cmd/go: add another test case for package/module ambiguity in 'go get'

For #37438

Change-Id: Iae00ef7f97144e85f4f710cdb3087c2548b4b8f0
Reviewed-on: https://go-review.googlesource.com/c/go/+/256799
Trust: Bryan C. Mills <[email protected]>
Trust: Jay Conrod <[email protected]>
Run-TryBot: Bryan C. Mills <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Michael Matloob <[email protected]>
Reviewed-by: Jay Conrod <[email protected]>

Author: Bryan C. Mills

src/cmd/go/testdata/mod/example.net_pkgremoved_v0.1.0.txt

@@ -0,0 +1,16 @@
+Written by hand.
+Test module with a root package added in v0.1.0 and removed in v0.2.0.
+
+-- .mod --
+module example.net/pkgremoved
+
+go 1.16
+-- .info --
+{"Version": "v0.1.0"}
+-- go.mod --
+module example.net/pkgremoved
+
+go 1.16
+-- pkgremoved.go --
+// Package pkgremoved exists in v0.1.0.
+package pkgremoved

src/cmd/go/testdata/mod/example.net_pkgremoved_v0.2.0.txt

@@ -0,0 +1,15 @@
+Written by hand.
+Test module with a root package added in v0.1.0 and removed in v0.2.0.
+
+-- .mod --
+module example.net/pkgremoved
+
+go 1.16
+-- .info --
+{"Version": "v0.2.0"}
+-- go.mod --
+module example.net/pkgremoved
+
+go 1.16
+-- README.txt --
+Package pkgremove was removed in v0.2.0.

src/cmd/go/testdata/mod/example.net_pkgremoved_v0.2.1.txt

@@ -0,0 +1,15 @@
+Written by hand.
+Test module with a root package added in v0.1.0 and removed in v0.2.0.
+
+-- .mod --
+module example.net/pkgremoved
+
+go 1.16
+-- .info --
+{"Version": "v0.2.1"}
+-- go.mod --
+module example.net/pkgremoved
+
+go 1.16
+-- README.txt --
+Package pkgremove was removed in v0.2.0.

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

@@ -0,0 +1,38 @@
+# example.net/[email protected] refers to a package.
+go get -d example.net/[email protected]
+
+go list example.net/pkgremoved
+stdout '^example.net/pkgremoved'
+
+# When we resolve a new dependency on example.net/other,
+# it will change the meaning of the path "example.net/pkgremoved"
+# from a package (at v0.1.0) to only a module (at v0.2.0).
+#
+# If we simultaneously 'get' that module at the query "patch", the module should
+# be upgraded to its patch release (v0.2.1) even though it no longer matches a
+# package.
+#
+# BUG(#37438): Today, the pattern is only interpreted as its initial kind
+# (a package), so the 'go get' invocation fails.
+
+! go get -d example.net/pkgremoved@patch example.net/[email protected]
+
+stderr '^go get example.net/pkgremoved@patch: module example.net/pkgremoved@latest found \(v0.2.1\), but does not contain package example.net/pkgremoved$'
+
+
+-- go.mod --
+module example
+
+go 1.16
+
+replace (
+	example.net/other v0.1.0 => ./other
+)
+-- other/go.mod --
+module example.net/other
+
+go 1.16
+
+require example.net/pkgremoved v0.2.0
+-- other/other.go --
+package other