X-Git-Url: https://git.draconx.ca/gitweb/cdecl99.git/blobdiff_plain/ccab8e9fa4419c944f831612d5b5474c847485fa..eda9528293fbc32857a5856a30ebd6585b281215:/src/parse.y

diff --git a/src/parse.y b/src/parse.y
index 9e54761..14d593e 100644
--- a/src/parse.y
+++ b/src/parse.y
@@ -41,46 +41,67 @@
 	YYERROR; \
 } while (0)
 
-#define ALLOC(ptr, size) do { \
-	(ptr) = malloc(size); \
-	if (!(ptr)) { \
-		cdecl__errmsg(CDECL__ENOMEM); \
+/*
+ * Allocate a parse tree node via cdecl__alloc_item.
+ *
+ * - m1 specifies the item's union member to assign to ptr, which selects the
+ *   type of node to allocate.
+ *
+ * - m2 specifies the "next" or "child" member, which is initialized to a null
+ *   pointer.  The cdecl__alloc_item function sets the declarator.child member
+ *   to null; we explicitly copy this null pointer to the returned union member
+ *   to avoid type punning.  It is hoped that compilers will notice that these
+ *   pointers are at the same offset therefore the assignment can be elided.
+ *
+ * The resulting pointer can be passed directly to free, as the union is the
+ * first member of the parse_item structure.
+ *
+ * Use the wrapper macros below instead of this one.
+ */
+#define ALLOC_ITEM(ptr, m1, m2) do { \
+	struct parse_item *item; \
+	if (!(item = cdecl__alloc_item(0))) \
 		YYERROR; \
-	} \
+	item->u.m1.m2 = (void *)item->u.declarator.child; \
+	(ptr) = &item->u.m1; \
 } while (0)
 
+/* Wrappers for ALLOC_ITEM to allocate various kinds of parser structures. */
+#define ALLOC_ITEM_DECLARATOR(ptr) ALLOC_ITEM(ptr, declarator, child)
+#define ALLOC_ITEM_DECLSPEC(ptr)   ALLOC_ITEM(ptr, declspec, next)
+#define ALLOC_ITEM_DECL(ptr)       ALLOC_ITEM(ptr, decl, next)
+
 #define ALLOC_FUNCTION(ptr, parameters_, variadic_) do { \
-	ALLOC(ptr, sizeof (struct cdecl_declarator)); \
+	ALLOC_ITEM_DECLARATOR(ptr); \
 	(ptr)->type = CDECL_DECL_FUNCTION; \
 	(ptr)->u.function.parameters = parameters_; \
 	(ptr)->u.function.variadic = variadic_; \
 } while (0)
 
 #define ALLOC_ARRAY(ptr, length_) do { \
-	ALLOC(ptr, sizeof (struct cdecl_declarator)); \
+	ALLOC_ITEM_DECLARATOR(ptr); \
 	(ptr)->type = CDECL_DECL_ARRAY; \
 	(ptr)->u.array.vla = NULL; \
 	(ptr)->u.array.length = length_; \
 } while (0)
 
 #define ALLOC_POINTER(ptr, qualifiers_, child_) do { \
-	ALLOC(ptr, sizeof (struct cdecl_declarator)); \
+	ALLOC_ITEM_DECLARATOR(ptr); \
 	(ptr)->child = child_; \
 	(ptr)->type = CDECL_DECL_POINTER; \
 	(ptr)->u.pointer.qualifiers = qualifiers_; \
 } while (0)
 
 #define ALLOC_DECLSPEC(ptr, type_) do { \
-	ALLOC(ptr, sizeof (struct cdecl_declspec)); \
+	ALLOC_ITEM_DECLSPEC(ptr); \
 	(ptr)->type = type_; \
 	(ptr)->ident = NULL; \
 } while (0)
 
 #define ALLOC_DECL(ptr, specifiers_, declarators_) do { \
-	ALLOC(ptr, sizeof (struct cdecl)); \
+	ALLOC_ITEM_DECL(ptr); \
 	(ptr)->specifiers = specifiers_; \
 	(ptr)->declarators = declarators_; \
-       (ptr)->next = NULL; \
 } while (0)
 
 /*
@@ -88,7 +109,13 @@
  * name strings can be used directly in error messages and there is no
  * need for any string processing.
  */
-#define yytnamerr(a, b) cdecl__strlcpy(a, b, (a) ? INT_MAX : 0)
+#define yytnamerr(a, b) ( (a) ? yytnamerr_copy(a, b) \
+                              : strlen(b) )
+
+static size_t yytnamerr_copy(char *dst, const char *src)
+{
+	return cdecl__strlcpy(dst, src, strlen(src)+1);
+}
 %}
 
 %code requires {