From 941b006002df94fa41d413d01cc55f15a8ecbd31 Mon Sep 17 00:00:00 2001
From: Nick Bowler <nbowler@draconx.ca>
Date: Wed, 6 Jul 2011 22:31:48 -0400
Subject: [PATCH] Validate function return types.

---
 src/parse-decl.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/src/parse-decl.c b/src/parse-decl.c
index dd4bd19..059f5f7 100644
--- a/src/parse-decl.c
+++ b/src/parse-decl.c
@@ -275,6 +275,10 @@ reduce_parentheses(struct cdecl_declarator **p, struct cdecl_declarator *d)
 	return 0;
 }
 
+/*
+ * Function parameters and return types have a few restrictions that are
+ * really easy to check in comparison to the above absurdity.
+ */
 static int
 check_parameters(struct cdecl_declarator **p, struct cdecl_declarator *d)
 {
@@ -307,6 +311,28 @@ check_parameters(struct cdecl_declarator **p, struct cdecl_declarator *d)
 	return 0;
 }
 
+/*
+ * Functions cannot return arrays or functions.  Since the parse tree is
+ * "inside-out", we need to look for functions as the child declarator.
+ */
+static int
+check_rettypes(struct cdecl_declarator **p, struct cdecl_declarator *d)
+{
+	if (!d->child || d->child->type != CDECL_DECL_FUNCTION)
+		return 0;
+
+	switch (d->type) {
+	case CDECL_DECL_FUNCTION:
+		fprintf(stderr, "functions cannot return functions\n");
+		return -1;
+	case CDECL_DECL_ARRAY:
+		fprintf(stderr, "functions cannot return arrays\n");
+		return -1;
+	}
+
+	return 0;
+}
+
 /*
  * Traverse the parse tree, calling a function on every declarator in a
  * depth-first preorder traversal.  The function is given a pointer to the
@@ -364,6 +390,8 @@ struct cdecl *cdecl_parse_decl(const char *declstr)
 			goto err;
 		if (!forall_declarators(i, check_parameters))
 			goto err;
+		if (!forall_declarators(i, check_rettypes))
+			goto err;
 
 		if (!valid_declspecs(i, true))
 			goto err;
-- 
2.43.2