commit 588794e66871c1042ab96a644b0da19681268e78
Author: jiang <address@hidden>
Date:   Sun Jun 22 15:28:34 2014 +0800

    Add warning

diff --git a/libtcc.c b/libtcc.c
index d761582..0f8477c 100644
--- a/libtcc.c
+++ b/libtcc.c
@@ -1404,8 +1404,9 @@ static const FlagDef warning_defs[] = {
     { offsetof(TCCState, warn_unsupported), 0, "unsupported" },
     { offsetof(TCCState, warn_write_strings), 0, "write-strings" },
     { offsetof(TCCState, warn_error), 0, "error" },
-    { offsetof(TCCState, warn_implicit_function_declaration), WD_ALL,
-      "implicit-function-declaration" },
+    { offsetof(TCCState, warn_implicit_function_declaration), WD_ALL, "implicit-function-declaration" },
+    { offsetof(TCCState, warn_return_type), WD_ALL, "return-type" },
+    { offsetof(TCCState, warn_char_subscripts), WD_ALL, "char-subscripts" },
 };
 
 ST_FUNC int set_flag(TCCState *s, const FlagDef *flags, int nb_flags,
diff --git a/tcc.h b/tcc.h
index d0859d3..5cf639f 100644
--- a/tcc.h
+++ b/tcc.h
@@ -601,6 +601,8 @@ struct TCCState {
     int warn_error;
     int warn_none;
     int warn_implicit_function_declaration;
+    int warn_return_type;
+    int warn_char_subscripts;
 
     /* compile with debug symbol (and use them if error during execution) */
     int do_debug;
diff --git a/tccgen.c b/tccgen.c
index b2a7717..f134586 100644
--- a/tccgen.c
+++ b/tccgen.c
@@ -2927,13 +2927,12 @@ static void struct_decl(CType *type, int u, int tdef)
                     if (tok != ':') {
                         type_decl(&type1, &ad, &v, TYPE_DIRECT | TYPE_ABSTRACT);
                         if (v == 0 && (type1.t & VT_BTYPE) != VT_STRUCT)
-                            expect("identifier");
+                            expect("specifier-qualifier-list at end of input");
                         if (type_size(&type1, &align) < 0) {
-			    if ((a == TOK_STRUCT) && (type1.t & VT_ARRAY))
-			        flexible = 1;
-			    else
-			        tcc_error("field '%s' has incomplete type",
-                                      get_tok_str(v, NULL));
+                            if ((a == TOK_STRUCT) && (type1.t & VT_ARRAY))
+                                flexible = 1;
+                            else
+                                tcc_error("field '%s' has incomplete type", get_tok_str(v, NULL));
                         }
                         if ((type1.t & VT_BTYPE) == VT_FUNC ||
                             (type1.t & (VT_TYPEDEF | VT_STATIC | VT_EXTERN | VT_INLINE)))
@@ -2945,13 +2944,14 @@ static void struct_decl(CType *type, int u, int tdef)
                         bit_size = expr_const();
                         /* XXX: handle v = 0 case for messages */
                         if (bit_size < 0)
-                            tcc_error("negative width in bit-field '%s'", 
-                                  get_tok_str(v, NULL));
+                            tcc_error("negative width in bit-field '%s'", get_tok_str(v, NULL));
                         if (v && bit_size == 0)
-                            tcc_error("zero width for bit-field '%s'", 
-                                  get_tok_str(v, NULL));
+                            tcc_error("zero width for bit-field '%s'", get_tok_str(v, NULL));
                     }
-                    size = type_size(&type1, &align);
+                    if(type1.t & VT_VLA)
+                        size = 0, align = 1;
+                    else
+                        size = type_size(&type1, &align);
                     if (ad.a.aligned) {
                         if (align < ad.a.aligned)
                             align = ad.a.aligned;
@@ -3041,13 +3041,18 @@ static void struct_decl(CType *type, int u, int tdef)
                         *ps = ss;
                         ps = &ss->next;
                     }
-                    if (tok == ';' || tok == TOK_EOF)
+                    if (tok == ';' || tok == '}')
                         break;
-                    skip(',');
+                    if(tok == ',')
+                        next();
                 }
-                skip(';');
+                if(tok == '}'){
+                    tcc_warning("no ';' at end of struct or union");
+                    break;
+                }else
+                    skip(';');
             }
-            skip('}');
+            next();
             if (!c && flexible)
                 tcc_error("flexible array member '%s' in otherwise empty struct", get_tok_str(v, NULL));
             /* store size and alignment */
@@ -4061,6 +4066,8 @@ ST_FUNC void unary(void)
         } else if (tok == '[') {
             next();
             gexpr();
+            if(tcc_state->warn_char_subscripts && (vtop->type.t & (VT_BTYPE|VT_UNSIGNED)) == VT_BYTE)
+                tcc_warning("array subscript has type 'char'");
             gen_op('+');
             indir();
             skip(']');
@@ -5542,6 +5549,8 @@ static void decl_initializer_alloc(CType *type, AttributeDef *ad, int r,
 
     flexible_array = NULL;
     is_putz = 0;
+    if (has_init && (type->t & VT_VLA))
+        tcc_error("Variable length array cannot be initialized");
     if ((type->t & VT_BTYPE) == VT_STRUCT) {
         Sym *field = type->ref->next;
         if (field) {
@@ -5969,10 +5978,15 @@ static int decl0(int l, int is_for_loop_init)
                 break;
             btype.t = VT_INT;
         }
-        if (((btype.t & VT_BTYPE) == VT_ENUM ||
-             (btype.t & VT_BTYPE) == VT_STRUCT) && 
-            tok == ';') {
+        if (tok == ';') {
+            int bt = btype.t & VT_BTYPE;
             /* we accept no variable after */
+            if(btype.t & (VT_CONSTANT|VT_VOLATILE))
+                tcc_warning("useless type qualifier in empty declaration.'%s'before", get_tok_str(tok, NULL));
+            if(bt != VT_STRUCT && bt != VT_ENUM)
+                tcc_warning("useless type name in empty declaration '%s'", get_tok_str(tok, NULL));
+            if((bt == VT_STRUCT) && ((btype.ref->v & ~SYM_STRUCT) >= SYM_FIRST_ANOM))
+                tcc_warning("unnamed struct/union that defines no instances");
             next();
             continue;
         }
@@ -6143,8 +6157,6 @@ static int decl0(int l, int is_for_loop_init)
                         r |= lvalue_type(type.t);
                     }
                     has_init = (tok == '=');
-                    if (has_init && (type.t & VT_VLA))
-                        tcc_error("Variable length array cannot be initialized");
                     if ((btype.t & VT_EXTERN) || ((type.t & VT_BTYPE) == VT_FUNC) ||
                         ((type.t & VT_ARRAY) && (type.t & VT_STATIC) &&
                          !has_init && l == VT_CONST && type.ref->c < 0)) {