fixes #4227

tests/trmacros/tstatic_t_bug.nim

@@ -0,0 +1,24 @@
+discard """
+  output: "optimized"
+"""
+# bug #4227
+type Vector64[N: static[int]] = array[N, int]
+
+proc `*`*[N: static[int]](a: Vector64[N]; b: float64): Vector64[N] =
+  result = a
+
+proc `+=`*[N: static[int]](a: var Vector64[N]; b: Vector64[N]) =
+  echo "regular"
+
+proc linearCombinationMut[N: static[int]](a: float64, v: var Vector64[N], w: Vector64[N])  {. inline .} =
+  echo "optimized"
+
+template rewriteLinearCombinationMut*{v += `*`(w, a)}(a: float64, v: var Vector64, w: Vector64): auto =
+  linearCombinationMut(a, v, w)
+
+proc main() =
+  const scaleVal = 9.0
+  var a, b: Vector64[7]
+  a += b * scaleval
+
+main()