Block function bindings which pass extended floats by value rust-lang#2403

Author: GKFX

bindgen-tests/tests/expectations/tests/complex_global.rs

@@ -0,0 +1,9 @@
+// bindgen-flags: -- --target=x86_64-pc-windows-msvc
+
+struct foo {
+  float bar, baz;
+  double bazz;
+  long double* bazzz;
+  float _Complex complexFloat;
+  double _Complex complexDouble;
+};

bindgen-tests/tests/expectations/tests/convert-floats-win64.rs

@@ -1,4 +1,4 @@
-// bindgen-flags: --no-convert-floats
+// bindgen-flags: --no-convert-floats -- --target=x86_64-unknown-linux-gnu
 
 struct foo {
   float bar, baz;

bindgen-tests/tests/expectations/tests/convert-floats.rs

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

bindgen-tests/tests/expectations/tests/long_double.rs

@@ -225,39 +225,46 @@ pub(crate) mod ast_ty {
     pub(crate) fn float_kind_rust_type(
         ctx: &BindgenContext,
         fk: FloatKind,
-        layout: Option<Layout>,
+        mut layout: Option<Layout>,
+        n_parts: usize,
     ) -> syn::Type {
-        // TODO: we probably should take the type layout into account more
-        // often?
-        //
-        // Also, maybe this one shouldn't be the default?
-        match (fk, ctx.options().convert_floats) {
-            (FloatKind::Float, true) => syn::parse_quote! { f32 },
-            (FloatKind::Double, true) => syn::parse_quote! { f64 },
-            (FloatKind::Float, false) => raw_type(ctx, "c_float"),
-            (FloatKind::Double, false) => raw_type(ctx, "c_double"),
-            (FloatKind::LongDouble, _) => {
-                match layout {
-                    Some(layout) => {
-                        match layout.size {
-                            4 => syn::parse_quote! { f32 },
-                            8 => syn::parse_quote! { f64 },
-                            // TODO(emilio): If rust ever gains f128 we should
-                            // use it here and below.
-                            _ => super::integer_type(ctx, layout)
-                                .unwrap_or(syn::parse_quote! { f64 }),
-                        }
+        // Convert the layout of complex numbers to the layout of its parts.
+        let bits = match layout {
+            Some(Layout { ref mut size, .. }) => {
+                *size /= n_parts;
+                Some(*size * 8)
+            }
+            None => None,
+        };
+        match (fk, ctx.options().convert_floats, bits) {
+            // With convert_floats=True, turn 32-bit and 64-bit floats into
+            // f32 and f64, regardless of whether they were written as float,
+            // double, long double, etc.
+            // TODO: What about narrower floats?
+            (_, true, Some(32)) => syn::parse_quote! { f32 },
+            (_, true, Some(64)) | (FloatKind::Double, true, None) => {
+                syn::parse_quote! { f64 }
+            }
+
+            (FloatKind::Float, ..) => raw_type(ctx, "c_float"),
+            (FloatKind::Double, ..) => raw_type(ctx, "c_double"),
+            (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 {
+                    syn::parse_quote! {
+                        root::__BindgenLongDouble
                     }
-                    None => {
-                        debug_assert!(
-                            false,
-                            "How didn't we know the layout for a primitive type?"
-                        );
-                        syn::parse_quote! { f64 }
+                } else {
+                    syn::parse_quote! {
+                        __BindgenLongDouble
                     }
                 }
             }
-            (FloatKind::Float128, _) => {
+            (FloatKind::Float128, ..) => {
                 if ctx.options().rust_features.i128_and_u128 {
                     syn::parse_quote! { u128 }
                 } else {

bindgen-tests/tests/headers/convert-floats-win64.h

@@ -580,6 +580,9 @@ 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);
                 }
@@ -2604,6 +2607,10 @@ impl Method {
             return;
         }
 
+        if utils::sig_unsupported_types(ctx, signature) {
+            return;
+        }
+
         // Do not generate variadic methods, since rust does not allow
         // implementing them, and we don't do a good job at it anyway.
         if signature.is_variadic() {
@@ -3848,11 +3855,11 @@ impl TryToRustTy for Type {
                 Ok(int_kind_rust_type(ctx, ik, self.layout(ctx)))
             }
             TypeKind::Float(fk) => {
-                Ok(float_kind_rust_type(ctx, fk, self.layout(ctx)))
+                Ok(float_kind_rust_type(ctx, fk, self.layout(ctx), 1))
             }
             TypeKind::Complex(fk) => {
                 let float_path =
-                    float_kind_rust_type(ctx, fk, self.layout(ctx));
+                    float_kind_rust_type(ctx, fk, self.layout(ctx), 2);
 
                 ctx.generated_bindgen_complex();
                 Ok(if ctx.options().enable_cxx_namespaces {
@@ -4197,6 +4204,11 @@ impl CodeGenerator for Function {
             Ok(abi) => abi,
         };
 
+        if utils::sig_unsupported_types(ctx, signature) {
+            warn!("Skipping function which passes or returns by value types not available in Rust.");
+            return None;
+        }
+
         // Handle overloaded functions by giving each overload its own unique
         // suffix.
         let times_seen = result.overload_number(&canonical_name);
@@ -4745,6 +4757,7 @@ pub(crate) mod utils {
     use crate::ir::context::TypeId;
     use crate::ir::function::{Abi, ClangAbi, FunctionSig};
     use crate::ir::item::{Item, ItemCanonicalPath};
+    use crate::ir::layout::Layout;
     use crate::ir::ty::TypeKind;
     use crate::{args_are_cpp, file_is_cpp};
     use std::borrow::Cow;
@@ -5139,6 +5152,23 @@ pub(crate) mod utils {
         result.extend(old_items);
     }
 
+    pub(crate) fn prepend_long_double(
+        layout: Layout,
+        result: &mut Vec<proc_macro2::TokenStream>,
+    ) {
+        let Layout { align, size, .. } = layout;
+        let align = proc_macro2::Literal::u64_unsuffixed(align as u64);
+        let size = proc_macro2::Literal::u64_unsuffixed(size as u64);
+        result.insert(
+            0,
+            quote! {
+                #[derive(PartialEq, Copy, Clone, Hash, Debug, Default)]
+                #[repr(C, align(#align))]
+                pub struct __BindgenLongDouble([u8; #size]);
+            },
+        );
+    }
+
     pub(crate) fn build_path(
         item: &Item,
         ctx: &BindgenContext,
@@ -5431,4 +5461,15 @@ pub(crate) mod utils {
 
         true
     }
+
+    pub(crate) fn sig_unsupported_types(
+        ctx: &BindgenContext,
+        sig: &FunctionSig,
+    ) -> bool {
+        sig.argument_types()
+            .iter()
+            .map(|(_, ty_id)| ty_id)
+            .chain(std::iter::once(&sig.return_type()))
+            .any(|ty_id| ctx.lookup_never_by_value(*ty_id))
+    }
 }

bindgen-tests/tests/headers/convert-floats.h

@@ -53,6 +53,8 @@ mod has_type_param_in_array;
 pub(crate) use self::has_type_param_in_array::HasTypeParameterInArray;
 mod has_float;
 pub(crate) use self::has_float::HasFloat;
+mod never_by_value;
+pub use self::never_by_value::NeverByValue;
 mod sizedness;
 pub(crate) use self::sizedness::{
     Sizedness, SizednessAnalysis, SizednessResult,