single argument panic

note that sortmain.go has been run through hg gofmt;
only the formatting of the day initializers changed.
i'm happy to revert that formatting if you'd prefer.

stop on error in doc/progs/run

R=r
CC=golang-dev
http://codereview.appspot.com/850041

3 files changed, 4 insertions, 5 deletions

diff --git a/src/pkg/go/ast/walk.go b/src/pkg/go/ast/walk.go
index 2137ddaa4..6c9837a01 100644
--- a/src/pkg/go/ast/walk.go
+++ b/src/pkg/go/ast/walk.go
@@ -316,7 +316,7 @@ func Walk(v Visitor, node interface{}) {
 
 	default:
 		fmt.Printf("ast.Walk: unexpected type %T", n)
-		panic()
+		panic("ast.Walk")
 	}
 
 	v.Visit(nil)
diff --git a/src/pkg/go/parser/parser.go b/src/pkg/go/parser/parser.go
index 2002d3818..6831a53de 100644
--- a/src/pkg/go/parser/parser.go
+++ b/src/pkg/go/parser/parser.go
@@ -1738,8 +1738,7 @@ func (p *parser) parseForStmt() ast.Stmt {
 		return &ast.ForStmt{pos, s1, p.makeExpr(s2), s3, body}
 	}
 
-	panic() // unreachable
-	return nil
+	panic("unreachable")
 }
 
 
diff --git a/src/pkg/go/printer/printer.go b/src/pkg/go/printer/printer.go
index 5a12c6edb..2316a459b 100644
--- a/src/pkg/go/printer/printer.go
+++ b/src/pkg/go/printer/printer.go
@@ -107,7 +107,7 @@ func (p *printer) internalError(msg ...interface{}) {
 	if debug {
 		fmt.Print(p.pos.String() + ": ")
 		fmt.Println(msg)
-		panic()
+		panic("go/printer")
 	}
 }
 
@@ -791,7 +791,7 @@ func (p *printer) print(args ...interface{}) {
 			}
 		default:
 			fmt.Fprintf(os.Stderr, "print: unsupported argument type %T\n", f)
-			panic()
+			panic("go/printer type")
 		}
 		p.pos = next