Returning a json or gob error directly to the user is generally not
helpful, as it lacks any form of context.
For example, from the json unmarshal of "go env -json":
$ garble build
invalid character 'w' looking for beginning of value
Also improve the error when the user ran garble in the wrong way,
resulting in no shared gob file. The context is now shorter, and we also
include the os.Open error in case it contains any useful details.
While here, apply Go tip's gofmt, which reformatted a godoc list.
For #523.
When someone builds garble from a git clone,
the resulting binary used to not contain any information:
$ garble version
(devel)
Since Go 1.18, VCS information is stamped by default into binaries.
We now print it, alongside any other available build settings:
$ garble version
mvdan.cc/garble (devel)
Build settings:
-compiler gc
CGO_ENABLED 1
GOARCH amd64
GOOS linux
GOAMD64 v3
vcs git
vcs.revision 91ea246349
vcs.time 2022-03-18T13:45:11Z
vcs.modified true
Note that it's still possible for a garble build to contain no useful
version information, such as when built via "go build -buildvcs=false".
However, if a user opts into omitting the information, it's on them to
figure out what version of garble they actually built.
While here, bump test-gotip.
Fixes#491.
We've had confused users a handful of times by now.
And it's reasonable to expect flags to be after the command,
as that's how flags work for cmd/go itself.
I don't think we want to mix our flags with Go's,
or start accepting flags in either place.
Both seem like worse solutions long-term, as they can add confusion.
However, we can quickly give a useful hint when a flag is misplaced.
That should get new users unblocked without asking for help.
We use a regular expression for this purpose,
because it doesn't seem like a FlagSet supports what we need;
to detect whether an argument is one of our flags,
without actually applying its value to the flagset.
Our flagset would also error on Go's flags, which we don't want.
The "reverse" command had many levels of optional arguments:
garble [garble flags] reverse [build flags] [package] [files]
This was pretty confusing,
and could easily lead to people running the command incorrectly:
# note that output.txt isn't a Go package!
garble reverse output.txt
Moreover, it made the handling of Go build flags pretty confusing.
Should the command below work?
garble reverse -tags=mytag
It also made it easy to not notice that one must supply the main package
to properly reverse some text that it produced, like a panic message.
With the package path being implicit,
one could mistakenly provide the wrong package by running garble
in a directory containing a different package.
See #394.
Before, "garble build -h" would print the same as "garble -h", which is
too much and confusing, as it doesn't tell us much about "build".
Now it's far better, and includes the output of "go build -h":
$ garble build -h
usage: garble [garble flags] build [arguments]
This command wraps "go build". Below is its help:
usage: go build [-o output] [build flags] [packages]
Run 'go help build' for details.
We do the same for "garble reverse -h", since it doesn't wrap a Go tool
command.
Previously garble heavily used env vars to share data between processes.
This also makes it easy to share complex data between processes.
The complexity of main.go is considerably reduced.
Rework the features section in the README, leaving optional features at
the end of the list. Simplify the caveats list, too; the build cache and
exported field/method bits only need one point each. Overall, the
section was far too wordy for little reason.
Also redo the help text a bit. There's now a line to briefly introduce
the tool, as well as a link to the README with all the details. Finally,
the flags have shorter and more consistent help strings.
While at it, remove two unused global vars as spotted by staticcheck.
We don't really care about tools other than "compile" and "link". Stop
trying to keep a complete list.
Use "if err := f(); err != nil {" where it makes sense.
Simplify some declarations, and use a better variable name than "fW".
Also remove the -toolexec equivalent, as it's becoming longer now that
we have GARBLE_DIR, and it might become out of date in the future again.
We don't want users to assume it will work forever.
Daniel Martí
lu4p