[release-branch.go1.16] cmd/go: allow '+' in package import paths in module mode

This change upgrades x/mod to pull in the fix from CL 300152.

Updates #44776.
Fixes #44885.

Change-Id: I273f41df2abfff76d91315b7f19fce851c8770d8
Reviewed-on: https://go-review.googlesource.com/c/go/+/300176
Trust: Bryan C. Mills <[email protected]>
Run-TryBot: Bryan C. Mills <[email protected]>
Reviewed-by: Jay Conrod <[email protected]>
TryBot-Result: Go Bot <[email protected]>
(cherry picked from commit d33e219)
Reviewed-on: https://go-review.googlesource.com/c/go/+/300153

Author: Bryan C. Mills

src/cmd/go.mod

@@ -6,7 +6,7 @@ require (
 	github.com/google/pprof v0.0.0-20201203190320-1bf35d6f28c2
 	golang.org/x/arch v0.0.0-20201008161808-52c3e6f60cff
 	golang.org/x/crypto v0.0.0-20201016220609-9e8e0b390897
-	golang.org/x/mod v0.4.2-0.20210302225053-d515b24adc21
+	golang.org/x/mod v0.4.2-0.20210325185522-dbbbf8a3c6ea
 	golang.org/x/sys v0.0.0-20201204225414-ed752295db88 // indirect
 	golang.org/x/tools v0.0.0-20210107193943-4ed967dd8eff
 )

src/cmd/go.sum

@@ -14,8 +14,8 @@ golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPh
 golang.org/x/crypto v0.0.0-20201016220609-9e8e0b390897 h1:pLI5jrR7OSLijeIDcmRxNmw2api+jEfxLoykJVice/E=
 golang.org/x/crypto v0.0.0-20201016220609-9e8e0b390897/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/mod v0.3.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
-golang.org/x/mod v0.4.2-0.20210302225053-d515b24adc21 h1:FnWKa8BJXkVQ+16E52jkfBOJPx2cG8y/6X376nOgSM4=
-golang.org/x/mod v0.4.2-0.20210302225053-d515b24adc21/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
+golang.org/x/mod v0.4.2-0.20210325185522-dbbbf8a3c6ea h1:zAn46O7Vmm6KdLXx+635hPZSArrt/wNctv4Ab70Jw3k=
+golang.org/x/mod v0.4.2-0.20210325185522-dbbbf8a3c6ea/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.0.0-20201021035429-f5854403a974/go.mod h1:sp8m0HH+o8qH0wwXwYZr8TS3Oi6o0r6Gce1SSxlDquU=

src/cmd/go/testdata/script/mod_invalid_path_plus.txt

@@ -0,0 +1,32 @@
+# https://golang.org/issue/44776
+# The '+' character should be disallowed in module paths, but allowed in package
+# paths within valid modules.
+
+go get -d example.net/cmd
+go list example.net/cmd/x++
+
+! go list -versions -m 'example.net/bad++'
+stderr '^go list -m: module example.net/bad\+\+: malformed module path "example.net/bad\+\+": invalid char ''\+''$'
+
+# TODO(bcmills): 'go get -d example.net/cmd/x++' should also work, but currently
+# it does not. This might be fixed by https://golang.org/cl/297891.
+! go get -d example.net/cmd/x++
+stderr '^go get: malformed module path "example.net/cmd/x\+\+": invalid char ''\+''$'
+
+-- go.mod --
+module example.com/m
+
+go 1.16
+
+replace (
+	example.net/cmd => ./cmd
+)
+
+-- cmd/go.mod --
+module example.net/cmd
+
+go 1.16
+-- cmd/x++/main.go --
+package main
+
+func main() {}

src/cmd/vendor/golang.org/x/mod/module/module.go

@@ -28,7 +28,7 @@ golang.org/x/arch/x86/x86asm
 golang.org/x/crypto/ed25519
 golang.org/x/crypto/ed25519/internal/edwards25519
 golang.org/x/crypto/ssh/terminal
-# golang.org/x/mod v0.4.2-0.20210302225053-d515b24adc21
+# golang.org/x/mod v0.4.2-0.20210325185522-dbbbf8a3c6ea
 ## explicit
 golang.org/x/mod/internal/lazyregexp
 golang.org/x/mod/modfile