From 5ca901cfa6c78365cf829d1c6b4e9efa75a0781b Mon Sep 17 00:00:00 2001
From: Gabriel Scherer <gabriel.scherer@gmail.com>
Date: May 03 2014 21:21:58 +0000
Subject: ocamlbuild: only show backtrace in verbose mode


Building foo.cmo in an empty directory (so with in particular no
foo.ml) currently returns the following output:

> Solver failed:
>   Ocamlbuild cannot find or build foo.ml.  A file with such a name
>   would usually be a source file.  I suspect you have given a wrong
>   target name to Ocamlbuild.
> Backtrace:
>   - Failed to build the target foo.cmo
>       - Building foo.cmo:
>           - Failed to build all of these:
>               - Building foo.ml:
>                   - Failed to build all of these:
>                       - Building foo.mly
>                       - Building foo.mll
>               - Building foo.mli:
>                   - Building foo.mly
>               - Building foo.mlpack
>               - Building foo.mli:
>                   - Building foo.mly
> Compilation unsuccessful after building 0 targets (0 cached) in 00:00:00.

While the "Solver failed" part is nice and reasonably easy to
understand, users report that the "Backtrace" part is confusing
(it talks about files they don't know about) -- and it can be so large
that the explanation above is completely hidden.

This patch disables backtrace-printing by default; it is now only
shown when some "-verbose N" (N starting at 1) argument is passed.

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@14732 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02

---

diff --git a/ocamlbuild/main.ml b/ocamlbuild/main.ml
index 5f86f79..f3aef9e 100644
--- a/ocamlbuild/main.ml
+++ b/ocamlbuild/main.ml
@@ -282,8 +282,10 @@ let main () =
           Log.finish ~how:`Quiet ();
           Pervasives.exit rc
       | Solver.Failed backtrace ->
-          Log.raw_dprintf (-1) "@[<v0>@[<2>Solver failed:@ %a@]@\n@[<v2>Backtrace:%a@]@]@."
-            Report.print_backtrace_analyze backtrace Report.print_backtrace backtrace;
+          Log.raw_dprintf (-1) "@[<v0>@[<2>Solver failed:@ %a@]@."
+            Report.print_backtrace_analyze backtrace;
+          Log.raw_dprintf 1 "@[<v2>Backtrace:%a@]@]@."
+            Report.print_backtrace backtrace;
           exit rc_solver_failed
       | Failure s ->
           Log.eprintf "Failure:@ %s." s;