duplicate warnings share one format

1 files changed, 19 insertions, 2 deletions

diff --git a/internal/engine/facts.go b/internal/engine/facts.go
index c510b20..f8fde89 100644
--- a/internal/engine/facts.go
+++ b/internal/engine/facts.go
@@ -5,6 +5,7 @@ package engine
 import (
 	"context"
 	"errors"
+	"io/fs"
 	"path/filepath"
 	"sort"
 	"strings"
@@ -73,11 +74,27 @@ func (run *matchRun) drainDupErrors() {
 	defer run.mu.Unlock()
 	for _, idx := range run.dupIdx {
 		for _, ce := range idx.Errors() {
-			run.warn = append(run.warn, "duplicate: "+xdg.Abbrev(ce.Path)+": "+ce.Err.Error())
+			run.warn = append(run.warn, dupWarning(ce))
 		}
 	}
 }
 
+// dupWarning is the one form of a duplicate warning (triage 6): "duplicate:
+// PATH: cause", the path abbreviated like every other one shown, and an OS
+// error's cause without the raw path it would repeat.
+func dupWarning(err error) string {
+	var ce dup.CandidateError
+	if !errors.As(err, &ce) {
+		return "duplicate: " + err.Error()
+	}
+	cause := ce.Err.Error()
+	var pe *fs.PathError
+	if errors.As(ce.Err, &pe) {
+		cause = pe.Op + ": " + pe.Err.Error()
+	}
+	return "duplicate: " + xdg.Abbrev(ce.Path) + ": " + cause
+}
+
 // dupIndex returns the shared *dup.Index for the resolved, sorted extra
 // directories named by key, building it exactly once across every
 // concurrent caller that asks for the same key.
@@ -95,7 +112,7 @@ func (run *matchRun) dupIndex(key string, dirs []string) *dup.Index {
 		run.mu.Lock()
 		run.dupIdx[key] = idx
 		for _, err := range errs {
-			run.warn = append(run.warn, "duplicate: "+err.Error())
+			run.warn = append(run.warn, dupWarning(err))
 		}
 		run.mu.Unlock()
 	})