libgo: Add sources for go, cgo, and gofmt commands.

The new commands are not yet built.  That will be done
separately.

Also include a few changes to go/build to support them.

From-SVN: r219272

1 files changed, 93 insertions, 0 deletions

diff --git a/libgo/go/cmd/gofmt/doc.go b/libgo/go/cmd/gofmt/doc.go
new file mode 100644
index 0000000..8f73ef5
--- /dev/null
+++ b/libgo/go/cmd/gofmt/doc.go
@@ -0,0 +1,93 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+Gofmt formats Go programs.
+It uses tabs (width = 8) for indentation and blanks for alignment.
+
+Without an explicit path, it processes the standard input.  Given a file,
+it operates on that file; given a directory, it operates on all .go files in
+that directory, recursively.  (Files starting with a period are ignored.)
+By default, gofmt prints the reformatted sources to standard output.
+
+Usage:
+	gofmt [flags] [path ...]
+
+The flags are:
+	-d
+		Do not print reformatted sources to standard output.
+		If a file's formatting is different than gofmt's, print diffs
+		to standard output.
+	-e
+		Print all (including spurious) errors.
+	-l
+		Do not print reformatted sources to standard output.
+		If a file's formatting is different from gofmt's, print its name
+		to standard output.
+	-r rule
+		Apply the rewrite rule to the source before reformatting.
+	-s
+		Try to simplify code (after applying the rewrite rule, if any).
+	-w
+		Do not print reformatted sources to standard output.
+		If a file's formatting is different from gofmt's, overwrite it
+		with gofmt's version.
+
+Debugging support:
+	-cpuprofile filename
+		Write cpu profile to the specified file.
+
+
+The rewrite rule specified with the -r flag must be a string of the form:
+
+	pattern -> replacement
+
+Both pattern and replacement must be valid Go expressions.
+In the pattern, single-character lowercase identifiers serve as
+wildcards matching arbitrary sub-expressions; those expressions
+will be substituted for the same identifiers in the replacement.
+
+When gofmt reads from standard input, it accepts either a full Go program
+or a program fragment.  A program fragment must be a syntactically
+valid declaration list, statement list, or expression.  When formatting
+such a fragment, gofmt preserves leading indentation as well as leading
+and trailing spaces, so that individual sections of a Go program can be
+formatted by piping them through gofmt.
+
+Examples
+
+To check files for unnecessary parentheses:
+
+	gofmt -r '(a) -> a' -l *.go
+
+To remove the parentheses:
+
+	gofmt -r '(a) -> a' -w *.go
+
+To convert the package tree from explicit slice upper bounds to implicit ones:
+
+	gofmt -r 'α[β:len(α)] -> α[β:]' -w $GOROOT/src/pkg
+
+The simplify command
+
+When invoked with -s gofmt will make the following source transformations where possible.
+
+	An array, slice, or map composite literal of the form:
+		[]T{T{}, T{}}
+	will be simplified to:
+		[]T{{}, {}}
+
+	A slice expression of the form:
+		s[a:len(s)]
+	will be simplified to:
+		s[a:]
+
+	A range of the form:
+		for x, _ = range v {...}
+	will be simplified to:
+		for x = range v {...}
+*/
+package main
+
+// BUG(rsc): The implementation of -r is a bit slow.