added hack to handle return in single line if statement, still to test it thoroughly

src/lua/llex.c

@@ -44,7 +44,7 @@ static const char *const luaX_tokens [] = {
     "return", "then", "true", "until", "while",
     "//", "..", "...", "==", ">=", "<=", "~=", "!=",
     "+=", "-=", "*=", "/=",
-    "<<", ">>", "::", "<eof>",
+    "<<", ">>", "::", "<eof>", "<eol>"
     "<number>", "<integer>", "<name>", "<string>"
 };
 
@@ -172,6 +172,7 @@ void luaX_setinput (lua_State *L, LexState *ls, ZIO *z, TString *source,
   ls->lastline = 1;
   ls->source = source;
   ls->envn = luaS_newliteral(L, LUA_ENV);  /* get env name */
+  ls->ignorenewline = 1;
   luaZ_resizebuffer(ls->L, ls->buff, LUA_MINBUFFER);  /* initialize buffer */
 }
 
@@ -432,7 +433,9 @@ static int llex (LexState *ls, SemInfo *seminfo) {
     switch (ls->current) {
       case '\n': case '\r': {  /* line breaks */
         inclinenumber(ls);
-        break;
+        if (ls->ignorenewline)
+          break;
+        return TK_EOL;
       }
       case ' ': case '\f': case '\t': case '\v': {  /* spaces */
         next(ls);

src/lua/llex.h

@@ -33,7 +33,7 @@ enum RESERVED {
   TK_IDIV, TK_CONCAT, TK_DOTS, TK_EQ, TK_GE, TK_LE, TK_NE, TK_NE2,
   TK_ASSADD, TK_ASSSUB, TK_ASSMUL, TK_ASSDIV, TK_ASSMOD,
   TK_SHL, TK_SHR,
-  TK_DBCOLON, TK_EOS,
+  TK_DBCOLON, TK_EOS, TK_EOL,
   TK_FLT, TK_INT, TK_NAME, TK_STRING
 };
 
@@ -57,6 +57,7 @@ typedef struct Token {
 /* state of the lexer plus state of the parser when shared by all
    functions */
 typedef struct LexState {
+  int ignorenewline;
   int current;  /* current character (charint) */
   int linenumber;  /* input line counter */
   int lastline;  /* line of last token 'consumed' */

src/lua/lparser.c

@@ -589,6 +589,8 @@ static int block_follow (LexState *ls, int withuntil) {
     case TK_ELSE: case TK_ELSEIF:
     case TK_END: case TK_EOS:
       return 1;
+    case TK_EOL:
+      return ls->ignorenewline ? 0 : 1;
     case TK_UNTIL: return withuntil;
     default: return 0;
   }
@@ -1431,19 +1433,22 @@ static void inline_if(LexState* ls, expdesc* v)
   enterblock(fs, &bl, 0);
   jf = v->f;
 
-  /* handling return manually because otherwise any valid LHS
-  would be parsed as return value for return statement */
-  if (ls->t.token == TK_RETURN)
-    retstat(ls);
-  else
-    statlist(ls);  /* parse true block */
+  ls->ignorenewline = 0;
+  statlist(ls);  /* parse true block */
+  ls->ignorenewline = 1;
+  while (testnext(ls, TK_EOL));
 
   leaveblock(fs);
 
   luaK_patchtohere(fs, jf);
 
   if (testnext(ls, TK_ELSE))
+  {
+    ls->ignorenewline = 0;
     block(ls);  /* 'else' part */
+    ls->ignorenewline = 1;
+    while (testnext(ls, TK_EOL));
+  }
 }
 
 static int test_then_block (LexState *ls, int *escapelist) {
@@ -1590,7 +1595,7 @@ static void retstat (LexState *ls) {
   FuncState *fs = ls->fs;
   expdesc e;
   int first, nret;  /* registers with returned values */
-  if (block_follow(ls, 1) || ls->t.token == ';')
+  if (block_follow(ls, 1) || ls->t.token == ';' || (ls->t.token == TK_EOL && !ls->ignorenewline))
     first = nret = 0;  /* return no values */
   else {
     nret = explist(ls, &e);  /* optional return values */