Fixes handling C compilation errors

lukstafi · lukstafi · commit 7661321b1ff5 · 2024-09-11T15:00:16.000+02:00
diff --git a/CHANGES.md b/CHANGES.md
@@ -17,6 +17,7 @@
   - By default do not log from tests.
   - `debug_log_from_routines` should only happen when `log_level > 1`.
 - Bugs in `Multicore_backend`: `await` was not checking queue emptiness, `worker`'s `Condition.broadcast` was non-atomically guarded (doesn't need to be), possible deadloop due to the lockfree queue -- now replaced with `saturn_lockfree`.
+- Reduced busy-waiting inside `c_compile_and_load`, propagating compilation errors now instead of infinite loop on error.
 
 ## [0.4.0] -- 2024-09-04
 
diff --git a/arrayjit/lib/cc_backend.ml b/arrayjit/lib/cc_backend.ml
@@ -108,12 +108,17 @@ let c_compile_and_load ~f_name =
     Printf.sprintf "%s %s -O%d -o %s --shared >> %s 2>&1" (compiler_command ()) f_name
       (optimization_level ()) libname log_fname
   in
-  let _rc = Stdlib.Sys.command cmdline in
-  (* FIXME: don't busy wait *)
-  (* FIXME: detect and propagate compile errors, log compile warnings *)
-  while not @@ (Stdlib.Sys.file_exists libname && Stdlib.Sys.file_exists log_fname) do
-    ()
+  let rc = Stdlib.Sys.command cmdline in
+  while rc = 0 && (not @@ (Stdlib.Sys.file_exists libname && Stdlib.Sys.file_exists log_fname)) do
+    Unix.sleepf 0.001
   done;
+  (if rc <> 0 then
+     let errors =
+       "Cc_backend.c_compile_and_load: compilation failed with errors:\n"
+       ^ Stdio.In_channel.read_all log_fname
+     in
+     Stdio.prerr_endline errors;
+     invalid_arg errors);
   (* Note: RTLD_DEEPBIND not available on MacOS. *)
   let result = { lib = Dl.dlopen ~filename:libname ~flags:[ RTLD_NOW ]; libname } in
   Stdlib.Gc.finalise (fun lib -> Dl.dlclose ~handle:lib.lib) result;
