code review 1734047: cgo: various bug fixes

cgo: various bug fixes

* remember #defined names, so that C.stdout can refer
  to the real name (on OS X) __stdoutp.
* better handling of #defined constant expressions
* allow n, err = C.strtol("asdf", 0, 123) to get errno as os.Error
* write all output files to current directory
* don't require gcc output if there was no input

Fixes issue 533.
Fixes issue 709.
Fixes issue 756.

[rsc, 2010-07-13 21:37:11]

Hello r (cc: dho, golang-dev@googlegroups.com, iant),

I'd like you to review this change.

[r, 2010-07-13 22:44:03]

LGTM

i've asked for more doc-style comments. this code is unusual enough to deserve
them. there's a lot going on

http://codereview.appspot.com/1734047/diff/12001/13008
File src/cmd/cgo/ast.go (right):

http://codereview.appspot.com/1734047/diff/12001/13008#newcode38
src/cmd/cgo/ast.go:38: func (f *File) ReadGo(name string) {
worth a doc-style comment?

http://codereview.appspot.com/1734047/diff/12001/13010
File src/cmd/cgo/gcc.go (right):

http://codereview.appspot.com/1734047/diff/12001/13010#newcode59
src/cmd/cgo/gcc.go:59: func (p *Package) Translate(f *File) {
comment?

http://codereview.appspot.com/1734047/diff/12001/13010#newcode72
src/cmd/cgo/gcc.go:72: func (p *Package) loadDefines(f *File) {
comment?

http://codereview.appspot.com/1734047/diff/12001/13010#newcode108
src/cmd/cgo/gcc.go:108: func (p *Package) guessKinds(f *File) []*Name {
comment?

http://codereview.appspot.com/1734047/diff/12001/13010#newcode368
src/cmd/cgo/gcc.go:368: func (p *Package) rewriteRef(f *File) {
comment?

http://codereview.appspot.com/1734047/diff/12001/13011
File src/cmd/cgo/main.go (right):

http://codereview.appspot.com/1734047/diff/12001/13011#newcode42
src/cmd/cgo/main.go:42: ExpFunc  []*ExpFunc
comment?

http://codereview.appspot.com/1734047/diff/12001/13012
File src/cmd/cgo/out.go (right):

http://codereview.appspot.com/1734047/diff/12001/13012#newcode37
src/cmd/cgo/out.go:37: fmt.Fprintf(fgo2, "import \"unsafe\"\n\n")
how about
const NL = "\n\n"
fmt.Fprintf(fgo2, `import "unsafe"` + NL)

it's also fine as is

http://codereview.appspot.com/1734047/diff/12001/13012#newcode275
src/cmd/cgo/out.go:275: println("NO EXPORTS")
d

[rsc, 2010-07-14 20:34:26]

added comments
will test again and submit shortly

[r2, 2010-07-14 20:36:39]

much better. thanks.

LGTM

[rsc, 2010-07-15 00:17:56]

*** Submitted as http://code.google.com/p/go/source/detail?r=8983152ecd85 ***

cgo: various bug fixes

* remember #defined names, so that C.stdout can refer
  to the real name (on OS X) __stdoutp.
* better handling of #defined constant expressions
* allow n, err = C.strtol("asdf", 0, 123) to get errno as os.Error
* write all output files to current directory
* don't require gcc output if there was no input

Fixes issue 533.
Fixes issue 709.
Fixes issue 756.

R=r
CC=dho, golang-dev, iant
http://codereview.appspot.com/1734047