use rustc_codegen_ssa::traits::PreDefineMethods;
use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
use rustc_middle::mir::mono::{Linkage, Visibility};
use rustc_middle::ty::{self, Instance, TypeFoldable};
use rustc_middle::ty::layout::{FnAbiExt, LayoutOf};
use rustc_span::def_id::DefId;
use rustc_target::abi::call::FnAbi;

use crate::base;
use crate::context::CodegenCx;
use crate::type_of::LayoutGccExt;

impl<'gcc, 'tcx> PreDefineMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
    fn predefine_static(&self, def_id: DefId, _linkage: Linkage, _visibility: Visibility, symbol_name: &str) {
        let attrs = self.tcx.codegen_fn_attrs(def_id);
        let instance = Instance::mono(self.tcx, def_id);
        let ty = instance.ty(self.tcx, ty::ParamEnv::reveal_all());
        let gcc_type = self.layout_of(ty).gcc_type(self, true);

        let is_tls = attrs.flags.contains(CodegenFnAttrFlags::THREAD_LOCAL);
        let global = self.define_global(symbol_name, gcc_type, is_tls, attrs.link_section).unwrap_or_else(|| {
            self.sess().span_fatal(
                self.tcx.def_span(def_id),
                &format!("symbol `{}` is already defined", symbol_name),
            )
        });

        // TODO(antoyo): set linkage and visibility.
        self.instances.borrow_mut().insert(instance, global);
    }

    fn predefine_fn(&self, instance: Instance<'tcx>, linkage: Linkage, _visibility: Visibility, symbol_name: &str) {
        assert!(!instance.substs.needs_infer());

        let fn_abi = FnAbi::of_instance(self, instance, &[]);
        self.linkage.set(base::linkage_to_gcc(linkage));
        let _decl = self.declare_fn(symbol_name, &fn_abi);
        //let attrs = self.tcx.codegen_fn_attrs(instance.def_id());

        // TODO(antoyo): call set_link_section() to allow initializing argc/argv.
        // TODO(antoyo): set unique comdat.
        // TODO(antoyo): use inline attribute from there in linkage.set() above.
    }
}