cmd/go/internal/modload: fix swapped paths in error message

Updates #33879

Change-Id: Ifc91490b1cb791fdf5ffe69ef81c0ec0e6cbecc3
Reviewed-on: https://go-review.googlesource.com/c/go/+/191997
Run-TryBot: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Alexander Rakoczy <alex@golang.org>

src/cmd/go/internal/modload/load.go

@@ -1140,7 +1140,7 @@ func (r *mvsReqs) required(mod module.Version) ([]module.Version, error) {
 	if mpath := f.Module.Mod.Path; mpath != origPath && mpath != mod.Path {
 		return nil, module.VersionError(mod, fmt.Errorf(`parsing go.mod:
 	module declares its path as: %s
-	        but was required as: %s`, mod.Path, mpath))
+	        but was required as: %s`, mpath, mod.Path))
 	}
 	if f.Go != nil {
 		r.versions.LoadOrStore(mod, f.Go.Version)

src/cmd/go/testdata/mod/example.com_badchain_c_v1.1.0.txt

 example.com/badchain/c v1.1.0
 
 -- .mod --
-module example.com/badchain/wrong
+module badchain.example.com/c
 -- .info --
 {"Version":"v1.1.0"}
 -- c.go --

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

@@ -58,28 +58,28 @@ func Test(t *testing.T) {}
 -- update-main-expected --
 go get: example.com/badchain/c@v1.0.0 updating to
 	example.com/badchain/c@v1.1.0: parsing go.mod:
-	module declares its path as: example.com/badchain/c
-	        but was required as: example.com/badchain/wrong
+	module declares its path as: badchain.example.com/c
+	        but was required as: example.com/badchain/c
 -- update-a-expected --
 go get: example.com/badchain/a@v1.1.0 requires
 	example.com/badchain/b@v1.1.0 requires
 	example.com/badchain/c@v1.1.0: parsing go.mod:
-	module declares its path as: example.com/badchain/c
-	        but was required as: example.com/badchain/wrong
+	module declares its path as: badchain.example.com/c
+	        but was required as: example.com/badchain/c
 -- list-expected --
 go: example.com/badchain/a@v1.1.0 requires
 	example.com/badchain/b@v1.1.0 requires
 	example.com/badchain/c@v1.1.0: parsing go.mod:
-	module declares its path as: example.com/badchain/c
-	        but was required as: example.com/badchain/wrong
+	module declares its path as: badchain.example.com/c
+	        but was required as: example.com/badchain/c
 -- list-missing-expected --
 go: m/use imports
 	example.com/badchain/c: example.com/badchain/c@v1.1.0: parsing go.mod:
-	module declares its path as: example.com/badchain/c
-	        but was required as: example.com/badchain/wrong
+	module declares its path as: badchain.example.com/c
+	        but was required as: example.com/badchain/c
 -- list-missing-test-expected --
 go: m/testuse tested by
 	m/testuse.test imports
 	example.com/badchain/c: example.com/badchain/c@v1.1.0: parsing go.mod:
-	module declares its path as: example.com/badchain/c
-	        but was required as: example.com/badchain/wrong
+	module declares its path as: badchain.example.com/c
+	        but was required as: example.com/badchain/c