an attempt to improve error correction on unknown type identifiers.

Also, a minor fix to ival.g

lang/cem/cemcom/declar.g

@@ -68,7 +68,8 @@ decl_specifiers	/* non-empty */ (register struct decspecs *ds;)
 :
 [
 	other_specifier(ds)+
-	[%prefer /* the thin ice in R.M. 11.1 */
+	[%if (DOT != IDENTIFIER || AHEAD == IDENTIFIER)
+		/* the thin ice in R.M. 11.1 */
 		single_type_specifier(ds) other_specifier(ds)*
 	|
 		empty
@@ -121,6 +122,11 @@ type_specifier(struct type **tpp;)
 single_type_specifier(register struct decspecs *ds;):
 	TYPE_IDENTIFIER		/* this includes INT, CHAR, etc. */
 	{idf2type(dot.tk_idf, &ds->ds_type);}
+|
+	IDENTIFIER
+	{error("%s is not a type identifier", dot.tk_idf->id_text);
+	 ds->ds_type = error_type;
+	}
 |
 	struct_or_union_specifier(&ds->ds_type)
 |

lang/cem/cemcom/expression.g

@@ -96,7 +96,7 @@ postfixed(struct expr **expp;)
 unary(register struct expr **expp;)
 	{struct type *tp; int oper;}
 :
-%if (first_of_type_specifier(AHEAD))
+%if (first_of_type_specifier(AHEAD) && AHEAD != IDENTIFIER)
 	cast(&tp) unary(expp)
 	{	ch7cast(expp, CAST, tp);
 		(*expp)->ex_flags |= EX_CAST;
@@ -114,7 +114,7 @@ size_of(register struct expr **expp;)
 	{struct type *tp;}
 :
 	SIZEOF
-	[%if (first_of_type_specifier(AHEAD))
+	[%if (first_of_type_specifier(AHEAD) && AHEAD != IDENTIFIER)
 		cast(&tp)
 		{
 			*expp = intexpr(size_of_type(tp, "type"), INT);

lang/cem/cemcom/ival.g

@@ -193,6 +193,10 @@ gen_tphead(tpp, nest)
 	register struct e_stack *p;
 	register struct sdef *sd;
 
+	if (tpp && *tpp == error_type) {
+		gen_error = 1;
+		return 0;
+	}
 	if (gen_error) return tpp;
 	p = new_e_stack();
 	p->next = p_stack;
@@ -217,6 +221,13 @@ gen_tphead(tpp, nest)
 			sd = next_field(sd, p);
 		}
 #endif
+		if (! sd) {
+			/* something wrong with this struct */
+			gen_error = 1;
+			p_stack = p->next;
+			free_e_stack(p);
+			return 0;
+		}
 		p->s_def = sd;
 		if (AHEAD != '{' && aggregate_type(sd->sd_type)) {
 			return gen_tphead(&(sd->sd_type), 1);
@@ -236,7 +247,10 @@ gen_tpmiddle()
 	register struct sdef *sd;
 	register struct e_stack *p = p_stack;
 
-	if (gen_error) if (p) return p->s_tpp; else return 0;
+	if (gen_error) {
+		if (p) return p->s_tpp;
+		return 0;
+	}
 again:
 	tp = *(p->s_tpp);
 	switch(tp->tp_fund) {

lang/cem/cemcom/program.g

@@ -140,7 +140,7 @@ external_definition
 ;
 
 ext_decl_specifiers(struct decspecs *ds;) :
-%prefer /* the thin ice in  R.M. 11.1 */
+%if (DOT != IDENTIFIER || AHEAD == IDENTIFIER) /* the thin ice in  R.M. 11.1 */
 	decl_specifiers(ds)
 |
 	empty

lang/cem/cemcom/statement.g

@@ -358,7 +358,9 @@ compound_statement:
 		{
 			stack_level();
 		}
-	[%while (AHEAD != ':')		/* >>> conflict on TYPE_IDENTIFIER */
+	[%while ((DOT != IDENTIFIER && AHEAD != ':') ||
+		 (DOT == IDENTIFIER && AHEAD == IDENTIFIER))
+			/* >>> conflict on TYPE_IDENTIFIER, IDENTIFIER */
 		declaration
 	]*
 	[%persistent