Rollup merge of #52635 - yodaldevoid:issue_18804, r=oli-obk
Fix #[linkage] propagation though generic functions Fixes #18804 In the non-local branch of `get_static` (where the fix was implemented) `span_fatal` had to be replaced with `bug!` as we have no span in that case.
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c7555cedde
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@ -20,12 +20,14 @@ use monomorphize::MonoItem;
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use common::{CodegenCx, val_ty};
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use declare;
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use monomorphize::Instance;
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use syntax_pos::Span;
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use syntax_pos::symbol::LocalInternedString;
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use type_::Type;
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use type_of::LayoutLlvmExt;
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use rustc::ty;
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use rustc::ty::{self, Ty};
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use rustc::ty::layout::{Align, LayoutOf};
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use rustc::hir::{self, CodegenFnAttrFlags};
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use rustc::hir::{self, CodegenFnAttrs, CodegenFnAttrFlags};
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use std::ffi::{CStr, CString};
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@ -119,6 +121,8 @@ pub fn get_static(cx: &CodegenCx, def_id: DefId) -> ValueRef {
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let ty = instance.ty(cx.tcx);
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let sym = cx.tcx.symbol_name(instance).as_str();
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debug!("get_static: sym={} instance={:?}", sym, instance);
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let g = if let Some(id) = cx.tcx.hir.as_local_node_id(def_id) {
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let llty = cx.layout_of(ty).llvm_type(cx);
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@ -144,50 +148,15 @@ pub fn get_static(cx: &CodegenCx, def_id: DefId) -> ValueRef {
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hir_map::NodeForeignItem(&hir::ForeignItem {
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ref attrs, span, node: hir::ForeignItemKind::Static(..), ..
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}) => {
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let g = if let Some(linkage) = cx.tcx.codegen_fn_attrs(def_id).linkage {
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// If this is a static with a linkage specified, then we need to handle
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// it a little specially. The typesystem prevents things like &T and
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// extern "C" fn() from being non-null, so we can't just declare a
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// static and call it a day. Some linkages (like weak) will make it such
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// that the static actually has a null value.
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let llty2 = match ty.sty {
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ty::TyRawPtr(ref mt) => cx.layout_of(mt.ty).llvm_type(cx),
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_ => {
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cx.sess().span_fatal(span, "must have type `*const T` or `*mut T`");
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}
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};
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unsafe {
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// Declare a symbol `foo` with the desired linkage.
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let g1 = declare::declare_global(cx, &sym, llty2);
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llvm::LLVMRustSetLinkage(g1, base::linkage_to_llvm(linkage));
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// Declare an internal global `extern_with_linkage_foo` which
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// is initialized with the address of `foo`. If `foo` is
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// discarded during linking (for example, if `foo` has weak
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// linkage and there are no definitions), then
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// `extern_with_linkage_foo` will instead be initialized to
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// zero.
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let mut real_name = "_rust_extern_with_linkage_".to_string();
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real_name.push_str(&sym);
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let g2 = declare::define_global(cx, &real_name, llty).unwrap_or_else(||{
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cx.sess().span_fatal(span,
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&format!("symbol `{}` is already defined", &sym))
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});
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llvm::LLVMRustSetLinkage(g2, llvm::Linkage::InternalLinkage);
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llvm::LLVMSetInitializer(g2, g1);
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g2
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}
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} else {
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// Generate an external declaration.
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declare::declare_global(cx, &sym, llty)
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};
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(g, attrs)
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let fn_attrs = cx.tcx.codegen_fn_attrs(def_id);
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(check_and_apply_linkage(cx, &fn_attrs, ty, sym, Some(span)), attrs)
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}
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item => bug!("get_static: expected static, found {:?}", item)
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};
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debug!("get_static: sym={} attrs={:?}", sym, attrs);
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for attr in attrs {
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if attr.check_name("thread_local") {
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llvm::set_thread_local_mode(g, cx.tls_model);
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@ -197,19 +166,21 @@ pub fn get_static(cx: &CodegenCx, def_id: DefId) -> ValueRef {
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g
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} else {
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// FIXME(nagisa): perhaps the map of externs could be offloaded to llvm somehow?
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// FIXME(nagisa): investigate whether it can be changed into define_global
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let g = declare::declare_global(cx, &sym, cx.layout_of(ty).llvm_type(cx));
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debug!("get_static: sym={} item_attr={:?}", sym, cx.tcx.item_attrs(def_id));
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let attrs = cx.tcx.codegen_fn_attrs(def_id);
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let g = check_and_apply_linkage(cx, &attrs, ty, sym, None);
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// Thread-local statics in some other crate need to *always* be linked
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// against in a thread-local fashion, so we need to be sure to apply the
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// thread-local attribute locally if it was present remotely. If we
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// don't do this then linker errors can be generated where the linker
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// complains that one object files has a thread local version of the
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// symbol and another one doesn't.
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for attr in cx.tcx.get_attrs(def_id).iter() {
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if attr.check_name("thread_local") {
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if attrs.flags.contains(CodegenFnAttrFlags::THREAD_LOCAL) {
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llvm::set_thread_local_mode(g, cx.tls_model);
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}
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}
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if cx.use_dll_storage_attrs && !cx.tcx.is_foreign_item(def_id) {
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// This item is external but not foreign, i.e. it originates from an external Rust
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// crate. Since we don't know whether this crate will be linked dynamically or
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@ -242,6 +213,66 @@ pub fn get_static(cx: &CodegenCx, def_id: DefId) -> ValueRef {
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g
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}
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fn check_and_apply_linkage<'tcx>(
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cx: &CodegenCx<'_, 'tcx>,
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attrs: &CodegenFnAttrs,
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ty: Ty<'tcx>,
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sym: LocalInternedString,
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span: Option<Span>
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) -> ValueRef {
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let llty = cx.layout_of(ty).llvm_type(cx);
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if let Some(linkage) = attrs.linkage {
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debug!("get_static: sym={} linkage={:?}", sym, linkage);
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// If this is a static with a linkage specified, then we need to handle
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// it a little specially. The typesystem prevents things like &T and
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// extern "C" fn() from being non-null, so we can't just declare a
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// static and call it a day. Some linkages (like weak) will make it such
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// that the static actually has a null value.
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let llty2 = match ty.sty {
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ty::TyRawPtr(ref mt) => cx.layout_of(mt.ty).llvm_type(cx),
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_ => {
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if span.is_some() {
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cx.sess().span_fatal(span.unwrap(), "must have type `*const T` or `*mut T`")
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} else {
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bug!("must have type `*const T` or `*mut T`")
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}
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}
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};
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unsafe {
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// Declare a symbol `foo` with the desired linkage.
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let g1 = declare::declare_global(cx, &sym, llty2);
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llvm::LLVMRustSetLinkage(g1, base::linkage_to_llvm(linkage));
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// Declare an internal global `extern_with_linkage_foo` which
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// is initialized with the address of `foo`. If `foo` is
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// discarded during linking (for example, if `foo` has weak
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// linkage and there are no definitions), then
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// `extern_with_linkage_foo` will instead be initialized to
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// zero.
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let mut real_name = "_rust_extern_with_linkage_".to_string();
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real_name.push_str(&sym);
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let g2 = declare::define_global(cx, &real_name, llty).unwrap_or_else(||{
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if span.is_some() {
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cx.sess().span_fatal(
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span.unwrap(),
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&format!("symbol `{}` is already defined", &sym)
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)
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} else {
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bug!("symbol `{}` is already defined", &sym)
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}
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});
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llvm::LLVMRustSetLinkage(g2, llvm::Linkage::InternalLinkage);
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llvm::LLVMSetInitializer(g2, g1);
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g2
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}
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} else {
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// Generate an external declaration.
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// FIXME(nagisa): investigate whether it can be changed into define_global
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declare::declare_global(cx, &sym, llty)
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}
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}
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pub fn codegen_static<'a, 'tcx>(
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cx: &CodegenCx<'a, 'tcx>,
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def_id: DefId,
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@ -0,0 +1,20 @@
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// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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#![crate_type = "rlib"]
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#![feature(linkage)]
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pub fn foo<T>() -> *const() {
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extern {
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#[linkage = "extern_weak"]
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static FOO: *const();
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}
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unsafe { FOO }
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}
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@ -0,0 +1,23 @@
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// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// Test for issue #18804, #[linkage] does not propagate thorugh generic
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// functions. Failure results in a linker error.
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// ignore-asmjs no weak symbol support
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// ignore-emscripten no weak symbol support
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// aux-build:lib.rs
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extern crate lib;
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fn main() {
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lib::foo::<i32>();
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}
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