struct_layout: Fix field offset computation for packed(n) structs.

This can cause unnecessary padding to be computed otherwise at the end
of the struct.

With repr(packed(n)), a field can have padding to adjacent fields as
long as its alignment is less than n. So reuse the code we have to align
to a field layout, aligning to the struct layout instead.

Fixes #1934

1 files changed, 8 insertions, 0 deletions

diff --git a/tests/headers/packed-n-with-padding.h b/tests/headers/packed-n-with-padding.h
new file mode 100644
index 00000000..8a6233b5
--- /dev/null
+++ b/tests/headers/packed-n-with-padding.h
@@ -0,0 +1,8 @@
+#pragma pack(push, 2)
+struct Packed {
+    char a;
+    short b;
+    char c;
+    int d;
+};
+#pragma pack(pop)