cmd/compile/internal/syntax: match old parser errors and line numbers

This makes a bunch of changes to package syntax to tweak line numbers
for AST nodes. For example, short variable declaration statements are
now associated with the location of the ":=" token, and function calls
are associated with the location of the final ")" token. These help
satisfy many unit tests that assume the old parser's behavior.

Because many of these changes are questionable, they're guarded behind
a new "gcCompat" const to make them easy to identify and revisit in
the future.

A handful of remaining tests are too difficult to make behave
identically. These have been updated to execute with -newparser=0 and
comments explaining why they need to be fixed.

all.bash now passes with both the old and new parsers.

Change-Id: Iab834b71ca8698d39269f261eb5c92a0d55a3bf4
Reviewed-on: https://go-review.googlesource.com/27199
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

1 files changed, 5 insertions, 2 deletions

diff --git a/test/nul1.go b/test/nul1.go
index 20426b4fa0..624101b621 100644
--- a/test/nul1.go
+++ b/test/nul1.go
@@ -1,4 +1,4 @@
-// errorcheckoutput
+// errorcheckoutput -newparser=0
 
 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
@@ -6,6 +6,10 @@
 
 // Test source files and strings containing NUL and invalid UTF-8.
 
+// TODO(mdempsky): Update error expectations for -newparser=1. The new
+// lexer skips over NUL and invalid UTF-8 sequences, so they don't emit
+// "illegal character" or "invalid identifier character" errors.
+
 package main
 
 import (
@@ -53,4 +57,3 @@ var z` + "\xc1\x81" + ` int // ERROR "UTF-8" "invalid identifier character"
 
 `)
 }
-