remove generating logs for slow slice types

Signed-off-by: Andres Taylor <[email protected]>

go/tools/astfmtgen/main.go

@@ -247,7 +247,7 @@ func (r *Rewriter) rewriteAstPrintf(cursor *astutil.Cursor, expr *ast.CallExpr)
 				Args: []ast.Expr{&ast.BasicLit{Value: `"%d"`, Kind: gotoken.STRING}, expr.Args[2+fieldnum]},
 			}
 			cursor.InsertBefore(r.rewriteLiteral(callexpr.X, "WriteString", call))
-		case 'n': // new directive for slices of AST nodes checked at code generation time
+		case 'n': // directive for slices of AST nodes checked at code generation time
 			inputExpr := expr.Args[2+fieldnum]
 			inputType := r.pkg.TypesInfo.Types[inputExpr].Type
 			sliceType, ok := inputType.(*types.Slice)
@@ -266,31 +266,7 @@ func (r *Rewriter) rewriteAstPrintf(cursor *astutil.Cursor, expr *ast.CallExpr)
 				cursor.InsertBefore(&ast.ExprStmt{X: call})
 				break
 			}
-			log.Printf("slow path for `n` directive with type %T", types.TypeString(inputType, noQualifier))
-			// Slow path: slice elements do not implement Expr
-			cursor.InsertBefore(&ast.ExprStmt{
-				X: &ast.CallExpr{
-					Fun: &ast.SelectorExpr{
-						X:   &ast.Ident{Name: "log"},
-						Sel: &ast.Ident{Name: "Printf"},
-					},
-					Args: []ast.Expr{
-						&ast.BasicLit{
-							Kind:  gotoken.STRING,
-							Value: strconv.Quote("slow path for %n with type %T"),
-						},
-						inputExpr,
-					},
-				},
-			})
-			call := &ast.CallExpr{
-				Fun: &ast.SelectorExpr{
-					X:   callexpr.X,
-					Sel: &ast.Ident{Name: "formatNodes"},
-				},
-				Args: []ast.Expr{inputExpr},
-			}
-			cursor.InsertBefore(&ast.ExprStmt{X: call})
+			panic("slow path for `n` directive for slice of type other than Expr")
 		default:
 			panic(fmt.Sprintf("unsupported escape %q", token))
 		}