#![allow(rustc::diagnostic_outside_of_impl)]
#![allow(rustc::untranslatable_diagnostic)]
#![feature(if_let_guard)]
#![feature(let_chains)]
#![feature(try_blocks)]
#![feature(never_type)]
#![feature(box_patterns)]
#![feature(control_flow_enum)]

#[macro_use]
extern crate tracing;

#[macro_use]
extern crate rustc_middle;

mod _match;
mod autoderef;
mod callee;
// Used by clippy;
pub mod cast;
mod check;
mod closure;
mod coercion;
mod demand;
mod diverges;
mod errors;
mod expectation;
mod expr;
// Used by clippy;
pub mod expr_use_visitor;
mod fallback;
mod fn_ctxt;
mod gather_locals;
mod intrinsicck;
mod mem_categorization;
mod method;
mod op;
mod pat;
mod place_op;
mod rvalue_scopes;
mod typeck_root_ctxt;
mod upvar;
mod writeback;

pub use coercion::can_coerce;
use fn_ctxt::FnCtxt;
use typeck_root_ctxt::TypeckRootCtxt;

use crate::check::check_fn;
use crate::coercion::DynamicCoerceMany;
use crate::diverges::Diverges;
use crate::expectation::Expectation;
use crate::fn_ctxt::LoweredTy;
use crate::gather_locals::GatherLocalsVisitor;
use rustc_data_structures::unord::UnordSet;
use rustc_errors::{codes::*, struct_span_code_err, ErrorGuaranteed};
use rustc_hir as hir;
use rustc_hir::def::{DefKind, Res};
use rustc_hir::intravisit::Visitor;
use rustc_hir::{HirId, HirIdMap, Node};
use rustc_hir_analysis::check::check_abi;
use rustc_hir_analysis::hir_ty_lowering::HirTyLowerer;
use rustc_infer::infer::type_variable::TypeVariableOrigin;
use rustc_infer::traits::{ObligationCauseCode, ObligationInspector, WellFormedLoc};
use rustc_middle::query::Providers;
use rustc_middle::traits;
use rustc_middle::ty::{self, Ty, TyCtxt};
use rustc_session::config;
use rustc_span::def_id::LocalDefId;
use rustc_span::Span;

rustc_fluent_macro::fluent_messages! { "../messages.ftl" }

#[macro_export]
macro_rules! type_error_struct {
    ($dcx:expr, $span:expr, $typ:expr, $code:expr, $($message:tt)*) => ({
        let mut err = rustc_errors::struct_span_code_err!($dcx, $span, $code, $($message)*);

        if $typ.references_error() {
            err.downgrade_to_delayed_bug();
        }

        err
    })
}

fn used_trait_imports(tcx: TyCtxt<'_>, def_id: LocalDefId) -> &UnordSet<LocalDefId> {
    &tcx.typeck(def_id).used_trait_imports
}

fn typeck<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> &ty::TypeckResults<'tcx> {
    let fallback = move || tcx.type_of(def_id.to_def_id()).instantiate_identity();
    typeck_with_fallback(tcx, def_id, fallback, None)
}

/// Used only to get `TypeckResults` for type inference during error recovery.
/// Currently only used for type inference of `static`s and `const`s to avoid type cycle errors.
fn diagnostic_only_typeck<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> &ty::TypeckResults<'tcx> {
    let fallback = move || {
        let span = tcx.hir().span(tcx.local_def_id_to_hir_id(def_id));
        Ty::new_error_with_message(tcx, span, "diagnostic only typeck table used")
    };
    typeck_with_fallback(tcx, def_id, fallback, None)
}

/// Same as `typeck` but `inspect` is invoked on evaluation of each root obligation.
/// Inspecting obligations only works with the new trait solver.
/// This function is *only to be used* by external tools, it should not be
/// called from within rustc. Note, this is not a query, and thus is not cached.
pub fn inspect_typeck<'tcx>(
    tcx: TyCtxt<'tcx>,
    def_id: LocalDefId,
    inspect: ObligationInspector<'tcx>,
) -> &'tcx ty::TypeckResults<'tcx> {
    let fallback = move || tcx.type_of(def_id.to_def_id()).instantiate_identity();
    typeck_with_fallback(tcx, def_id, fallback, Some(inspect))
}

#[instrument(level = "debug", skip(tcx, fallback, inspector), ret)]
fn typeck_with_fallback<'tcx>(
    tcx: TyCtxt<'tcx>,
    def_id: LocalDefId,
    fallback: impl Fn() -> Ty<'tcx> + 'tcx,
    inspector: Option<ObligationInspector<'tcx>>,
) -> &'tcx ty::TypeckResults<'tcx> {
    // Closures' typeck results come from their outermost function,
    // as they are part of the same "inference environment".
    let typeck_root_def_id = tcx.typeck_root_def_id(def_id.to_def_id()).expect_local();
    if typeck_root_def_id != def_id {
        return tcx.typeck(typeck_root_def_id);
    }

    let id = tcx.local_def_id_to_hir_id(def_id);
    let node = tcx.hir_node(id);
    let span = tcx.hir().span(id);

    // Figure out what primary body this item has.
    let body_id = node.body_id().unwrap_or_else(|| {
        span_bug!(span, "can't type-check body of {:?}", def_id);
    });
    let body = tcx.hir().body(body_id);

    let param_env = tcx.param_env(def_id);

    let root_ctxt = TypeckRootCtxt::new(tcx, def_id);
    if let Some(inspector) = inspector {
        root_ctxt.infcx.attach_obligation_inspector(inspector);
    }
    let mut fcx = FnCtxt::new(&root_ctxt, param_env, def_id);

    if let Some(hir::FnSig { header, decl, .. }) = node.fn_sig() {
        let fn_sig = if decl.output.get_infer_ret_ty().is_some() {
            fcx.lowerer().lower_fn_ty(id, header.unsafety, header.abi, decl, None, None)
        } else {
            tcx.fn_sig(def_id).instantiate_identity()
        };

        check_abi(tcx, id, span, fn_sig.abi());

        // Compute the function signature from point of view of inside the fn.
        let fn_sig = tcx.liberate_late_bound_regions(def_id.to_def_id(), fn_sig);
        let fn_sig = fcx.normalize(body.value.span, fn_sig);

        check_fn(&mut fcx, fn_sig, None, decl, def_id, body, tcx.features().unsized_fn_params);
    } else {
        let expected_type = infer_type_if_missing(&fcx, node);
        let expected_type = expected_type.unwrap_or_else(fallback);

        let expected_type = fcx.normalize(body.value.span, expected_type);

        let wf_code = ObligationCauseCode::WellFormed(Some(WellFormedLoc::Ty(def_id)));
        fcx.register_wf_obligation(expected_type.into(), body.value.span, wf_code);

        fcx.require_type_is_sized(expected_type, body.value.span, traits::ConstSized);

        // Gather locals in statics (because of block expressions).
        GatherLocalsVisitor::new(&fcx).visit_body(body);

        fcx.check_expr_coercible_to_type(body.value, expected_type, None);

        fcx.write_ty(id, expected_type);
    };

    fcx.type_inference_fallback();

    // Even though coercion casts provide type hints, we check casts after fallback for
    // backwards compatibility. This makes fallback a stronger type hint than a cast coercion.
    fcx.check_casts();
    fcx.select_obligations_where_possible(|_| {});

    // Closure and coroutine analysis may run after fallback
    // because they don't constrain other type variables.
    fcx.closure_analyze(body);
    assert!(fcx.deferred_call_resolutions.borrow().is_empty());
    // Before the coroutine analysis, temporary scopes shall be marked to provide more
    // precise information on types to be captured.
    fcx.resolve_rvalue_scopes(def_id.to_def_id());

    for (ty, span, code) in fcx.deferred_sized_obligations.borrow_mut().drain(..) {
        let ty = fcx.normalize(span, ty);
        fcx.require_type_is_sized(ty, span, code);
    }

    fcx.select_obligations_where_possible(|_| {});

    debug!(pending_obligations = ?fcx.fulfillment_cx.borrow().pending_obligations());

    // This must be the last thing before `report_ambiguity_errors`.
    fcx.resolve_coroutine_interiors();

    debug!(pending_obligations = ?fcx.fulfillment_cx.borrow().pending_obligations());

    if let None = fcx.infcx.tainted_by_errors() {
        fcx.report_ambiguity_errors();
    }

    if let None = fcx.infcx.tainted_by_errors() {
        fcx.check_transmutes();
    }

    fcx.check_asms();

    let typeck_results = fcx.resolve_type_vars_in_body(body);

    // We clone the defined opaque types during writeback in the new solver
    // because we have to use them during normalization.
    let _ = fcx.infcx.take_opaque_types();

    // Consistency check our TypeckResults instance can hold all ItemLocalIds
    // it will need to hold.
    assert_eq!(typeck_results.hir_owner, id.owner);

    typeck_results
}

fn infer_type_if_missing<'tcx>(fcx: &FnCtxt<'_, 'tcx>, node: Node<'tcx>) -> Option<Ty<'tcx>> {
    let tcx = fcx.tcx;
    let def_id = fcx.body_id;
    let expected_type = if let Some(&hir::Ty { kind: hir::TyKind::Infer, span, .. }) = node.ty() {
        if let Some(item) = tcx.opt_associated_item(def_id.into())
            && let ty::AssocKind::Const = item.kind
            && let ty::ImplContainer = item.container
            && let Some(trait_item) = item.trait_item_def_id
        {
            let args =
                tcx.impl_trait_ref(item.container_id(tcx)).unwrap().instantiate_identity().args;
            Some(tcx.type_of(trait_item).instantiate(tcx, args))
        } else {
            Some(fcx.next_ty_var(TypeVariableOrigin { span, param_def_id: None }))
        }
    } else if let Node::AnonConst(_) = node {
        let id = tcx.local_def_id_to_hir_id(def_id);
        match tcx.parent_hir_node(id) {
            Node::Ty(&hir::Ty { kind: hir::TyKind::Typeof(ref anon_const), span, .. })
                if anon_const.hir_id == id =>
            {
                Some(fcx.next_ty_var(TypeVariableOrigin { span, param_def_id: None }))
            }
            Node::Expr(&hir::Expr { kind: hir::ExprKind::InlineAsm(asm), span, .. })
            | Node::Item(&hir::Item { kind: hir::ItemKind::GlobalAsm(asm), span, .. }) => {
                asm.operands.iter().find_map(|(op, _op_sp)| match op {
                    hir::InlineAsmOperand::Const { anon_const } if anon_const.hir_id == id => {
                        // Inline assembly constants must be integers.
                        Some(fcx.next_int_var())
                    }
                    hir::InlineAsmOperand::SymFn { anon_const } if anon_const.hir_id == id => {
                        Some(fcx.next_ty_var(TypeVariableOrigin { span, param_def_id: None }))
                    }
                    _ => None,
                })
            }
            _ => None,
        }
    } else {
        None
    };
    expected_type
}

/// When `check_fn` is invoked on a coroutine (i.e., a body that
/// includes yield), it returns back some information about the yield
/// points.
#[derive(Debug, PartialEq, Copy, Clone)]
struct CoroutineTypes<'tcx> {
    /// Type of coroutine argument / values returned by `yield`.
    resume_ty: Ty<'tcx>,

    /// Type of value that is yielded.
    yield_ty: Ty<'tcx>,
}

#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub enum Needs {
    MutPlace,
    None,
}

impl Needs {
    fn maybe_mut_place(m: hir::Mutability) -> Self {
        match m {
            hir::Mutability::Mut => Needs::MutPlace,
            hir::Mutability::Not => Needs::None,
        }
    }
}

#[derive(Debug, Copy, Clone)]
pub enum PlaceOp {
    Deref,
    Index,
}

pub struct BreakableCtxt<'tcx> {
    may_break: bool,

    // this is `null` for loops where break with a value is illegal,
    // such as `while`, `for`, and `while let`
    coerce: Option<DynamicCoerceMany<'tcx>>,
}

pub struct EnclosingBreakables<'tcx> {
    stack: Vec<BreakableCtxt<'tcx>>,
    by_id: HirIdMap<usize>,
}

impl<'tcx> EnclosingBreakables<'tcx> {
    fn find_breakable(&mut self, target_id: HirId) -> &mut BreakableCtxt<'tcx> {
        self.opt_find_breakable(target_id).unwrap_or_else(|| {
            bug!("could not find enclosing breakable with id {}", target_id);
        })
    }

    fn opt_find_breakable(&mut self, target_id: HirId) -> Option<&mut BreakableCtxt<'tcx>> {
        match self.by_id.get(&target_id) {
            Some(ix) => Some(&mut self.stack[*ix]),
            None => None,
        }
    }
}

fn report_unexpected_variant_res(
    tcx: TyCtxt<'_>,
    res: Res,
    qpath: &hir::QPath<'_>,
    span: Span,
    err_code: ErrCode,
    expected: &str,
) -> ErrorGuaranteed {
    let res_descr = match res {
        Res::Def(DefKind::Variant, _) => "struct variant",
        _ => res.descr(),
    };
    let path_str = rustc_hir_pretty::qpath_to_string(&tcx, qpath);
    let err = tcx
        .dcx()
        .struct_span_err(span, format!("expected {expected}, found {res_descr} `{path_str}`"))
        .with_code(err_code);
    match res {
        Res::Def(DefKind::Fn | DefKind::AssocFn, _) if err_code == E0164 => {
            let patterns_url = "https://doc.rust-lang.org/book/ch18-00-patterns.html";
            err.with_span_label(span, "`fn` calls are not allowed in patterns")
                .with_help(format!("for more information, visit {patterns_url}"))
        }
        _ => err.with_span_label(span, format!("not a {expected}")),
    }
    .emit()
}

/// Controls whether the arguments are tupled. This is used for the call
/// operator.
///
/// Tupling means that all call-side arguments are packed into a tuple and
/// passed as a single parameter. For example, if tupling is enabled, this
/// function:
/// ```
/// fn f(x: (isize, isize)) {}
/// ```
/// Can be called as:
/// ```ignore UNSOLVED (can this be done in user code?)
/// # fn f(x: (isize, isize)) {}
/// f(1, 2);
/// ```
/// Instead of:
/// ```
/// # fn f(x: (isize, isize)) {}
/// f((1, 2));
/// ```
#[derive(Copy, Clone, Eq, PartialEq)]
enum TupleArgumentsFlag {
    DontTupleArguments,
    TupleArguments,
}

fn fatally_break_rust(tcx: TyCtxt<'_>, span: Span) -> ! {
    let dcx = tcx.dcx();
    let mut diag = dcx.struct_span_bug(
        span,
        "It looks like you're trying to break rust; would you like some ICE?",
    );
    diag.note("the compiler expectedly panicked. this is a feature.");
    diag.note(
        "we would appreciate a joke overview: \
         https://github.com/rust-lang/rust/issues/43162#issuecomment-320764675",
    );
    diag.note(format!("rustc {} running on {}", tcx.sess.cfg_version, config::host_triple(),));
    if let Some((flags, excluded_cargo_defaults)) = rustc_session::utils::extra_compiler_flags() {
        diag.note(format!("compiler flags: {}", flags.join(" ")));
        if excluded_cargo_defaults {
            diag.note("some of the compiler flags provided by cargo are hidden");
        }
    }
    diag.emit()
}

pub fn provide(providers: &mut Providers) {
    method::provide(providers);
    *providers = Providers { typeck, diagnostic_only_typeck, used_trait_imports, ..*providers };
}
