fix eval of the assignment of a non-restricted value to a restricted variable

Commit Message

Luc Van Oostenryck Feb. 25, 2021, 10:05 p.m. UTC

Assignment to restricted variables are severely ... restricted.
Nevertheless, one value is always fine because it has always
the same bit representation: 0.

So, 0 is accepted unconditionally but this creates a problem
because the type of this 0 needs to be adjusted. Otherwise
0 (int) is assigned as-is even on restricted variable with a
different bit-length.

Fix this by casting the value to the target type before accepting it.

Signed-off-by: Luc Van Oostenryck <[e-mail]>
---
 evaluate.c                             |  2 +-
 validation/eval/assign-restricted-ok.c | 22 ++++++++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)
 create mode 100644 validation/eval/assign-restricted-ok.c

Patch

diff --git a/evaluate.c b/evaluate.c
index 41871e18503a..a661027f8df6 100644
--- a/evaluate.c
+++ b/evaluate.c
@@ -1442,7 +1442,7 @@  static int check_assignment_types(struct symbol *target, struct expression **rp,
 			if (sclass & TYPE_FOULED && unfoul(s) == t)
 				goto Cast;
 			if (!restricted_value(*rp, target))
-				return 1;
+				goto Cast;
 			if (s == t)
 				return 1;
 		} else if (!(sclass & TYPE_RESTRICT))
diff --git a/validation/eval/assign-restricted-ok.c b/validation/eval/assign-restricted-ok.c
new file mode 100644
index 000000000000..df94d8c9d6d0
--- /dev/null
+++ b/validation/eval/assign-restricted-ok.c
@@ -0,0 +1,22 @@ 
+#ifdef __CHECKER__
+#define __bitwise __attribute__((bitwise))
+#else
+#define __bitwise
+#endif
+
+typedef __INT16_TYPE__ __bitwise __be16;
+
+static __be16 foo(void)
+{
+	__be16 val = 0;
+	return val;
+}
+
+/*
+ * check-name: assign-restricted-ok
+ * check-command: test-linearize -fdump-ir $file
+ *
+ * check-output-ignore
+ * check-output-contains: store\\.16
+ * check-output-excludes: store\\.32
+ */