x/pkgsite: support custom build tags list

[ugorji]

Before filing a bug, please check whether it has been fixed since
the latest release: run "hg pull", "hg update default", rebuild, and
retry
what you did to reproduce the problem.  Thanks.

What steps will reproduce the problem?
If possible, include a link to a program on play.golang.org.
1. Run godoc on a package having some files with build constraints e.g. // +build ignore
2. The files are skipped by godoc and their contents are not reflected in godoc output.
I don't see the files listed either.
3.

What is the expected output?

I expected to see the information in godoc.

What do you see instead?
Nothing.

Which compiler are you using (5g, 6g, 8g, gccgo)?
6g

Which operating system are you using?
Linux

Which version are you using?  (run 'go version')
Running at tip, but go version gives:
go version weekly.2012-03-22 +de7e784537ac

Please provide any additional information below.

[rsc]

Comment 1:

godoc ignores files that say "// +build ignore".
It uses the files that would be built by go build.
That seems like it is working as intended.
Maybe after Go 1 we could give godoc a flag to
allow the specification of additional build tags,
like go build's -tags.
Russ

Labels changed: added priority-later, removed priority-triage.

Status changed to Accepted.

[ugorji]

Comment 2:

That would be nice.
I stumbled upon this because I tagged some of my code which should only run on an
appengine instance with // +build appengine. After that, I couldn't see them anymore
using godoc. My only solution seemed to be to remove the build constraints.

[rsc]

Comment 3:

Labels changed: added go1.1maybe.

[rsc]

Comment 4:

Labels changed: added size-m.

[rsc]

Comment 5:

[The time for maybe has passed.]

Labels changed: removed go1.1maybe.

[adg]

Comment 6:

Labels changed: added godoc.

[rsc]

Comment 7:

Labels changed: added go1.2.

[rsc]

Comment 8:

Labels changed: added feature.

[robpike]

Comment 9:

This would be nice, but it won't happen for Go 1.2.

Labels changed: removed go1.2.

[rsc]

Comment 10:

Labels changed: added go1.3maybe.

[rsc]

Comment 11:

Labels changed: removed feature.

[rsc]

Comment 12:

Labels changed: added release-none, removed go1.3maybe.

[rsc]

Comment 13:

Labels changed: added repo-tools.

[jeffallen]

If you are someone like me who just stumbled across this old bug and are looking for a quick hack to solve your problem right now, use "go get golang.org/x/tools" to get the godoc source code then hack it like this:

diff --git a/godoc/server.go b/godoc/server.go
index 3b452e5e..d231425e 100644
--- a/godoc/server.go
+++ b/godoc/server.go
@@ -64,6 +64,7 @@ func (h *handlerServer) GetPageInfo(abspath, relpath string, mode PageInfoMode,
 	// Note: If goos/goarch aren't set, the current binary's GOOS/GOARCH
 	// are used.
 	ctxt := build.Default
+	ctxt.BuildTags = []string{"vartime"}
 	ctxt.IsAbsPath = pathpkg.IsAbs
 	ctxt.IsDir = func(path string) bool {
 		fi, err := h.c.fs.Stat(filepath.ToSlash(path))

Then use "go build" to build a local copy of godoc that is using the build tags you need.

[gopherbot]

Change https://golang.org/cl/129099 mentions this issue: x/tools/cmd/godoc: add -tags like go build

[SchumacherFM]

Good evening,

as I currently need this feature in godoc to display documentation for specific build tags, I've added it to godoc. It took me a couple of days and I think it is ready for review 😊.
See the CL https://golang.org/cl/129099

Below I've added some printscreens how the design looks like for HTML and CLI.
If there are better ideas to display the build tag information, let me know.

It would be great if some one from the Go Team, etc can review the code.