Simplify new_localvar by putting warning logic in its own function

src/lparser.cpp

@@ -529,15 +529,7 @@ static LocVar *localdebuginfo (FuncState *fs, int vidx) {
 }
 
 
-/*
-** Create a new local variable with the given 'name'. Return its index
-** in the function.
-*/
-static int new_localvar (LexState *ls, TString *name, int line, TypeHint hint = {}) {
-  lua_State *L = ls->L;
-  FuncState *fs = ls->fs;
-  Dyndata *dyd = ls->dyd;
-  Vardesc *var;
+static void checkforshadowing (LexState *ls, FuncState *fs, TString *name, int line) {
   int locals = luaY_nvarstack(fs);
   for (int i = fs->firstlocal; i < locals; i++) {
     Vardesc *desc = getlocalvardesc(fs, i);
@@ -546,11 +538,24 @@ static int new_localvar (LexState *ls, TString *name, int line, TypeHint hint =
     if ((n != "(for state)" && n != "(switch control value)" && n != "(try results)" && n != "(try ok)") && (local && local->varname == name)) { // Got a match.
       throw_warn(ls,
         "duplicate local declaration",
-          luaO_fmt(L, "this shadows the initial declaration of '%s' on line %d.", name->contents, desc->vd.line), line, WT_VAR_SHADOW);
-      L->top.p--; /* pop result of luaO_fmt */
+          luaO_fmt(ls->L, "this shadows the initial declaration of '%s' on line %d.", name->contents, desc->vd.line), line, WT_VAR_SHADOW);
+      ls->L->top.p--; /* pop result of luaO_fmt */
       break;
     }
   }
+}
+
+
+/*
+** Create a new local variable with the given 'name'. Return its index
+** in the function.
+*/
+static int new_localvar (LexState *ls, TString *name, int line, TypeHint hint = {}) {
+  lua_State *L = ls->L;
+  FuncState *fs = ls->fs;
+  Dyndata *dyd = ls->dyd;
+  Vardesc *var;
+  checkforshadowing(ls, fs, name, line);
   luaM_growvector(L, dyd->actvar.arr, dyd->actvar.n + 1,
                   dyd->actvar.size, Vardesc, USHRT_MAX, "local variables");
   var = &dyd->actvar.arr[dyd->actvar.n++];