Allow {.doctype.} in Nim 1.6 w/o implementation (#21909)

compiler/pragmas.nim

@@ -52,7 +52,7 @@ const
     wDeprecated,
     wPragma, wEmit, wUnroll,
     wLinearScanEnd, wPatterns, wTrMacros, wEffects, wNoForward, wReorder, wComputedGoto,
-    wExperimental, wThis, wUsed, wInvariant, wAssume, wAssert}
+    wExperimental, wDoctype, wThis, wUsed, wInvariant, wAssume, wAssert}
   stmtPragmasTopLevel* = {wChecks, wObjChecks, wFieldChecks, wRangeChecks,
     wBoundChecks, wOverflowChecks, wNilChecks, wStaticBoundchecks,
     wStyleChecks, wAssertions,
@@ -1213,6 +1213,11 @@ proc singlePragma(c: PContext, sym: PSym, n: PNode, i: var int,
         if not isTopLevel(c):
           localError(c.config, n.info, "'experimental' pragma only valid as toplevel statement or in a 'push' environment")
         processExperimental(c, it)
+      of wDoctype:
+        if not isTopLevel(c):
+          localError(c.config, n.info, "\"doctype\" pragma only valid as top-level statement")
+        message(c.config, it.info, hintUser,
+                "doctype is not really implemented in Nim 1")
       of wThis:
         if it.kind in nkPragmaCallKinds and it.len == 2:
           c.selfName = considerQuotedIdent(c, it[1])

compiler/wordrecg.nim

@@ -80,7 +80,7 @@ type
     wLocalPassc = "localPassC", wBorrow = "borrow", wDiscardable = "discardable",
     wFieldChecks = "fieldChecks", wSubsChar = "subschar", wAcyclic = "acyclic",
     wShallow = "shallow", wUnroll = "unroll", wLinearScanEnd = "linearScanEnd",
-    wComputedGoto = "computedGoto", wExperimental = "experimental",
+    wComputedGoto = "computedGoto", wExperimental = "experimental", wDoctype = "doctype",
     wWrite = "write", wGensym = "gensym", wInject = "inject", wDirty = "dirty",
     wInheritable = "inheritable", wThreadVar = "threadvar", wEmit = "emit",
     wAsmNoStackFrame = "asmNoStackFrame", wImplicitStatic = "implicitStatic",