Merge branch 'bitwise-ptr'

* warn on casts to/from bitwise pointers

6 files changed, 67 insertions, 0 deletions

diff --git a/evaluate.c b/evaluate.c
index 64c02564..4c8c002e 100644
--- a/evaluate.c
+++ b/evaluate.c
@@ -3045,6 +3045,25 @@ static struct symbol *evaluate_cast(struct expression *expr)
 	if (ttype == &bool_ctype)
 		cast_to_bool(expr);
 
+	// checks pointers to restricted
+	while (Wbitwise_pointer && tclass == TYPE_PTR && sclass == TYPE_PTR) {
+		tclass = classify_type(ttype->ctype.base_type, &ttype);
+		sclass = classify_type(stype->ctype.base_type, &stype);
+		if (ttype == stype)
+			break;
+		if (!ttype || !stype)
+			break;
+		if (ttype == &void_ctype || stype == &void_ctype)
+			break;
+		if (tclass & TYPE_RESTRICT) {
+			warning(expr->pos, "cast to %s", show_typename(ctype));
+			break;
+		}
+		if (sclass & TYPE_RESTRICT) {
+			warning(expr->pos, "cast from %s", show_typename(source->ctype));
+			break;
+		}
+	}
 out:
 	return ctype;
 }
diff --git a/lib.c b/lib.c
index 9f8213df..7bf66cd0 100644
--- a/lib.c
+++ b/lib.c
@@ -253,6 +253,7 @@ static struct token *pre_buffer_end = NULL;
 int Waddress = 0;
 int Waddress_space = 1;
 int Wbitwise = 1;
+int Wbitwise_pointer = 0;
 int Wcast_from_as = 0;
 int Wcast_to_as = 0;
 int Wcast_truncate = 1;
@@ -684,6 +685,7 @@ static const struct flag warnings[] = {
 	{ "address", &Waddress },
 	{ "address-space", &Waddress_space },
 	{ "bitwise", &Wbitwise },
+	{ "bitwise-pointer", &Wbitwise_pointer},
 	{ "cast-from-as", &Wcast_from_as },
 	{ "cast-to-as", &Wcast_to_as },
 	{ "cast-truncate", &Wcast_truncate },
diff --git a/lib.h b/lib.h
index f2f5f839..322408be 100644
--- a/lib.h
+++ b/lib.h
@@ -139,6 +139,7 @@ extern int preprocess_only;
 extern int Waddress;
 extern int Waddress_space;
 extern int Wbitwise;
+extern int Wbitwise_pointer;
 extern int Wcast_from_as;
 extern int Wcast_to_as;
 extern int Wcast_truncate;
diff --git a/sparse.1 b/sparse.1
index ccee2808..096c5b08 100644
--- a/sparse.1
+++ b/sparse.1
@@ -77,6 +77,12 @@ Sparse issues these warnings by default.  To turn them off, use
 \fB\-Wno\-bitwise\fR.
 .
 .TP
+.B \-Wbitwise\-pointer
+Same as \fB\-Wbitwise\fR but for casts to or from pointers to bitwise types.
+
+Sparse does not issue these warnings by default.
+.
+.TP
 .B \-Wcast\-from\-as
 Warn about which remove an address space to a pointer type.
 
diff --git a/validation/bitwise-cast-ptr.c b/validation/bitwise-cast-ptr.c
new file mode 100644
index 00000000..3f2bfdaf
--- /dev/null
+++ b/validation/bitwise-cast-ptr.c
@@ -0,0 +1,33 @@
+#define __bitwise	__attribute__((bitwise))
+#define __force		__attribute__((force))
+
+typedef unsigned int u32;
+typedef unsigned int __bitwise __be32;
+
+static __be32* tobi(u32 *x)
+{
+	return x;			// should warn, implicit cast
+}
+
+static __be32* tobe(u32 *x)
+{
+	return (__be32 *) x;		// should warn, explicit cast
+}
+
+static __be32* tobf(u32 *x)
+{
+	return (__force __be32 *) x;	// should not warn, forced cast
+	return (__be32 __force *) x;	// should not warn, forced cast
+}
+
+/*
+ * check-name: cast of bitwise pointers
+ * check-command: sparse -Wbitwise -Wbitwise-pointer $file
+ *
+ * check-error-start
+bitwise-cast-ptr.c:9:16: warning: incorrect type in return expression (different base types)
+bitwise-cast-ptr.c:9:16:    expected restricted __be32 [usertype] *
+bitwise-cast-ptr.c:9:16:    got unsigned int [usertype] *x
+bitwise-cast-ptr.c:14:17: warning: cast to restricted __be32 [usertype] *<noident>
+ * check-error-end
+ */
diff --git a/validation/bitwise-cast.c b/validation/bitwise-cast.c
index baeca29e..0583461c 100644
--- a/validation/bitwise-cast.c
+++ b/validation/bitwise-cast.c
@@ -29,6 +29,12 @@ static __be32 quux(void)
 	return (__be32)1729;
 }
 
+/* Explicit case of nonzero forced, legal */
+static __be32 quuy(void)
+{
+	return (__attribute__((force)) __be32) 1730;
+}
+
 /*
  * check-name: conversions to bitwise types
  * check-command: sparse -Wbitwise $file