Unpack mSlice tupleconstr for static openarrays (#20615)

compiler/semmacrosanity.nim

@@ -66,6 +66,27 @@ proc annotateType*(n: PNode, t: PType; conf: ConfigRef) =
         if i >= x.len: globalError conf, n.info, "invalid field at index " & $i
         else: annotateType(n[i], x[i], conf)
     elif x.kind == tyProc and x.callConv == ccClosure:
+      n.typ = t
+    elif x.kind == tyOpenArray: # `opcSlice` transforms slices into tuples
+      if n.kind == nkTupleConstr:
+        let
+          bracketExpr = newNodeI(nkBracket, n.info)
+          left = int n[1].intVal
+          right = int n[2].intVal
+        bracketExpr.flags = n.flags
+        case n[0].kind # is this a string slice or a array slice
+        of nkStrKinds:
+          for i in left..right:
+            bracketExpr.add newIntNode(nkCharLit, BiggestInt n[0].strVal[i])
+            annotateType(bracketExpr[^1], t[0], conf)
+        of nkBracket:
+          for i in left..right:
+            bracketExpr.add n[0][i]
+            annotateType(bracketExpr[^1], t[0], conf)
+        else:
+          globalError(conf, n.info, "Incorrectly generated tuple constr")
+        n[] = bracketExpr[]
+
       n.typ = t
     else:
       globalError(conf, n.info, "() must have a tuple type")

tests/views/tconst_views.nim

@@ -24,3 +24,14 @@ proc `$`(x: openArray[int]): string =
 echo c
 echo c2.data
 
+
+type MyObj = object
+  data: openarray[char]
+
+const
+  val1 = Foo(data: toOpenArray([1, 2, 3], 1, 1))
+  val2 = Foo(data: toOpenArray([1, 2, 3], 0, 2))
+  val3 = MyObj(data: "Hello".toOpenArray(0, 2))
+assert val1.data == [2]
+assert val2.data == [1, 2, 3]
+assert val3.data == "Hel"

tests/vm/topenarrays.nim

@@ -35,6 +35,10 @@ static:
   assert arr.toOpenArray(3, 4).toOpenArray(0, 0) == [1]
 
 
+proc doThing(s: static openArray[int]) = discard
+
+doThing([10, 20, 30].toOpenArray(0, 0))
+
 # bug #19969
 proc f(): array[1, byte] =
   var a: array[1, byte]