code review 6996054: cmd/gc: make forward declaration in pure Go package an error

cmd/gc: make forward declaration in pure Go package an error

An error during the compilation can be more precise
than an error at link time.

For 'func init', the error happens always: you can't forward
declare an init func because the name gets mangled.

For other funcs, the error happens only with the special
(and never used by hand) -= flag, which tells 6g the
package is pure go.

The go command now passes -= for pure Go packages.

Fixes issue 3705.

[rsc, 2012-12-22 21:46:29]

Hello ken2 (cc: golang-dev@googlegroups.com),

I'd like you to review this change to
https://code.google.com/p/go/

[rsc, 2012-12-22 21:47:07]

*** Submitted as https://code.google.com/p/go/source/detail?r=bf60b2c842b6 ***

cmd/gc: make forward declaration in pure Go package an error

An error during the compilation can be more precise
than an error at link time.

For 'func init', the error happens always: you can't forward
declare an init func because the name gets mangled.

For other funcs, the error happens only with the special
(and never used by hand) -= flag, which tells 6g the
package is pure go.

The go command now passes -= for pure Go packages.

Fixes issue 3705.

R=ken2
CC=golang-dev
https://codereview.appspot.com/6996054

[remyoudompheng, 2012-12-22 21:48:59]

https://codereview.appspot.com/6996054/diff/2001/src/cmd/go/build.go
File src/cmd/go/build.go (right):

https://codereview.appspot.com/6996054/diff/2001/src/cmd/go/build.go#newcode1314
src/cmd/go/build.go:1314: var rsc = flag.Bool("rsc", false, "rsc")
Did you really intend to add a "rsc" flag?

[rsc, 2012-12-22 21:58:06]

no, sorry. will send you a CL.