Rewrite in order to not introduce a new node kind.

compiler/ast.nim

@@ -221,7 +221,6 @@ type
     nkGotoState,          # used for the state machine (for iterators)
     nkState,              # give a label to a code section (for iterators)
     nkBreakState,         # special break statement for easier code generation
-    nkUnderscore,         # underscore inside a tuple unpack ``(_, x) = foo()``
   TNodeKinds* = set[TNodeKind]
 
 type

compiler/lookups.nim

@@ -20,7 +20,6 @@ proc considerQuotedIdent*(n: PNode): PIdent =
   case n.kind
   of nkIdent: result = n.ident
   of nkSym: result = n.sym.name
-  of nkUnderscore: result = getIdent"_"
   of nkAccQuoted:
     case n.len
     of 0:

compiler/parser.nim

@@ -296,14 +296,14 @@ proc colcom(p: var TParser, n: PNode) =
   skipComment(p, n)
 
 proc parseSymbol(p: var TParser, allowNil = false): PNode =
-  #| symbol = '`' (KEYW|IDENT|literal|(operator|'('|')'|'['|']'|'{'|'}'|'='|'_')+)+ '`'
+  #| symbol = '`' (KEYW|IDENT|literal|(operator|'('|')'|'['|']'|'{'|'}'|'=')+)+ '`'
   #|        | IDENT | 'addr' | 'type'
   case p.tok.tokType
   of tkSymbol, tkAddr, tkType:
     result = newIdentNodeP(p.tok.ident, p)
     getTok(p)
   of tkUnderscore:
-    result = newNodeP(nkUnderscore, p)
+    result = newIdentNodeP(getIdent("_"), p)
     getTok(p)
   of tkAccent:
     result = newNodeP(nkAccQuoted, p)
@@ -647,7 +647,7 @@ proc identOrLiteral(p: var TParser, mode: TPrimaryMode): PNode =
     result = newNodeP(nkNilLit, p)
     getTok(p)
   of tkUnderscore:
-    result = newNodeP(nkUnderscore, p)
+    result = newIdentNodeP(getIdent("_"), p)
     getTok(p)
   of tkParLe:
     # () constructor

compiler/renderer.nim

@@ -349,7 +349,6 @@ proc atom(n: PNode): string =
     else:
       result = litAux(n, (cast[PInt64](addr(n.floatVal)))[], 8) & "\'f64"
   of nkNilLit: result = "nil"
-  of nkUnderscore: result = "_"
   of nkType:
     if (n.typ != nil) and (n.typ.sym != nil): result = n.typ.sym.name.s
     else: result = "[type node]"
@@ -806,7 +805,7 @@ proc gsub(g: var TSrcGen, n: PNode, c: TContext) =
   of nkTripleStrLit: putRawStr(g, tkTripleStrLit, n.strVal)
   of nkEmpty: discard
   of nkType: put(g, tkInvalid, atom(n))
-  of nkSym, nkIdent, nkUnderscore: gident(g, n)
+  of nkSym, nkIdent: gident(g, n)
   of nkIntLit: put(g, tkIntLit, atom(n))
   of nkInt8Lit: put(g, tkInt8Lit, atom(n))
   of nkInt16Lit: put(g, tkInt16Lit, atom(n))

compiler/semstmts.nim

@@ -340,6 +340,10 @@ proc checkNilable(v: PSym) =
     elif tfNotNil in v.typ.flags and tfNotNil notin v.ast.typ.flags:
       message(v.info, warnProveInit, v.name.s)
 
+proc isDiscardUnderscore(n: PNode): bool =
+  if n.kind != nkIdent: return false
+  return n.ident.s == "_"
+
 proc semVarOrLet(c: PContext, n: PNode, symkind: TSymKind): PNode =
   var b: PNode
   result = copyNode(n)
@@ -404,7 +408,7 @@ proc semVarOrLet(c: PContext, n: PNode, symkind: TSymKind): PNode =
     for j in countup(0, length-3):
       var v = semIdentDef(c, a.sons[j], symkind)
       if sfGenSym notin v.flags and
-         a.sons[j].kind != nkUnderscore: addInterfaceDecl(c, v)
+         not isDiscardUnderscore(a.sons[j]): addInterfaceDecl(c, v)
       when oKeepVariableNames:
         if c.inUnrolledContext > 0: v.flags.incl(sfShadowed)
         else: