better error position display

include/mruby.h

@@ -55,7 +55,8 @@ typedef struct {
   int stackidx;
   int nregs;
   int argc;
-  mrb_code *pc;
+  mrb_code *pc;                 /* return address */
+  mrb_code *err;                /* error position */
   int acc;
   struct RClass *target_class;
   int ridx;

src/backtrace.c

@@ -77,18 +77,21 @@ mrb_output_backtrace(mrb_state *mrb, struct RObject *exc, output_stream_func fun
     if (MRB_PROC_CFUNC_P(ci->proc)) {
       continue;
     }
-    if(!MRB_PROC_CFUNC_P(ci->proc)) {
+    else {
       mrb_irep *irep = ci->proc->body.irep;
       mrb_code *pc;
 
-      if (i+1 <= ciidx) {
-        pc = mrb->c->cibase[i+1].pc;
+      if (mrb->c->cibase[i].err) {
+        pc = mrb->c->cibase[i].err;
+      }
+      else if (i+1 <= ciidx) {
+        pc = mrb->c->cibase[i+1].pc - 1;
       }
       else {
         pc = (mrb_code*)mrb_cptr(mrb_obj_iv_get(mrb, exc, mrb_intern2(mrb, "lastpc", 6)));
       }
-      filename = mrb_debug_get_filename(irep, pc - irep->iseq - 1);
-      line = mrb_debug_get_line(irep, pc - irep->iseq - 1);
+      filename = mrb_debug_get_filename(irep, pc - irep->iseq);
+      line = mrb_debug_get_line(irep, pc - irep->iseq);
     }
     if (line == -1) continue;
     if (ci->target_class == ci->proc->target_class)

src/error.c

@@ -194,14 +194,16 @@ exc_debug_info(mrb_state *mrb, struct RObject *exc)
   mrb_code *pc = ci->pc;
 
   mrb_obj_iv_set(mrb, exc, mrb_intern2(mrb, "ciidx", 5), mrb_fixnum_value(ci - mrb->c->cibase));
-  ci--;
   while (ci >= mrb->c->cibase) {
-    if (ci->proc && !MRB_PROC_CFUNC_P(ci->proc)) {
+    mrb_code *err = ci->err;
+
+    if (!err && pc) err = pc - 1;
+    if (err && ci->proc && !MRB_PROC_CFUNC_P(ci->proc)) {
       mrb_irep *irep = ci->proc->body.irep;
 
-      int32_t const line = mrb_debug_get_line(irep, pc - irep->iseq - 1);
-      char const* file = mrb_debug_get_filename(irep, pc - irep->iseq - 1);
-      if(line != -1 && file) {
+      int32_t const line = mrb_debug_get_line(irep, err - irep->iseq);
+      char const* file = mrb_debug_get_filename(irep, err - irep->iseq);
+      if (line != -1 && file) {
         mrb_obj_iv_set(mrb, exc, mrb_intern2(mrb, "file", 4), mrb_str_new_cstr(mrb, file));
         mrb_obj_iv_set(mrb, exc, mrb_intern2(mrb, "line", 4), mrb_fixnum_value(line));
         return;

src/vm.c

@@ -226,6 +226,8 @@ cipush(mrb_state *mrb)
   ci->eidx = eidx;
   ci->ridx = ridx;
   ci->env = 0;
+  ci->pc = 0;
+
   return ci;
 }
 
@@ -509,8 +511,9 @@ argnum_error(mrb_state *mrb, int num)
   mrb->exc = mrb_obj_ptr(exc);
 }
 
+#define ERR_PC_HOOK(mrb, pc) mrb->c->ci->err = pc;
 #ifdef ENABLE_DEBUG
-#define CODE_FETCH_HOOK(mrb, irep, pc, regs) if ((mrb)->code_fetch_hook) (mrb)->code_fetch_hook((mrb), (irep), (pc), (regs)); 
+#define CODE_FETCH_HOOK(mrb, irep, pc, regs) if ((mrb)->code_fetch_hook) (mrb)->code_fetch_hook((mrb), (irep), (pc), (regs));
 #else
 #define CODE_FETCH_HOOK(mrb, irep, pc, regs)
 #endif
@@ -593,6 +596,7 @@ mrb_run(mrb_state *mrb, struct RProc *proc, mrb_value self)
     stack_init(mrb);
   }
   stack_extend(mrb, irep->nregs, irep->nregs);
+  mrb->c->ci->err = pc;
   mrb->c->ci->proc = proc;
   mrb->c->ci->nregs = irep->nregs + 1;
   regs = mrb->c->stack;
@@ -684,6 +688,7 @@ mrb_run(mrb_state *mrb, struct RProc *proc, mrb_value self)
 
     CASE(OP_GETCV) {
       /* A B    R(A) := ivget(Sym(B)) */
+      ERR_PC_HOOK(mrb, pc);
       regs[GETARG_A(i)] = mrb_vm_cv_get(mrb, syms[GETARG_Bx(i)]);
       NEXT;
     }
@@ -696,6 +701,7 @@ mrb_run(mrb_state *mrb, struct RProc *proc, mrb_value self)
 
     CASE(OP_GETCONST) {
       /* A B    R(A) := constget(Sym(B)) */
+      ERR_PC_HOOK(mrb, pc);
       regs[GETARG_A(i)] = mrb_vm_const_get(mrb, syms[GETARG_Bx(i)]);
       NEXT;
     }
@@ -710,6 +716,7 @@ mrb_run(mrb_state *mrb, struct RProc *proc, mrb_value self)
       /* A B C  R(A) := R(C)::Sym(B) */
       int a = GETARG_A(i);
 
+      ERR_PC_HOOK(mrb, pc);
       regs[a] = mrb_const_get(mrb, regs[a], syms[GETARG_Bx(i)]);
       NEXT;
     }