A special state to track field selection is not necessary.

src/compiler/glslang.l

@@ -58,9 +58,7 @@ static int reserved_word(yyscan_t yyscanner);
 
 %option noyywrap nounput never-interactive
 %option yylineno reentrant bison-bridge
-%option stack
 %option extra-type="TParseContext*"
-%x FIELDS
 
 D           [0-9]
 L           [a-zA-Z_]
@@ -232,7 +230,7 @@ O           [0-7]
 ")"         { return RIGHT_PAREN; }
 ("["|"<:")  { return LEFT_BRACKET; }
 ("]"|":>")  { return RIGHT_BRACKET; }
-"."         { BEGIN(FIELDS); return DOT; }
+"."         { return DOT; }
 "!"         { return BANG; }
 "-"         { return DASH; }
 "~"         { return TILDE; }
@@ -247,16 +245,9 @@ O           [0-7]
 "&"         { return AMPERSAND; }
 "?"         { return QUESTION; }
 
-<FIELDS>{L}({L}|{D})* { 
-    BEGIN(INITIAL);
-    yylval->lex.string = NewPoolTString(yytext); 
-    return FIELD_SELECTION;
-}
-<FIELDS>[ \t\v\f\r] {}
-
-[ \t\v\n\f\r]   {  }
-<*><<EOF>>      { yyterminate(); }
-<*>.            { context->warning(yylineno, "Unknown char", yytext, ""); return 0; }
+[ \t\v\n\f\r] { }
+<<EOF>>       { yyterminate(); }
+.             { context->warning(yylineno, "Unknown char", yytext, ""); return 0; }
 
 %%
 

src/compiler/glslang.y

@@ -116,7 +116,6 @@ extern void yyerror(TParseContext* context, const char* reason);
 %token <lex> SAMPLER2D SAMPLERCUBE SAMPLER_EXTERNAL_OES SAMPLER2DRECT
 
 %token <lex> IDENTIFIER TYPE_NAME FLOATCONSTANT INTCONSTANT BOOLCONSTANT
-%token <lex> FIELD_SELECTION
 %token <lex> LEFT_OP RIGHT_OP
 %token <lex> INC_OP DEC_OP LE_OP GE_OP EQ_OP NE_OP
 %token <lex> AND_OP OR_OP XOR_OP MUL_ASSIGN DIV_ASSIGN ADD_ASSIGN
@@ -322,7 +321,7 @@ postfix_expression
     | function_call {
         $$ = $1;
     }
-    | postfix_expression DOT FIELD_SELECTION {
+    | postfix_expression DOT identifier {
         if ($1->isArray()) {
             context->error($3.line, "cannot apply dot operator to an array", ".");
             context->recover();
@@ -672,13 +671,6 @@ function_identifier
         TFunction *function = new TFunction($1.string, type);
         $$ = function;
     }
-    | FIELD_SELECTION {
-        if (context->reservedErrorCheck($1.line, *$1.string))
-            context->recover();
-        TType type(EbtVoid, EbpUndefined);
-        TFunction *function = new TFunction($1.string, type);
-        $$ = function;
-    }
     ;
 
 unary_expression