pkg/subsystem: fix a bug in PathMatcher

It used to be the case that, if a subsystem matches several rule
conditions, it could be returned several times. This has led to
incorrect parent inference results.

2 files changed, 10 insertions, 4 deletions

diff --git a/pkg/subsystem/match.go b/pkg/subsystem/match.go
index ad5d3a257..475222c77 100644
--- a/pkg/subsystem/match.go
+++ b/pkg/subsystem/match.go
@@ -4,7 +4,9 @@
 package subsystem
 
 import (
+	"maps"
 	"regexp"
+	"slices"
 	"strings"
 )
 
@@ -48,7 +50,7 @@ func (p *PathMatcher) register(item *Subsystem) {
 }
 
 func (p *PathMatcher) Match(path string) []*Subsystem {
-	ret := []*Subsystem{}
+	ret := map[*Subsystem]struct{}{}
 	for _, m := range p.matches {
 		if m.exclude != nil && m.exclude.MatchString(path) {
 			continue
@@ -56,9 +58,9 @@ func (p *PathMatcher) Match(path string) []*Subsystem {
 		if m.include != nil && !m.include.MatchString(path) {
 			continue
 		}
-		ret = append(ret, m.object)
+		ret[m.object] = struct{}{}
 	}
-	return ret
+	return slices.Collect(maps.Keys(ret))
 }
 
 func buildMatch(rule PathRule, item *Subsystem) *match {
diff --git a/pkg/subsystem/match_test.go b/pkg/subsystem/match_test.go
index 7c96b0bcd..f2a3c885b 100644
--- a/pkg/subsystem/match_test.go
+++ b/pkg/subsystem/match_test.go
@@ -16,6 +16,10 @@ func TestPathMatcher(t *testing.T) {
 				IncludeRegexp: `^arch/arm/.*$`,
 				ExcludeRegexp: `^arch/arm/boot/dts/.*$`,
 			},
+			// Add a somewhat overlapping rule so that we test that no duplicates are returned.
+			{
+				IncludeRegexp: `^arch/arm/a/.*$`,
+			},
 			{IncludeRegexp: `^drivers/spi/spi-pl022\.c$`},
 			{
 				// nolint:lll
@@ -31,7 +35,7 @@ func TestPathMatcher(t *testing.T) {
 	m := MakePathMatcher([]*Subsystem{arm, docs})
 	assert.ElementsMatch(t, []*Subsystem{arm, docs},
 		m.Match(`Documentation/devicetree/bindings/interrupt-controller/arm,vic.yaml`))
-	assert.ElementsMatch(t, []*Subsystem{arm}, m.Match(`arch/arm/a.c`))
+	assert.ElementsMatch(t, []*Subsystem{arm}, m.Match(`arch/arm/a/a.c`))
 	assert.ElementsMatch(t, []*Subsystem{docs}, m.Match(`Documentation/a/b/c.md`))
 	assert.Empty(t, m.Match(`arch/boot/dts/a.c`))
 }