Rework the mechanism for passing a list of output files from cmd/go to
cmd/cover when running new-style package-scope coverage
instrumentation (-pkgcfg mode). The old scheme passed a single string
with all output files joined together with os.PathListSeparator, but
this scheme is not viable on plan9, where strings containing the
separator character are not permitted when running exec.Command().
Instead, switch cmd/cover to use an arguments file (a file containing
a list of names) to specify names of instrumented output files. This
fixes the cmd/cover test failures on the plan9 builders.
Updates #51430.
Change-Id: I919f5e0a79500e28648fb9177225a9b938e4fdee
Reviewed-on: https://go-review.googlesource.com/c/go/+/436675
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Than McIntosh <thanm@google.com>
Some of the unit tests in Go's "cmd" tree wind up building a separate
copy of the tool being tested, then exercise the freshly built tool as
a way of doing regression tests. The intent is to make sure that "go
test" is testing the current state of the source code, as opposed to
whatever happened to be current when "go install <tool>" was last run.
Doing things this way is unfriendly for coverage testing. If I run "go
test -cover cmd/mumble", and the cmd/mumble test harness builds a
fresh copy of mumble.exe, any runs of that new executable won't
generate coverage data.
This patch updates the test harnesses to use the unit test executable
as a stand-in for the tool itself, so that if "go test -cover" is in
effect, we get the effect of building the tool executable for coverage
as well. Doing this brings up the overall test coverage number for
cmd/cover quite dramatically:
before change:
$ go test -cover .
ok cmd/cover 1.100s coverage: 1.5% of statements
after change:
$ go test -cover .
ok cmd/cover 1.299s coverage: 84.2% of statements
Getting this to work requires a small change in the Go command as
well, to set GOCOVERDIR prior to executing a test binary.
Updates #51430.
Change-Id: Ifcf0ea85773b80fcda794aae3702403ec8e0b733
Reviewed-on: https://go-review.googlesource.com/c/go/+/404299
Reviewed-by: Bryan Mills <bcmills@google.com>
Add a new mode of coverage instrumentation that works as a hybrid
between purely tool-based and purely compiler-based. The cmd/cover
tool still does source-to-source rewriting, but it also generates
information to be used by the compiler to do things like marking
meta-data vars as read-only.
In hybrid mode, the cmd/cover tool is invoked not on a single source
file but on all the files in a package, and is passed a config file
containing the import path of the package in question, along with
other parameters needed for the run. It writes a series of modified
files and an output config file to be passed to the compiler when
compiling the modified files.
Not completely useful by itself, still needs a corresponding set of
changes in the Go command and in the compiler.
Updates #51430.
Change-Id: I0fcbd93a9a8fc25064187b159152486a2549ea54
Reviewed-on: https://go-review.googlesource.com/c/go/+/395896
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
Than McIntosh