cue/load: do not consider anonymous packages when checking package qu…

…alifier

When cue/load is loading a package with an explicit qualifier
we only want to load the files declaring that package name.
However, in the edge case where the qualifier wasn't specified,
we would always consider files which did not declare any package name,
which was an unintended regression from `CUE_EXPERIMENT=modules=0`.

Fixes #3244

Signed-off-by: Roger Peppe <[email protected]>
Change-Id: I64e81bdba5c1be9b35b08af5e72e631adbae6a9d
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1196720
Reviewed-by: Daniel Martí <[email protected]>
TryBot-Result: CUEcueckoo <[email protected]>
Unity-Result: CUE porcuepine <[email protected]>

cmd/cue/cmd/testdata/script/load_with_unnamed_pkg.txtar

@@ -3,15 +3,14 @@
 # path" logic works correctly in the presence of an
 # non-package CUE file, which can never be part
 # of a package.
-# See https://cuelang.org/issue/3244
 
 cd foo
-# TODO(rog): this should succeed
-! exec cue export
-cmp stderr $WORK/want-stderr
--- want-stderr --
-test.example/foo@v0: import failed: no dependency found for package "other.example/m":
-    ./foo.cue:8:8
+exec cue export
+cmp stdout $WORK/want-stdout
+-- want-stdout --
+{
+    "x": 20
+}
 -- cue.mod/gen/other.example/m/m.cue --
 package m
 x: 20

cue/load/search.go

@@ -434,7 +434,7 @@ func appendExpandedUnqualifiedPackagePath(pkgPaths []resolvedPackageArg, origp s
 		pkgName := f.Syntax.PackageName()
 		// 2. if pkgQual is "_", it looks for a package file with no package name.
 		// 3. if there's a package named after ip.Qualifier it chooses that
-		if pkgName == ip.Qualifier || (pkgQual == "_" && pkgName == "") {
+		if (pkgName != "" && pkgName == ip.Qualifier) || (pkgQual == "_" && pkgName == "") {
 			foundQualifier = true
 			return false
 		}