cmd/compile: internal error missing type check

[jayconrod]

What version of Go are you using (go version)?

$ go version
go version devel +c0cfe9687f Thu Mar 14 21:00:20 2019 +0000 darwin/amd64

Does this issue reproduce with the latest release?

No

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/jayconrod/Library/Caches/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/jayconrod/go"
GOPROXY=--redacted--
GORACE=""
GOROOT="/Users/jayconrod/Code/go"
GOTMPDIR=""
GOTOOLDIR="/Users/jayconrod/Code/go/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/Users/jayconrod/go/src/gocloud.dev/go.mod"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/rq/x0692kqj6ml8cvrhcqh5bswc008xj1/T/go-build259363876=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

$ cd ~/go/src
$ git clone https://github.com/google/go-cloud gocloud.dev
$ cd gocloud.dev
$ GO111MODULE=on go test -cover -coverpkg=./... ./blob/azureblob

What did you expect to see?

ok  	gocloud.dev/blob/azureblob	0.666s	coverage: 68.6% of statements in ./...

What did you see instead?

# gocloud.dev/blob/azureblob [gocloud.dev/blob/azureblob.test]
blob/azureblob/azureblob.go:535: internal compiler error: missing typecheck: 
.   AS l(536)
.   .   NAME-uuid..autotmp_1 a(true) l(14) x(0) class(PAUTO) tc(1) used uuid.UUID

goroutine 1 [running]:
runtime/debug.Stack(0x1c03f00, 0xc00009c000, 0x0)
	/Users/jayconrod/Code/go/src/runtime/debug/stack.go:24 +0x9d
cmd/compile/internal/gc.Fatalf(0x1a61921, 0x16, 0xc000b87450, 0x1, 0x1)
	/Users/jayconrod/Code/go/src/cmd/compile/internal/gc/subr.go:190 +0x293
cmd/compile/internal/gc.walkstmt(0xc0009a7a00, 0xc0009a7980)
	/Users/jayconrod/Code/go/src/cmd/compile/internal/gc/walk.go:154 +0xe9a
cmd/compile/internal/gc.walkstmtlist(0xc000b92800, 0x2d, 0x40)
	/Users/jayconrod/Code/go/src/cmd/compile/internal/gc/walk.go:79 +0x46
cmd/compile/internal/gc.walkstmt(0xc0005a8680, 0xc0005a8380)
	/Users/jayconrod/Code/go/src/cmd/compile/internal/gc/walk.go:258 +0x132f
cmd/compile/internal/gc.walkstmtlist(0xc000b92600, 0x2d, 0x40)
	/Users/jayconrod/Code/go/src/cmd/compile/internal/gc/walk.go:79 +0x46
cmd/compile/internal/gc.walk(0xc00058e6e0)
	/Users/jayconrod/Code/go/src/cmd/compile/internal/gc/walk.go:63 +0x3e4
cmd/compile/internal/gc.compile(0xc00058e6e0)
	/Users/jayconrod/Code/go/src/cmd/compile/internal/gc/pgen.go:235 +0x80
cmd/compile/internal/gc.funccompile(0xc00058e6e0)
	/Users/jayconrod/Code/go/src/cmd/compile/internal/gc/pgen.go:221 +0xc2
cmd/compile/internal/gc.Main(0x1a7a1c8)
	/Users/jayconrod/Code/go/src/cmd/compile/internal/gc/main.go:665 +0x305a
main.main()
	/Users/jayconrod/Code/go/src/cmd/compile/main.go:51 +0xad

FAIL	gocloud.dev/blob/azureblob [build failed]

[jayconrod]

A bisect pointed to CL 166983 as being the first bad commit on master. Seems related to the error.

@mdempsky @griesemer Mind taking a look?

[mdempsky]

Minimal repro:

$ cat uuid/uuid.go
package uuid

type UUID string

func New() UUID {
	return Must(NewRandom())
}

func NewRandom() (UUID, error) {
	return "", nil
}

func Must(uuid UUID, err error) UUID {
	return uuid
}

$ cat p.go
package p

import "./uuid"

func f() {
	uuid.New()
}

$ GO111MODULE=off go build p.go
# command-line-arguments
./p.go:6:10: internal compiler error: missing typecheck: 
.   AS l(6)
.   .   NAME-uuid..autotmp_1 a(true) l(6) x(0) class(PAUTO) tc(1) used uuid.UUID

[gopherbot]

Change https://golang.org/cl/168199 mentions this issue: cmd/compile: fix importing rewritten f(g()) calls

[mdempsky]

Thanks for the report, @jayconrod!

[jayconrod]

Sure, thanks for fixing it so quickly!

[gopherbot]

Change https://golang.org/cl/195279 mentions this issue: cmd/go: fix link error for -coverpkg in GOPATH mode

[gopherbot]

Change https://golang.org/cl/195281 mentions this issue: [release-branch.go1.13] cmd/go: fix link error for -coverpkg in GOPATH mode