duplicate member

Check duplicate struct/union member names

tcc.h: Add cnt field in TokenSym

tccgen.c: New function check_fields to find duplicate member names.

This avoids quadratic behavior and can be used for large structs.

tcc.h

@@ -432,6 +432,7 @@ typedef struct TokenSym {
     struct Sym *sym_struct; /* direct pointer to structure */
     struct Sym *sym_identifier; /* direct pointer to identifier */
     int tok; /* token number */
+    int cnt;
     int len;
     char str[1];
 } TokenSym;

tccgen.c

@@ -4321,6 +4321,41 @@ static Sym * find_field (CType *type, int v, int *cumofs)
     return s;
 }
 
+/*
+ * c = 0: reset symbol counter
+ * c = 1: increment symbol counter
+ * c = 2: check symbol counter
+ */
+
+static void check_fields (CType *type, int c)
+{
+    Sym *s = type->ref;
+    int v;
+
+    while ((s = s->next) != NULL) {
+	if ((s->v & SYM_FIELD) &&
+	    (s->type.t & VT_BTYPE) == VT_STRUCT &&
+	    (s->v & ~SYM_FIELD) >= SYM_FIRST_ANOM) {
+	    check_fields (&s->type, c);
+	}
+	v = s->v & ~SYM_FIELD;
+	if (v < tok_ident)
+	    switch (c) {
+	    case 0:
+		table_ident[v - TOK_IDENT]->cnt = 0;
+		break;
+	    case 1:
+		table_ident[v - TOK_IDENT]->cnt++;
+		break;
+	    case 2:
+		if (table_ident[v - TOK_IDENT]->cnt != 1)
+		    tcc_error("duplicate member '%s'",
+			      get_tok_str(v, NULL));
+	        break;
+	}
+    }
+}
+
 static void struct_layout(CType *type, AttributeDef *ad)
 {
     int size, align, maxalign, offset, c, bit_pos, bit_size;
@@ -4774,6 +4809,9 @@ do_decl:
             if (ad.cleanup_func) {
                 tcc_warning("attribute '__cleanup__' ignored on type");
             }
+	    check_fields(type, 0);
+	    check_fields(type, 1);
+	    check_fields(type, 2);
             struct_layout(type, &ad);
         }
     }

tests/tests2/60_errors_and_warnings.c

@@ -366,4 +366,21 @@ n[sizeof({3;})]; // crashed in block() due to missing local scope
 f(){"12"3;} // second const token killed the value of the first
 
 /******************************************************************/
+#elif defined test_duplicate_member
+struct S {
+  int a, a;
+};
+#elif defined test_duplicate_member_anon
+struct S1 {
+  int b;
+  struct {
+    int b;
+  } c;
+};
+struct S2 {
+  int d;
+  struct {
+    int d;
+  };
+};
 #endif

tests/tests2/60_errors_and_warnings.expect

@@ -174,3 +174,9 @@ bar  : 3 ; 3
 
 [test_invalid_tokckill]
 60_errors_and_warnings.c:366: error: ';' expected (got "3")
+
+[test_duplicate_member]
+60_errors_and_warnings.c:372: error: duplicate member 'a'
+
+[test_duplicate_member_anon]
+60_errors_and_warnings.c:385: error: duplicate member 'd'