fix include in templates, with prefix operators (#24029)

fixes #12539, refs #21636

`evalInclude` now uses `getPIdent` to check if a symbol isn't `/`
anymore instead of assuming it's an ident, which it's not when used in
templates. Also it just checks if the symbol is `as` now, because there
are other infix operators that could be used like `/../`.

It also works with prefix operators now by copying what was done in
#21636.

compiler/semstmts.nim

@@ -2735,20 +2735,23 @@ proc incMod(c: PContext, n: PNode, it: PNode, includeStmtResult: PNode) =
 proc evalInclude(c: PContext, n: PNode): PNode =
   result = newNodeI(nkStmtList, n.info)
   result.add n
+  template checkAs(it: PNode) =
+    if it.kind == nkInfix and it.len == 3:
+      let op = it[0].getPIdent
+      if op != nil and op.id == ord(wAs):
+        localError(c.config, it.info, "Cannot use '" & it[0].renderTree & "' in 'include'.")
   for i in 0..<n.len:
-    var imp: PNode
     let it = n[i]
-    if it.kind == nkInfix and it.len == 3 and it[0].ident.s != "/":
-      localError(c.config, it.info, "Cannot use '" & it[0].ident.s & "' in 'include'.")
-    if it.kind == nkInfix and it.len == 3 and it[2].kind == nkBracket:
-      let sep = it[0]
-      let dir = it[1]
-      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]:
-        imp[2] = x
+    checkAs(it)
+    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]:
+        checkAs(x)
+        imp[lastPos] = x
         incMod(c, n, imp, result)
     else:
       incMod(c, n, it, result)

tests/modules/mincludeprefix.nim

@@ -0,0 +1 @@
+const bar = 456

tests/modules/mincludetemplate.nim

@@ -0,0 +1 @@
+const foo = 123

tests/modules/tincludeprefix.nim

@@ -0,0 +1,3 @@
+include ./[mincludeprefix, mincludetemplate]
+doAssert foo == 123
+doAssert bar == 456

tests/modules/tincludetemplate.nim

@@ -0,0 +1,5 @@
+# issue #12539
+
+template includePath(n: untyped) = include ../modules/n # But `include n` works
+includePath(mincludetemplate)
+doAssert foo == 123