Generate __BindgenLongDouble

bindgen-tests/tests/headers/long_double.h

@@ -3,3 +3,5 @@
 struct foo {
   long double bar;
 };
+
+void take_ld(long double ld);

bindgen/codegen/helpers.rs

@@ -199,6 +199,7 @@ pub mod ast_ty {
             (FloatKind::LongDouble, ..) => {
                 // TODO(emilio): If rust ever gains f80/f128 we should
                 // use it here and below.
+                ctx.generated_bindgen_long_double(layout.expect("unknown layout for long double"));
                 if ctx.options().enable_cxx_namespaces {
                     quote! {
                         root::__BindgenLongDouble

bindgen/codegen/mod.rs

@@ -217,9 +217,6 @@ struct CodegenResult<'a> {
     /// Whether a bitfield allocation unit has been seen at least once.
     saw_bitfield_unit: bool,
 
-    /// Whether a long double has been seen at least once.
-    saw_long_double: bool,
-
     items_seen: HashSet<ItemId>,
     /// The set of generated function/var names, needed because in C/C++ is
     /// legal to do something like:
@@ -256,7 +253,6 @@ impl<'a> CodegenResult<'a> {
             saw_objc: false,
             saw_block: false,
             saw_bitfield_unit: false,
-            saw_long_double: false,
             codegen_id,
             items_seen: Default::default(),
             functions_seen: Default::default(),
@@ -289,10 +285,6 @@ impl<'a> CodegenResult<'a> {
         self.saw_bitfield_unit = true;
     }
 
-    fn saw_long_double(&mut self) {
-        self.saw_long_double = true;
-    }
-
     fn seen<Id: Into<ItemId>>(&self, item: Id) -> bool {
         self.items_seen.contains(&item.into())
     }
@@ -548,6 +540,9 @@ impl CodeGenerator for Module {
                 if ctx.need_bindgen_complex_type() {
                     utils::prepend_complex_type(&mut *result);
                 }
+                if let Some(layout) = ctx.need_bindgen_long_double() {
+                    utils::prepend_long_double(layout, &mut *result);
+                }
                 if result.saw_objc {
                     utils::prepend_objc_header(ctx, &mut *result);
                 }
@@ -2459,7 +2454,7 @@ impl Method {
 
         let signature = match *signature_item.expect_type().kind() {
             TypeKind::Function(ref sig) => sig,
-            _ => panic!("How in the world?"),
+            _ => unreachable!(),
         };
 
         if utils::sig_unsupported_types(ctx, signature) {
@@ -4513,6 +4508,7 @@ pub mod utils {
     use crate::ir::context::BindgenContext;
     use crate::ir::function::{Abi, ClangAbi, FunctionSig};
     use crate::ir::item::{Item, ItemCanonicalPath};
+    use crate::ir::layout::Layout;
     use crate::ir::ty::TypeKind;
     use proc_macro2;
     use std::borrow::Cow;
@@ -4785,6 +4781,21 @@ pub mod utils {
         result.extend(old_items.into_iter());
     }
 
+    pub fn prepend_long_double(
+        layout: Layout,
+        result: &mut Vec<proc_macro2::TokenStream>,
+    ) {
+        let Layout { align, size, .. } = layout;
+        result.insert(
+            0,
+            quote! {
+                #[derive(PartialEq, Copy, Clone, Hash, Debug, Default)]
+                #[repr(C, align(#align))]
+                pub struct __BindgenLongDouble([u8; #size]);
+            },
+        );
+    }
+
     pub fn build_path(
         item: &Item,
         ctx: &BindgenContext,
@@ -5078,12 +5089,12 @@ pub mod utils {
 
     pub fn sig_unsupported_types(
         ctx: &BindgenContext,
-        sig: &FunctionSig
+        sig: &FunctionSig,
     ) -> bool {
-        sig.argument_types().iter()
+        sig.argument_types()
+            .iter()
             .map(|(_, ty_id)| ty_id)
             .chain(std::iter::once(&sig.return_type()))
-            .find(|ty_id| ctx.lookup_never_by_value(*ty_id))
-            .is_some()
+            .any(|ty_id| ctx.lookup_never_by_value(*ty_id))
     }
 }

bindgen/ir/analysis/never_by_value.rs

@@ -71,7 +71,7 @@ impl<'ctx> NeverByValue<'ctx> {
             was_not_already_in_set,
             "We shouldn't try and insert {:?} twice because if it was \
              already in the set, `constrain` should have exited early.",
-             id
+            id
         );
 
         ConstrainResult::Changed
@@ -128,9 +128,13 @@ impl<'ctx> MonotoneFramework for NeverByValue<'ctx> {
                 }
 
                 TypeKind::Float(..) | TypeKind::Complex(..) => {
-                    let size = ty.layout(self.ctx).expect("float with unknown layout").size;
+                    let size = ty
+                        .layout(self.ctx)
+                        .expect("float with unknown layout")
+                        .size;
                     match (ty.kind(), size) {
-                        (TypeKind::Float(..), 4 | 8) | (TypeKind::Complex(..), 8 | 16) => {
+                        (TypeKind::Float(..), 4 | 8) |
+                        (TypeKind::Complex(..), 8 | 16) => {
                             info!("    skipped f32 or f64");
                             ConstrainResult::Same
                         }
@@ -156,10 +160,9 @@ impl<'ctx> MonotoneFramework for NeverByValue<'ctx> {
                 }
 
                 TypeKind::Comp(ref info) => {
-                    let bases_have = info
-                        .base_members()
-                        .iter()
-                        .any(|base| self.never_by_value.contains(&base.ty.into()));
+                    let bases_have = info.base_members().iter().any(|base| {
+                        self.never_by_value.contains(&base.ty.into())
+                    });
                     if bases_have {
                         info!("    bases have float, so we also have");
                         return self.insert(id);
@@ -168,10 +171,11 @@ impl<'ctx> MonotoneFramework for NeverByValue<'ctx> {
                         Field::DataMember(ref data) => {
                             self.never_by_value.contains(&data.ty().into())
                         }
-                        Field::Bitfields(ref bfu) => bfu
-                            .bitfields()
-                            .iter()
-                            .any(|b| self.never_by_value.contains(&b.ty().into())),
+                        Field::Bitfields(ref bfu) => {
+                            bfu.bitfields().iter().any(|b| {
+                                self.never_by_value.contains(&b.ty().into())
+                            })
+                        }
                     });
                     if fields_have {
                         info!("    fields have float, so we also have");

bindgen/ir/context.rs

@@ -4,8 +4,8 @@ use super::super::time::Timer;
 use super::analysis::{
     analyze, as_cannot_derive_set, CannotDerive, DeriveTrait,
     HasDestructorAnalysis, HasFloat, HasTypeParameterInArray,
-    HasVtableAnalysis, HasVtableResult, NeverByValue,
-    SizednessAnalysis, SizednessResult, UsedTemplateParameters,
+    HasVtableAnalysis, HasVtableResult, NeverByValue, SizednessAnalysis,
+    SizednessResult, UsedTemplateParameters,
 };
 use super::derive::{
     CanDerive, CanDeriveCopy, CanDeriveDebug, CanDeriveDefault, CanDeriveEq,
@@ -20,6 +20,7 @@ use super::template::{TemplateInstantiation, TemplateParameters};
 use super::traversal::{self, Edge, ItemTraversal};
 use super::ty::{FloatKind, Type, TypeKind};
 use crate::clang::{self, Cursor};
+use crate::ir::layout::Layout;
 use crate::BindgenOptions;
 use crate::{Entry, HashMap, HashSet};
 use cexpr;
@@ -375,6 +376,9 @@ pub struct BindgenContext {
     /// Whether a bindgen complex was generated
     generated_bindgen_complex: Cell<bool>,
 
+    /// Whether a bindgen long double was generated
+    generated_bindgen_long_double: Cell<Option<Layout>>,
+
     /// The set of `ItemId`s that are allowlisted. This the very first thing
     /// computed after parsing our IR, and before running any of our analyses.
     allowlisted: Option<ItemSet>,
@@ -584,6 +588,7 @@ If you encounter an error missing from this list, please file an issue or a PR!"
             target_info,
             options,
             generated_bindgen_complex: Cell::new(false),
+            generated_bindgen_long_double: Cell::new(None),
             allowlisted: None,
             blocklisted_types_implement_traits: Default::default(),
             codegen_items: None,
@@ -2504,6 +2509,20 @@ If you encounter an error missing from this list, please file an issue or a PR!"
         self.generated_bindgen_complex.get()
     }
 
+    /// Call if a bindgen long double is generated
+    pub fn generated_bindgen_long_double(&self, layout: Layout) {
+        if let Some(old) =
+            self.generated_bindgen_long_double.replace(Some(layout))
+        {
+            assert_eq!(layout, old, "long doubles had different layout");
+        }
+    }
+
+    /// Whether we need to generate the bindgen long double type (and if so, get its layout)
+    pub fn need_bindgen_long_double(&self) -> Option<Layout> {
+        self.generated_bindgen_long_double.get()
+    }
+
     /// Compute which `enum`s have an associated `typedef` definition.
     fn compute_enum_typedef_combos(&mut self) {
         let _t = self.timer("compute_enum_typedef_combos");