various null-dereference problems fixed

lang/cem/cemcom/code.c

@@ -183,7 +183,12 @@ begin_proc(name, def)	/* to be called when entering a procedure	*/
 		DfaStartFunction(name);
 #endif	DATAFLOW
 
-	func_tp = def->df_type->tp_up;
+	if (def->df_type->tp_fund != FUNCTION) {
+		error("making function body for non-function");
+		func_tp = error_type;
+	}
+	else
+		func_tp = def->df_type->tp_up;
 	size = ATW(func_tp->tp_size);
 	C_pro_narg(name);
 	if (is_struct_or_union(func_tp->tp_fund))	{

lang/cem/cemcom/expr.c

@@ -171,6 +171,7 @@ idf2expr(expr)
 	/* now def != 0 */
 	if (def->df_type->tp_fund == LABEL) {
 		expr_error(expr, "illegal use of label %s", idf->id_text);
+		expr->ex_type = error_type;
 	}
 	else {
 		def->df_used = 1;

lang/cem/cemcom/idf.c

@@ -181,7 +181,7 @@ declare_idf(ds, dc, lvl)
 		/*	at the L_FORMAL1 level there is no type specified yet
 		*/
 		ASSERT(lvl == L_FORMAL1);
-		type = 0;
+		type = int_type;	/* may change at L_FORMAL2 */
 	}
 	else	{
 		/* combine the decspecs and the declarator into one type */
@@ -583,7 +583,7 @@ declare_parameter(idf)
 {
 	/*	idf is declared as a formal.
 	*/
-	add_def(idf, FORMAL, (struct type *)0, level);
+	add_def(idf, FORMAL, int_type, level);
 }
 
 declare_enum(tp, idf, l)
@@ -616,8 +616,6 @@ declare_formals(fp)
 		struct idf *idf = se->se_idf;
 		struct def *def = idf->id_def;
 		
-		if (def->df_type == 0)
-			def->df_type = int_type; /* default type */
 		def->df_address = f_offset;
 
 		/*	the alignment convention for parameters is: align on

lang/cem/cemcom/statement.g

@@ -279,7 +279,7 @@ switch_statement
 	'('
 	expression(&expr)
 		{
-			code_startswitch(expr);
+			code_startswitch(&expr);
 		}
 	')'
 	statement

lang/cem/cemcom/struct.c

@@ -310,7 +310,7 @@ idf2sdef(idf, tp)
 	*sdefp = sdef = new_sdef();
 	clear((char *)sdef, sizeof(struct sdef));
 	sdef->sd_idf = idf;
-	sdef->sd_type = error_type;
+	sdef->sd_stype = sdef->sd_type = error_type;
 	return sdef;
 }
 

lang/cem/cemcom/switch.c

@@ -32,8 +32,8 @@ static struct switch_hdr *switch_stack = 0;
 	For simplicity, we suppose int_size == word_size.
 */
 
-code_startswitch(expr)
-	struct expr *expr;
+code_startswitch(expp)
+	struct expr **expp;
 {
 	/*	Check the expression, stack a new case header and
 		fill in the necessary fields.
@@ -41,17 +41,17 @@ code_startswitch(expr)
 	register label l_table = text_label();
 	register label l_break = text_label();
 	register struct switch_hdr *sh = new_switch_hdr();
-	int fund = any2arith(&expr, SWITCH);	/* INT, LONG or DOUBLE */
+	int fund = any2arith(expp, SWITCH);	/* INT, LONG or DOUBLE */
 	
 	switch (fund)	{
 	case LONG:
 		if (options['R'])
 			warning("long in switch (cast to int)");
-		int2int(&expr, int_type);
+		int2int(expp, int_type);
 		break;
 	case DOUBLE:
 		error("float/double in switch");
-		erroneous2int(&expr);
+		erroneous2int(expp);
 		break;
 	}
 	
@@ -60,12 +60,12 @@ code_startswitch(expr)
 	sh->sh_default = 0;
 	sh->sh_table = l_table;
 	sh->sh_nrofentries = 0;
-	sh->sh_type = expr->ex_type;	/* the expression switched	*/
+	sh->sh_type = (*expp)->ex_type;	/* the expression switched	*/
 	sh->sh_lowerbd = sh->sh_upperbd = (arith)0;	/* immaterial ??? */
 	sh->sh_entries = (struct case_entry *) 0; /* case-entry list	*/
 	sh->next = switch_stack;	/* push onto switch-stack	*/
 	switch_stack = sh;
-	code_expr(expr, RVAL, TRUE, NO_LABEL, NO_LABEL);
+	code_expr(*expp, RVAL, TRUE, NO_LABEL, NO_LABEL);
 					/* evaluate the switch expr.	*/
 	C_bra(l_table);			/* goto start of switch_table	*/
 }