Propagate tracebacks from code objects that raise. Expose some fields to Python.

runtime/block.go

@@ -48,18 +48,6 @@ func (b *Block) execInternal(f *Frame, sendValue *Object) (*Object, *BaseExcepti
 			return ret, nil
 		}
 		if len(f.checkpoints) == 0 {
-			if f.back != nil {
-				e, tb := f.ExcInfo()
-				if e != raised {
-					// This is likely due to a programming
-					// error. Prefer raised and start
-					// propagating from here.
-					tb = newTraceback(f, nil)
-				} else {
-					tb = newTraceback(f.back, tb)
-				}
-				f.RestoreExc(raised, tb)
-			}
 			return nil, raised
 		}
 		f.state = f.PopCheckpoint()

runtime/code.go

@@ -17,8 +17,8 @@ const (
 
 type Code struct {
 	Object
-	name     string
-	filename string
+	name     string `attr:"co_name"`
+	filename string `attr:"co_filename"`
 	// argc is the number of positional arguments.
 	argc int `attr:"co_argcount"`
 	// minArgc is the number of positional non-keyword arguments (i.e. the
@@ -112,9 +112,20 @@ func (c *Code) Eval(f *Frame, globals *Dict, args Args, kwargs KWArgs) (*Object,
 			bodyArgs[i] = arg.Def
 		}
 	}
+	oldExc, oldTraceback := f.ExcInfo()
 	next := newFrame(f)
+	next.code = c
 	next.globals = globals
 	ret, raised := c.fn(next, bodyArgs)
 	f.FreeArgs(bodyArgs)
+	if raised == nil {
+		// Restore exc_info to what it was when we left the previous
+		// frame.
+		f.RestoreExc(oldExc, oldTraceback)
+	} else {
+		_, tb := f.ExcInfo()
+		tb = newTraceback(f, tb)
+		f.RestoreExc(raised, tb)
+	}
 	return ret, raised
 }

runtime/frame.go

@@ -38,6 +38,7 @@ type Frame struct {
 	state       RunState
 	globals     *Dict `attr:"f_globals"`
 	lineno      int   `attr:"f_lineno"`
+	code        *Code `attr:"f_code"`
 }
 
 // newFrame creates a new Frame whose parent frame is back.

runtime/traceback.go

@@ -22,7 +22,7 @@ import (
 type Traceback struct {
 	Object
 	frame  *Frame     `attr:"tb_frame"`
-	next   *Traceback
+	next   *Traceback `attr:"tb_next"`
 	lineno int        `attr:"tb_lineno"`
 }