1 files changed, 26 insertions, 4 deletions
diff --git a/compiler/pragmas.nim b/compiler/pragmas.nim
index 6637a8673..e9f52c71f 100644
--- a/compiler/pragmas.nim
+++ b/compiler/pragmas.nim
@@ -29,7 +29,7 @@ const
     wCompilerProc, wNonReloadable, wCore, wProcVar, wVarargs, wCompileTime, wMerge,
     wBorrow, wImportCompilerProc, wThread,
     wAsmNoStackFrame, wDiscardable, wNoInit, wCodegenDecl,
-    wGensym, wInject, wRaises, wTags, wLocks, wDelegator, wGcSafe,
+    wGensym, wInject, wRaises, wEffectsOf, wTags, wLocks, wDelegator, wGcSafe,
     wConstructor, wLiftLocals, wStackTrace, wLineTrace, wNoDestroy,
     wRequires, wEnsures}
   converterPragmas* = procPragmas
@@ -41,7 +41,7 @@ const
     wDiscardable, wGensym, wInject, wDelegator}
   iteratorPragmas* = declPragmas + {FirstCallConv..LastCallConv, wNoSideEffect, wSideEffect,
     wMagic, wBorrow,
-    wDiscardable, wGensym, wInject, wRaises,
+    wDiscardable, wGensym, wInject, wRaises, wEffectsOf,
     wTags, wLocks, wGcSafe, wRequires, wEnsures}
   exprPragmas* = {wLine, wLocks, wNoRewrite, wGcSafe, wNoSideEffect}
   stmtPragmas* = {wChecks, wObjChecks, wFieldChecks, wRangeChecks,
@@ -59,7 +59,7 @@ const
   lambdaPragmas* = {FirstCallConv..LastCallConv,
     wNoSideEffect, wSideEffect, wNoreturn, wNosinks, wDynlib, wHeader,
     wThread, wAsmNoStackFrame,
-    wRaises, wLocks, wTags, wRequires, wEnsures,
+    wRaises, wLocks, wTags, wRequires, wEnsures, wEffectsOf,
     wGcSafe, wCodegenDecl, wNoInit, wCompileTime}
   typePragmas* = declPragmas + {wMagic, wAcyclic,
     wPure, wHeader, wCompilerProc, wCore, wFinal, wSize, wShallow,
@@ -79,7 +79,7 @@ const
   paramPragmas* = {wNoalias, wInject, wGensym}
   letPragmas* = varPragmas
   procTypePragmas* = {FirstCallConv..LastCallConv, wVarargs, wNoSideEffect,
-                      wThread, wRaises, wLocks, wTags, wGcSafe,
+                      wThread, wRaises, wEffectsOf, wLocks, wTags, wGcSafe,
                       wRequires, wEnsures}
   forVarPragmas* = {wInject, wGensym}
   allRoutinePragmas* = methodPragmas + iteratorPragmas + lambdaPragmas
@@ -779,6 +779,26 @@ proc semCustomPragma(c: PContext, n: PNode): PNode =
     # pragma(arg) -> pragma: arg
     result.transitionSonsKind(n.kind)
 
+proc processEffectsOf(c: PContext, n: PNode; owner: PSym) =
+  proc processParam(c: PContext; n: PNode) =
+    let r = c.semExpr(c, n)
+    if r.kind == nkSym and r.sym.kind == skParam:
+      if r.sym.owner == owner:
+        incl r.sym.flags, sfEffectsDelayed
+      else:
+        localError(c.config, n.info, errGenerated, "parameter cannot be declared as .effectsOf")
+    else:
+      localError(c.config, n.info, errGenerated, "parameter name expected")
+
+  if n.kind notin nkPragmaCallKinds or n.len != 2:
+    localError(c.config, n.info, errGenerated, "parameter name expected")
+  else:
+    let it = n[1]
+    if it.kind in {nkCurly, nkBracket}:
+      for x in items(it): processParam(c, x)
+    else:
+      processParam(c, it)
+
 proc singlePragma(c: PContext, sym: PSym, n: PNode, i: var int,
                   validPragmas: TSpecialWords,
                   comesFromPush, isStatement: bool): bool =
@@ -895,6 +915,8 @@ proc singlePragma(c: PContext, sym: PSym, n: PNode, i: var int,
       of wNoalias:
         noVal(c, it)
         incl(sym.flags, sfNoalias)
+      of wEffectsOf:
+        processEffectsOf(c, it, sym)
       of wThreadVar:
         noVal(c, it)
         incl(sym.flags, {sfThread, sfGlobal})