import brackets support as and prefixes [backport] (#21636)

* import brackets support `as` and prefixes

fixes #21635

* copyTree -> copyNode

compiler/importer.nim

@@ -323,22 +323,24 @@ proc evalImport*(c: PContext, n: PNode): PNode =
   result = newNodeI(nkImportStmt, n.info)
   for i in 0..<n.len:
     let it = n[i]
-    if it.kind == nkInfix and it.len == 3 and it[2].kind == nkBracket:
-      let sep = it[0]
-      let dir = it[1]
-      var imp = newNodeI(nkInfix, it.info)
-      imp.add sep
-      imp.add dir
-      imp.add sep # dummy entry, replaced in the loop
-      for x in it[2]:
+    if it.kind in {nkInfix, nkPrefix} and it[^1].kind == nkBracket:
+      let lastPos = it.len - 1
+      var imp = copyNode(it)
+      newSons(imp, it.len)
+      for i in 0 ..< lastPos: imp[i] = it[i]
+      imp[lastPos] = imp[0] # dummy entry, replaced in the loop
+      for x in it[lastPos]:
         # transform `a/b/[c as d]` to `/a/b/c as d`
         if x.kind == nkInfix and x[0].ident.s == "as":
-          let impAs = copyTree(x)
-          imp[2] = x[1]
+          var impAs = copyNode(x)
+          newSons(impAs, 3)
+          impAs[0] = x[0]
+          imp[lastPos] = x[1]
           impAs[1] = imp
-          impMod(c, imp, result)
+          impAs[2] = x[2]
+          impMod(c, impAs, result)
         else:
-          imp[2] = x
+          imp[lastPos] = x
           impMod(c, imp, result)
     else:
       impMod(c, it, result)

tests/modules/timportas.nim

@@ -2,15 +2,20 @@ discard """
     action: run
 """
 
-import .. / modules / [definitions as foo]
-import .. / modules / definitions as foo
+import .. / modules / [mexporta as a1, definitions as foo1]
+import .. / modules / definitions as foo2
+import ./[mexporta as a2, definitions as foo3]
 import std / times as bar
 from times as bar2 import nil
 import times as bar3 except convert
 import definitions as baz
 
-discard foo.v
+discard foo1.v
+discard foo2.v
+discard foo3.v
 discard bar.now()
 discard bar2.now()
 discard bar3.now()
 discard baz.v
+discard a1.xyz
+discard a2.xyz