ffi: pack bugfix and tests.

* ffi.c (ffi_transform_pack): Fix: return the original syntax in
the situation when no cases are recognized, rather than
the cdr of the syntax. When the struct/union syntax has no
members, return the original syntax to indicate no transformation
took place.

* txr.1: Document the feature that pack on a typedef name or struct
name with no members will do the alignment adjustment only, without
the syntactic transformation.

* tests/017/pack-align.tl: New file.

1 files changed, 112 insertions, 0 deletions

diff --git a/tests/017/pack-align.tl b/tests/017/pack-align.tl
new file mode 100644
index 00000000..a1048788
--- /dev/null
+++ b/tests/017/pack-align.tl
@@ -0,0 +1,112 @@
+(load "../common")
+
+(mtest
+  (alignof int) 4
+  (alignof (align int)) 16
+  (alignof (align 1 int)) 4
+  (alignof (align 6 int)) :error
+  (alignof (align 8 int)) 8)
+
+(mtest
+  (alignof (pack int)) 1
+  (alignof (pack 1 int)) 1
+  (alignof (pack 6 int)) :error
+  (alignof (pack 8 int)) 8)
+
+(mtest
+  (alignof (pack 1 (align 8 int))) 8
+  (alignof (align 8 (pack 1 int))) 8)
+
+(typedef s0 (pack (struct s0
+                    (a char)
+                    (b short)
+                    (c int)
+                    (d longlong))))
+
+(mtest
+  (alignof s0.a) 1
+  (alignof s0.b) 1
+  (alignof s0.c) 1
+  (alignof s0.d) 1)
+
+(mtest
+  (offsetof s0 a) 0
+  (offsetof s0 b) 1
+  (offsetof s0 c) 3
+  (offsetof s0 d) 7
+  (sizeof s0) 15)
+
+(typedef s1 (pack 2 (struct s1
+                      (a char)
+                      (b short)
+                      (c int)
+                      (d longlong))))
+
+(mtest
+  (alignof s1.a) 2
+  (alignof s1.b) 2
+  (alignof s1.c) 2
+  (alignof s1.d) 2)
+
+(mtest
+  (offsetof s1 a) 0
+  (offsetof s1 b) 2
+  (offsetof s1 c) 4
+  (offsetof s1 d) 8
+  (sizeof s1) 16)
+
+(typedef s2 (pack 32 (struct s2
+                       (a char)
+                       (b short)
+                       (c int)
+                       (d longlong))))
+
+(mtest
+  (alignof s2.a) 32
+  (alignof s2.b) 32
+  (alignof s2.c) 32
+  (alignof s2.d) 32)
+
+(mtest
+  (offsetof s2 a) 0
+  (offsetof s2 b) 32
+  (offsetof s2 c) 64
+  (offsetof s2 d) 96
+  (sizeof s2) 128)
+
+(typedef s3 (pack 1 (struct s3
+                      (a char)
+                      (b (align 2 char))
+                      (c (align int))
+                      (d longlong))))
+
+(mtest
+  (alignof s3.a) 1
+  (alignof s3.b) 2
+  (alignof s3.c) 16
+  (alignof s3.d) 1)
+
+(mtest
+  (offsetof s3 a) 0
+  (offsetof s3 b) 2
+  (offsetof s3 c) 16
+  (offsetof s3 d) 20
+  (sizeof s3) 32)
+
+(typedef s4 (align 256 s3))
+
+(mtest
+  (sizeof s4) 32
+  (alignof s4) 256)
+
+(typedef s5 (pack s3))
+
+(mtest
+  (sizeof s5) 32
+  (alignof s5) 1)
+
+(typedef s6 (pack (struct s3)))
+
+(mtest
+  (sizeof s6) 32
+  (alignof s6) 1)