Add to va_list lang item

Add the va_list lang item in order to allow VaList in libcore to be
correctly generated for the target arch by trans.

Author: dlrobertson

src/libcore/lib.rs

@@ -189,6 +189,7 @@ pub mod iter;
 pub mod option;
 pub mod raw;
 pub mod result;
+pub mod va_list;
 
 pub mod slice;
 pub mod str;

src/libcore/va_list.rs

@@ -0,0 +1,48 @@
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![unstable(feature = "c_variadic",
+            reason = "dlrobertson is still working on this",
+            issue = "27745")]
+
+//! Implementation of a `va_list`
+
+#[cfg(not(stage0))]
+#[lang = "va_list"]
+/// A wrapper for a `va_list`
+//#[derive(Debug)]
+#[repr(C)]
+#[unstable(feature = "c_variadic",
+           reason = "dlrobertson is still working on this",
+           issue = "27745")]
+#[derive(Debug)]
+pub struct VaList;
+
+#[cfg(not(stage0))]
+#[unstable(feature = "c_variadic",
+           reason = "This is just a test.",
+           issue = "27745")]
+impl VaList {
+    /// Advance to the next arg.
+    pub unsafe fn arg<T: Copy>(&mut self) -> T {
+        let tmp = self as *mut _ as *mut i8;
+        ::intrinsics::va_arg(tmp)
+    }
+
+    /// Copy the `va_list` at the current location.
+    pub unsafe fn copy<'ret, F, T>(&self, f: F) -> T
+            where F: FnOnce(&mut VaList) -> T, T: 'ret {
+        let mut ap: VaList = ::mem::uninitialized::<VaList>();
+        ::intrinsics::va_copy(self as *const _ as *const i8, &mut ap as *mut _ as *mut i8);
+        let ret = f(&mut ap);
+        ::intrinsics::va_end(&mut ap as *const _ as *mut i8);
+        ret
+    }
+}

src/librustc/middle/lang_items.rs

@@ -273,6 +273,7 @@ language_item_table! {
     IndexMutTraitLangItem,           "index_mut",               index_mut_trait;
 
     UnsafeCellTypeLangItem,          "unsafe_cell",             unsafe_cell_type;
+    VaListTypeLangItem,              "va_list",                 va_list;
 
     DerefTraitLangItem,              "deref",                   deref_trait;
     DerefMutTraitLangItem,           "deref_mut",               deref_mut_trait;

src/librustc/ty/context.rs

@@ -53,6 +53,7 @@ use ty::BindingMode;
 use ty::CanonicalTy;
 use util::nodemap::{DefIdSet, ItemLocalMap};
 use util::nodemap::{FxHashMap, FxHashSet};
+use rustc_target::spec::VaListKind;
 use rustc_data_structures::accumulate_vec::AccumulateVec;
 use rustc_data_structures::stable_hasher::{HashStable, hash_stable_hashmap,
                                            StableHasher, StableHasherResult,
@@ -2694,6 +2695,34 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
         self.object_lifetime_defaults_map(id.owner)
             .and_then(|map| map.get(&id.local_id).cloned())
     }
+
+    pub fn va_list_types(&self) -> Vec<Ty<'tcx>> {
+        match self.sess.target.target.options.va_list_kind {
+            VaListKind::CharPtr | VaListKind::VoidPtr => {
+                vec![self.mk_mut_ptr(self.types.i8)]
+            }
+            VaListKind::X86_64Abi => {
+                vec![self.types.i32,
+                     self.types.i32,
+                     self.mk_mut_ptr(self.types.i8),
+                     self.mk_mut_ptr(self.types.i8)]
+            }
+            VaListKind::AArch64Abi => {
+                vec![self.mk_mut_ptr(self.types.i8),
+                     self.mk_mut_ptr(self.types.i8),
+                     self.mk_mut_ptr(self.types.i8),
+                     self.types.i32,
+                     self.types.i32]
+            }
+            VaListKind::PowerPcAbi => {
+                vec![self.types.i8,
+                     self.types.i8,
+                     self.types.i16,
+                     self.mk_mut_ptr(self.types.i8),
+                     self.mk_mut_ptr(self.types.i8)]
+            }
+        }
+    }
 }
 
 pub trait InternAs<T: ?Sized, R> {

src/librustc/ty/layout.rs

@@ -744,7 +744,17 @@ impl<'a, 'tcx> LayoutCx<'tcx, TyCtxt<'a, 'tcx, 'tcx>> {
                         else { StructKind::AlwaysSized }
                     };
 
-                    let mut st = univariant_uninterned(&variants[v], &def.repr, kind)?;
+                    let mut st = match tcx.lang_items().va_list() {
+                        Some(did) if did == def.did => {
+                            let variants = tcx.va_list_types().iter()
+                                                              .map(|x| self.layout_of(x).unwrap())
+                                                              .collect::<Vec<_>>();
+                            univariant_uninterned(&variants[..], &def.repr, kind)?
+                        }
+                        _ => {
+                            univariant_uninterned(&variants[v], &def.repr, kind)?
+                        }
+                    };
                     st.variants = Variants::Single { index: v };
                     // Exclude 0 from the range of a newtype ABI NonZero<T>.
                     if Some(def.did) == self.tcx.lang_items().non_zero() {
@@ -1614,6 +1624,13 @@ impl<'a, 'tcx, C> TyLayoutMethods<'tcx, C> for Ty<'tcx>
                 this.ty.simd_type(tcx)
             }
 
+            ty::TyAdt(def, ..) if Some(def.did) == tcx.lang_items().va_list() => {
+                match this.variants {
+                    Variants::Single { index } => tcx.va_list_types()[index],
+                    _ => bug!("VaList must be a struct type with a single variant.")
+                }
+            }
+
             // ADTs.
             ty::TyAdt(def, substs) => {
                 match this.variants {

src/librustc_trans/type_of.rs

@@ -103,9 +103,16 @@ fn uncached_llvm_type<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
                     Type::struct_(cx, &llfields, packed)
                 }
                 Some(ref name) => {
-                    let llty = Type::named_struct(cx, name);
-                    *defer = Some((llty, layout));
-                    llty
+                    match layout.ty.sty {
+                        ty::TyAdt(def, _) if Some(def.did) == cx.tcx.lang_items().va_list() => {
+                            Type::va_list(cx, name)
+                        }
+                        _ => {
+                            let llty = Type::named_struct(cx, name);
+                            *defer = Some((llty, layout));
+                            llty
+                        }
+                    }
                 }
             }
         }

src/librustdoc/clean/inline.rs

@@ -297,6 +297,7 @@ pub fn build_impls(cx: &DocContext, did: DefId, auto_traits: bool) -> Vec<clean:
         lang_items.slice_u8_alloc_impl(),
         lang_items.const_ptr_impl(),
         lang_items.mut_ptr_impl(),
+        lang_items.va_list(),
     ];
 
     for def_id in primitive_impls.iter().filter_map(|&def_id| def_id) {