code review 62000045: go.tools/go/loader: add AllowTypeErrors flag.

go.tools/go/loader: add AllowTypeErrors flag.

If this flag is set, (*Config).Load will not return an
error even if some packages had type errors.  Each individual
PackageInfo can be queried for its error state, now exposed as
TypeError.

In addition, each PackageInfo exposes whether it is
"transitively error-free".  ssa.Create skips packages without
this flag since it is required for SSA construction.

+ Test.

[adonovan, 2014-02-12 17:44:43]

Hello gri@golang.org (cc: golang-codereviews@googlegroups.com),

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

[gri, 2014-02-18 22:53:49]

LGTM

https://codereview.appspot.com/62000045/diff/60001/go/loader/importer_test.go
File go/loader/importer_test.go (right):

https://codereview.appspot.com/62000045/diff/60001/go/loader/importer_test.go...
go/loader/importer_test.go:134: contents = `package a; import _ "b"; import _
"e"`
import (_ "b"; _ "e")

https://codereview.appspot.com/62000045/diff/60001/go/loader/importer_test.go...
go/loader/importer_test.go:138: contents = `package c; func f() { _ = int(false)
}` // internal type error
why internal?

https://codereview.appspot.com/62000045/diff/60001/go/loader/loader.go
File go/loader/loader.go (right):

https://codereview.appspot.com/62000045/diff/60001/go/loader/loader.go#newcod...
go/loader/loader.go:472: // TODO(adonovan): treat parse errors as recoverable
too.
really? seems dangerous

https://codereview.appspot.com/62000045/diff/60001/go/loader/util.go
File go/loader/util.go (right):

https://codereview.appspot.com/62000045/diff/60001/go/loader/util.go#newcode24
go/loader/util.go:24: // This function is a var as a concession to testing.
is stored in a variable as a

[adonovan, 2014-02-19 00:42:45]

https://codereview.appspot.com/62000045/diff/60001/go/loader/importer_test.go
File go/loader/importer_test.go (right):

https://codereview.appspot.com/62000045/diff/60001/go/loader/importer_test.go...
go/loader/importer_test.go:134: contents = `package a; import _ "b"; import _
"e"`
On 2014/02/18 22:53:50, gri wrote:
> import (_ "b"; _ "e")

Done.

https://codereview.appspot.com/62000045/diff/60001/go/loader/importer_test.go...
go/loader/importer_test.go:138: contents = `package c; func f() { _ = int(false)
}` // internal type error
On 2014/02/18 22:53:50, gri wrote:
> why internal?

I've rephrased it as: "type error within function body", i.e. the export data is
intact.

https://codereview.appspot.com/62000045/diff/60001/go/loader/loader.go
File go/loader/loader.go (right):

https://codereview.appspot.com/62000045/diff/60001/go/loader/loader.go#newcod...
go/loader/loader.go:472: // TODO(adonovan): treat parse errors as recoverable
too.
On 2014/02/18 22:53:50, gri wrote:
> really? seems dangerous

What I mean is: we don't give up loading the whole program just because one file
has a type error, so why should we do the same for parse errors?

https://codereview.appspot.com/62000045/diff/60001/go/loader/util.go
File go/loader/util.go (right):

https://codereview.appspot.com/62000045/diff/60001/go/loader/util.go#newcode24
go/loader/util.go:24: // This function is a var as a concession to testing.
On 2014/02/18 22:53:50, gri wrote:
> is stored in a variable as a 

Done.

[adonovan, 2014-02-19 00:43:16]

*** Submitted as
https://code.google.com/p/go/source/detail?r=e62965177ee2&repo=tools ***

go.tools/go/loader: add AllowTypeErrors flag.

If this flag is set, (*Config).Load will not return an
error even if some packages had type errors.  Each individual
PackageInfo can be queried for its error state, now exposed as
TypeError.

In addition, each PackageInfo exposes whether it is
"transitively error-free".  ssa.Create skips packages without
this flag since it is required for SSA construction.

+ Test.

LGTM=gri
R=gri
CC=golang-codereviews
https://codereview.appspot.com/62000045