Auto merge of #413 - emilio:debug-array-unaligned, r=fitzgen

codegen: Avoid generating invalid Rust code when a struct is not properly aligned.

r? @fitzgen

cc #412

1 files changed, 13 insertions, 11 deletions

diff --git a/libbindgen/src/codegen/helpers.rs b/libbindgen/src/codegen/helpers.rs
index b4cc75f5..06dadab0 100644
--- a/libbindgen/src/codegen/helpers.rs
+++ b/libbindgen/src/codegen/helpers.rs
@@ -49,20 +49,22 @@ impl BlobTyBuilder {
     }
 
     pub fn build(self) -> P<ast::Ty> {
-        use std::cmp;
+        let opaque = self.layout.opaque();
 
-        let ty_name = match self.layout.align {
-            8 => "u64",
-            4 => "u32",
-            2 => "u16",
-            1 | _ => "u8",
-        };
-        let data_len = if ty_name == "u8" {
-            self.layout.size
-        } else {
-            self.layout.size / cmp::max(self.layout.align, 1)
+        // FIXME(emilio, #412): We fall back to byte alignment, but there are
+        // some things that legitimately are more than 8-byte aligned.
+        //
+        // Eventually we should be able to `unwrap` here, but...
+        let ty_name = match opaque.known_rust_type_for_array() {
+            Some(ty) => ty,
+            None => {
+                warn!("Found unknown alignment on code generation!");
+                "u8"
+            }
         };
 
+        let data_len = opaque.array_size().unwrap_or(self.layout.size);
+
         let inner_ty = aster::AstBuilder::new().ty().path().id(ty_name).build();
         if data_len == 1 {
             inner_ty