Simplify helpers::blob

Thanks @fitzgen for the detailed instructions.
Fixes #928.

Author: MaloJaffre

src/codegen/helpers.rs

@@ -60,40 +60,28 @@ pub mod attributes {
 
 /// Generates a proper type for a field or type with a given `Layout`, that is,
 /// a type with the correct size and alignment restrictions.
-pub struct BlobTyBuilder {
-    layout: Layout,
-}
-
-impl BlobTyBuilder {
-    pub fn new(layout: Layout) -> Self {
-        BlobTyBuilder {
-            layout: layout,
+pub fn blob(layout: Layout) -> P<ast::Ty> {
+    let opaque = layout.opaque();
+
+    // 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"
         }
-    }
+    };
 
-    pub fn build(self) -> P<ast::Ty> {
-        let opaque = self.layout.opaque();
+    let data_len = opaque.array_size().unwrap_or(layout.size);
 
-        // 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
-        } else {
-            aster::ty::TyBuilder::new().array(data_len).build(inner_ty)
-        }
+    let inner_ty = aster::AstBuilder::new().ty().path().id(ty_name).build();
+    if data_len == 1 {
+        inner_ty
+    } else {
+        aster::ty::TyBuilder::new().array(data_len).build(inner_ty)
     }
 }
 

src/codegen/mod.rs

@@ -3,7 +3,7 @@ mod error;
 mod helpers;
 pub mod struct_layout;
 
-use self::helpers::{BlobTyBuilder, attributes};
+use self::helpers::attributes;
 use self::struct_layout::StructLayoutTracker;
 
 use aster;
@@ -1155,7 +1155,7 @@ impl Bitfield {
         let bitfield_ty_layout = bitfield_ty.layout(ctx).expect(
             "Bitfield without layout? Gah!",
         );
-        let bitfield_int_ty = BlobTyBuilder::new(bitfield_ty_layout).build();
+        let bitfield_int_ty = helpers::blob(bitfield_ty_layout);
         let bitfield_ty =
             bitfield_ty.to_rust_ty_or_opaque(ctx, bitfield_ty_item);
 
@@ -1205,7 +1205,7 @@ impl<'a> FieldCodegen<'a> for BitfieldUnit {
         F: Extend<ast::StructField>,
         M: Extend<ast::ImplItem>,
     {
-        let field_ty = BlobTyBuilder::new(self.layout()).build();
+        let field_ty = helpers::blob(self.layout());
         let unit_field_name = format!("_bitfield_{}", self.nth());
 
         let field = StructFieldBuilder::named(&unit_field_name)
@@ -1355,7 +1355,7 @@ impl<'a> FieldCodegen<'a> for Bitfield {
         let bitfield_ty_layout = bitfield_ty.layout(ctx).expect(
             "Bitfield without layout? Gah!",
         );
-        let bitfield_int_ty = BlobTyBuilder::new(bitfield_ty_layout).build();
+        let bitfield_int_ty = helpers::blob(bitfield_ty_layout);
 
         let bitfield_ty =
             bitfield_ty.to_rust_ty_or_opaque(ctx, bitfield_ty_item);
@@ -1639,7 +1639,7 @@ impl CodeGenerator for CompInfo {
 
         if is_union {
             let layout = layout.expect("Unable to get layout information?");
-            let ty = BlobTyBuilder::new(layout).build();
+            let ty = helpers::blob(layout);
 
             let field = if self.can_be_rust_union(ctx) {
                 StructFieldBuilder::named("_bindgen_union_align").build_ty(ty)
@@ -1662,7 +1662,7 @@ impl CodeGenerator for CompInfo {
 
             match layout {
                 Some(l) => {
-                    let ty = BlobTyBuilder::new(l).build();
+                    let ty = helpers::blob(l);
                     let field = StructFieldBuilder::named(
                         "_bindgen_opaque_blob",
                     ).pub_()
@@ -1707,7 +1707,7 @@ impl CodeGenerator for CompInfo {
             };
 
             if has_address {
-                let ty = BlobTyBuilder::new(Layout::new(1, 1)).build();
+                let ty = helpers::blob(Layout::new(1, 1));
                 let field =
                     StructFieldBuilder::named("_address").pub_().build_ty(ty);
                 fields.push(field);
@@ -2728,7 +2728,7 @@ trait TryToOpaque {
         extra: &Self::Extra,
     ) -> error::Result<P<ast::Ty>> {
         self.try_get_layout(ctx, extra).map(|layout| {
-            BlobTyBuilder::new(layout).build()
+            helpers::blob(layout)
         })
     }
 }
@@ -2756,7 +2756,7 @@ trait ToOpaque: TryToOpaque {
         extra: &Self::Extra,
     ) -> P<ast::Ty> {
         let layout = self.get_layout(ctx, extra);
-        BlobTyBuilder::new(layout).build()
+        helpers::blob(layout)
     }
 }
 
@@ -2814,7 +2814,7 @@ where
             |_| if let Ok(layout) =
                 self.try_get_layout(ctx, extra)
             {
-                Ok(BlobTyBuilder::new(layout).build())
+                Ok(helpers::blob(layout))
             } else {
                 Err(error::Error::NoLayoutForOpaqueBlob)
             },

src/codegen/struct_layout.rs

@@ -1,6 +1,6 @@
 //! Helpers for code generation that need struct layout
 
-use super::helpers::BlobTyBuilder;
+use super::helpers;
 
 use aster::struct_field::StructFieldBuilder;
 
@@ -295,7 +295,7 @@ impl<'a, 'ctx> StructLayoutTracker<'a, 'ctx> {
         if self.max_field_align < layout.align &&
             layout.align <= mem::size_of::<*mut ()>()
         {
-            let ty = BlobTyBuilder::new(Layout::new(0, layout.align)).build();
+            let ty = helpers::blob(Layout::new(0, layout.align));
 
             Some(
                 StructFieldBuilder::named("__bindgen_align")
@@ -312,7 +312,7 @@ impl<'a, 'ctx> StructLayoutTracker<'a, 'ctx> {
     }
 
     fn padding_field(&mut self, layout: Layout) -> ast::StructField {
-        let ty = BlobTyBuilder::new(layout).build();
+        let ty = helpers::blob(layout);
         let padding_count = self.padding_count;
 
         self.padding_count += 1;