE_EMACS")
 let inside_dune  = Option.is_some (Env.get Env.initial "INSIDE_DUNE")
 let inside_ci = Option.is_some (Env.get Env.initial "CI")
 
+let show_full_command_on_error () =
+  inside_ci || !Clflags.always_show_command_lines_on_error
+
 let default_build_profile =
   match Wp.t with
   | Dune     -> "dev"

src/config.mli

@@ -28,6 +28,8 @@ val inside_dune : bool
     supported by travis, gitlab.*)
 val inside_ci : bool
 
+val show_full_command_on_error : unit -> bool
+
 val default_build_profile : string
 
 (** Dune configuration *)

src/process.ml

@@ -250,7 +250,6 @@ let run_internal ?dir ?(stdout_to=Output.stdout) ?(stderr_to=Output.stderr)
       ~env ~purpose fail_mode prog args =
   let* scheduler = Scheduler.wait_for_available_job () in
   let display = Console.display () in
-  let show_command_on_error = not !Clflags.watch in
   let dir =
     match dir with
     | Some p ->
@@ -354,13 +353,18 @@ let run_internal ?dir ?(stdout_to=Output.stdout) ?(stderr_to=Output.stderr)
     end;
     n
   | WEXITED n ->
+    let show_command =
+      let error_starts_with_file = String.is_prefix output ~prefix:"File " in
+      Config.show_full_command_on_error ()
+      || (not error_starts_with_file)
+    in
     if display = Verbose then
       die "\n@{<kwd>Command@} [@{<id>%d@}] exited with code %d:\n\
            @{<prompt>$@} %s\n%s"
         id n
         (Colors.strip_colors_for_stderr command_line)
         (Colors.strip_colors_for_stderr output)
-    else if show_command_on_error then
+    else if show_command then
       die "@{<error>%12s@} %a @{<error>(exit %d)@}\n\
            @{<details>%s@}\n\
            %s"