Elab bitfields: check size of type <=32bit rather than checking rank (#387)

When desugaring a bitfield, allow any integral type that is 32 bits
or smaller. Previously this was checking the rank of the type rather
than the size.

This rank check caused issues with standard headers that
declare `uint32_t` to be an `unsigned long` rather than an
`unsigned int`. Here, any bitfields declared as `uint32_t` were
failing to compile even though they are still actually 32 bits.

Co-authored-by: Amos Robinson <amos@gh.st>

1 files changed, 22 insertions, 0 deletions

diff --git a/test/regression/bitfields_uint_t.c b/test/regression/bitfields_uint_t.c
new file mode 100644
index 00000000..3d7fb4e7
--- /dev/null
+++ b/test/regression/bitfields_uint_t.c
@@ -0,0 +1,22 @@
+#include <stdio.h>
+#include <stdint.h>
+
+/* Test that uint32 type synonym works.
+   This previously failed for standard headers where uint32 is defined
+   as a (32-bit) unsigned long. */
+
+struct s {
+  uint32_t a: 1;
+  uint32_t b: 2;
+  uint32_t c: 9;
+  uint32_t d: 20;
+};
+
+struct s x = { 1, 2, 3, 4 };
+
+int main()
+{
+  printf("x = { a = %d, b = %d, c = %d, d = %d }\n", x.a, x.b, x.c, x.d);
+}
+
+