fix tensor merge (#13053)

convert/tensor_test.go

@@ -3,8 +3,10 @@ package convert
 import (
 	"bytes"
 	"encoding/binary"
+	"fmt"
 	"io"
 	"iter"
+	"math/rand/v2"
 	"slices"
 	"strings"
 	"testing"
@@ -951,3 +953,45 @@ func TestMerge(t *testing.T) {
 		}
 	})
 }
+
+func TestMergeOrder(t *testing.T) {
+	for range 8 {
+		t.Run("", func(t *testing.T) {
+			tensors := make([]Tensor, 16)
+			for i := range tensors {
+				tensors[i] = &fakeTensor{
+					name:  fmt.Sprintf("layer.%d.weight", i),
+					shape: []uint64{1},
+					data:  []float32{float32(i)},
+				}
+			}
+
+			rand.Shuffle(len(tensors), func(i, j int) {
+				tensors[i], tensors[j] = tensors[j], tensors[i]
+			})
+
+			matched, unmatched := mergeTensors(tensors, merge{"layer.*.weight", "layer.weight"})
+			if len(unmatched) != 0 {
+				t.Error("expected no remaining tensors, got", len(unmatched))
+			}
+
+			if len(matched) != 1 {
+				t.Error("expected 1 merged tensor, got", len(matched))
+			}
+
+			var b bytes.Buffer
+			if _, err := matched[0].WriteTo(&b); err != nil {
+				t.Fatal(err)
+			}
+
+			var f32s [16]float32
+			if err := binary.Read(&b, binary.LittleEndian, &f32s); err != nil {
+				t.Fatal(err)
+			}
+
+			if !slices.IsSorted(f32s[:]) {
+				t.Errorf("merged tensor data is not in order: %+v", f32s)
+			}
+		})
+	}
+}