feature/igc fda6f96c98c: Make IGC_CHECK_RES error messages more specific

[Stefan Kangas]

branch: feature/igc
commit fda6f96c98ca41fde067f658749f96fb695667c5
Author: Stefan Kangas <stefankangas@gmail.com>
Commit: Stefan Kangas <stefankangas@gmail.com>

    Make IGC_CHECK_RES error messages more specific
    
    * src/igc.c (result_string): New function returning strings describing
    errors.  The descriptions are based on the "Error handling" chapter in
    the MPS Reference, and are adapted to be somewhat user-facing.
    (check_res): Use it.
---
 src/igc.c | 31 +++++++++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

diff --git a/src/igc.c b/src/igc.c
index 158684ca0c1..257e7dc53f7 100644
--- a/src/igc.c
+++ b/src/igc.c
@@ -252,13 +252,40 @@ enum igc_state
 static enum igc_state igc_state = IGC_STATE_INITIAL;
 static void set_state (enum igc_state state);
 
+static const char *
+result_string (mps_res_t res)
+{
+  switch (res)
+    {
+    case MPS_RES_OK:
+      return "operation succeeded";
+    case MPS_RES_FAIL:
+      return "operation failed";
+    case MPS_RES_IO:
+      return "an I/O error occurred in the telemetry system";
+    case MPS_RES_LIMIT:
+      return "an internal limitation was exceeded";
+    case MPS_RES_MEMORY:
+      return "out of memory";
+    case MPS_RES_RESOURCE:
+      return "a needed resource could not be obtained";
+    case MPS_RES_UNIMPL:
+      return "operation is not implemented (this is probably a bug)";
+    case MPS_RES_COMMIT_LIMIT:
+      return "the arena's commit limit would be exceeded";
+    case MPS_RES_PARAM:
+      return "an invalid parameter was passed (this is probably a bug)";
+    }
+  return "unknown error";
+}
+
 static void
 check_res (const char *file, unsigned line, mps_res_t res)
 {
   if (res != MPS_RES_OK)
     {
-      fprintf (stderr, "\r\n%s:%u: Emacs fatal error: MPS error code %d\r\n",
-              file, line, res);
+      fprintf (stderr, "\r\n%s:%u: Emacs fatal error: MPS error %d: %s\r\n",
+              file, line, res, result_string (res));
       set_state (IGC_STATE_DEAD);
     }
 }