use hir::def_id::LocalDefId;
use hir::{ConstContext, LangItem};
use rustc_errors::{error_code, DiagnosticBuilder, ErrorGuaranteed};
use rustc_hir as hir;
use rustc_hir::def_id::DefId;
use rustc_infer::infer::TyCtxtInferExt;
use rustc_infer::traits::{ImplSource, Obligation, ObligationCause};
use rustc_middle::mir::{self, CallSource};
use rustc_middle::ty::print::with_no_trimmed_paths;
use rustc_middle::ty::TraitRef;
use rustc_middle::ty::{suggest_constraining_type_param, Adt, Closure, FnDef, FnPtr, Param, Ty};
use rustc_middle::ty::{GenericArgKind, GenericArgsRef};
use rustc_middle::util::{call_kind, CallDesugaringKind, CallKind};
use rustc_session::parse::feature_err;
use rustc_span::symbol::sym;
use rustc_span::{BytePos, Pos, Span, Symbol};
use rustc_trait_selection::traits::SelectionContext;
use super::ConstCx;
use crate::errors;
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum Status {
Allowed,
Unstable(Symbol),
Forbidden,
}
#[derive(Clone, Copy)]
pub enum DiagnosticImportance {
Primary,
Secondary,
}
pub trait NonConstOp<'tcx>: std::fmt::Debug {
fn status_in_item(&self, _ccx: &ConstCx<'_, 'tcx>) -> Status {
Status::Forbidden
}
fn importance(&self) -> DiagnosticImportance {
DiagnosticImportance::Primary
}
fn build_error(
&self,
ccx: &ConstCx<'_, 'tcx>,
span: Span,
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed>;
}
#[derive(Debug)]
pub struct FloatingPointOp;
impl<'tcx> NonConstOp<'tcx> for FloatingPointOp {
fn status_in_item(&self, ccx: &ConstCx<'_, 'tcx>) -> Status {
if ccx.const_kind() == hir::ConstContext::ConstFn {
Status::Unstable(sym::const_fn_floating_point_arithmetic)
} else {
Status::Allowed
}
}
fn build_error(
&self,
ccx: &ConstCx<'_, 'tcx>,
span: Span,
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
feature_err(
&ccx.tcx.sess.parse_sess,
sym::const_fn_floating_point_arithmetic,
span,
format!("floating point arithmetic is not allowed in {}s", ccx.const_kind()),
)
}
}
#[derive(Debug)]
pub struct FnCallIndirect;
impl<'tcx> NonConstOp<'tcx> for FnCallIndirect {
fn build_error(
&self,
ccx: &ConstCx<'_, 'tcx>,
span: Span,
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
ccx.tcx.sess.create_err(errors::UnallowedFnPointerCall { span, kind: ccx.const_kind() })
}
}
#[derive(Debug, Clone, Copy)]
pub struct FnCallNonConst<'tcx> {
pub caller: LocalDefId,
pub callee: DefId,
pub args: GenericArgsRef<'tcx>,
pub span: Span,
pub call_source: CallSource,
pub feature: Option<Symbol>,
}
impl<'tcx> NonConstOp<'tcx> for FnCallNonConst<'tcx> {
fn build_error(
&self,
ccx: &ConstCx<'_, 'tcx>,
_: Span,
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
let FnCallNonConst { caller, callee, args, span, call_source, feature } = *self;
let ConstCx { tcx, param_env, .. } = *ccx;
let diag_trait = |err, self_ty: Ty<'_>, trait_id| {
let trait_ref = TraitRef::from_method(tcx, trait_id, args);
match self_ty.kind() {
Param(param_ty) => {
debug!(?param_ty);
let caller_hir_id = tcx.hir().local_def_id_to_hir_id(caller);
if let Some(generics) = tcx.hir().get(caller_hir_id).generics() {
let constraint = with_no_trimmed_paths!(format!(
"~const {}",
trait_ref.print_only_trait_path()
));
suggest_constraining_type_param(
tcx,
generics,
err,
¶m_ty.name.as_str(),
&constraint,
None,
None,
);
}
}
Adt(..) => {
let obligation =
Obligation::new(tcx, ObligationCause::dummy(), param_env, trait_ref);
let infcx = tcx.infer_ctxt().build();
let mut selcx = SelectionContext::new(&infcx);
let implsrc = selcx.select(&obligation);
if let Ok(Some(ImplSource::UserDefined(data))) = implsrc {
if !tcx.is_const_trait_impl_raw(data.impl_def_id) {
let span = tcx.def_span(data.impl_def_id);
err.subdiagnostic(errors::NonConstImplNote { span });
}
}
}
_ => {}
}
};
let call_kind =
call_kind(tcx, ccx.param_env, callee, args, span, call_source.from_hir_call(), None);
debug!(?call_kind);
let mut err = match call_kind {
CallKind::Normal { desugaring: Some((kind, self_ty)), .. } => {
macro_rules! error {
($err:ident) => {
tcx.sess.create_err(errors::$err {
span,
ty: self_ty,
kind: ccx.const_kind(),
})
};
}
let mut err = match kind {
CallDesugaringKind::ForLoopIntoIter => {
error!(NonConstForLoopIntoIter)
}
CallDesugaringKind::QuestionBranch => {
error!(NonConstQuestionBranch)
}
CallDesugaringKind::QuestionFromResidual => {
error!(NonConstQuestionFromResidual)
}
CallDesugaringKind::TryBlockFromOutput => {
error!(NonConstTryBlockFromOutput)
}
CallDesugaringKind::Await => {
error!(NonConstAwait)
}
};
diag_trait(&mut err, self_ty, kind.trait_def_id(tcx));
err
}
CallKind::FnCall { fn_trait_id, self_ty } => {
let note = match self_ty.kind() {
FnDef(def_id, ..) => {
let span = tcx.def_span(*def_id);
if ccx.tcx.is_const_fn_raw(*def_id) {
span_bug!(span, "calling const FnDef errored when it shouldn't");
}
Some(errors::NonConstClosureNote::FnDef { span })
}
FnPtr(..) => Some(errors::NonConstClosureNote::FnPtr),
Closure(..) => Some(errors::NonConstClosureNote::Closure),
_ => None,
};
let mut err = tcx.sess.create_err(errors::NonConstClosure {
span,
kind: ccx.const_kind(),
note,
});
diag_trait(&mut err, self_ty, fn_trait_id);
err
}
CallKind::Operator { trait_id, self_ty, .. } => {
let mut err = if let CallSource::MatchCmp = call_source {
tcx.sess.create_err(errors::NonConstMatchEq {
span,
kind: ccx.const_kind(),
ty: self_ty,
})
} else {
let mut sugg = None;
if Some(trait_id) == ccx.tcx.lang_items().eq_trait() {
match (args[0].unpack(), args[1].unpack()) {
(GenericArgKind::Type(self_ty), GenericArgKind::Type(rhs_ty))
if self_ty == rhs_ty
&& self_ty.is_ref()
&& self_ty.peel_refs().is_primitive() =>
{
let mut num_refs = 0;
let mut tmp_ty = self_ty;
while let rustc_middle::ty::Ref(_, inner_ty, _) = tmp_ty.kind() {
num_refs += 1;
tmp_ty = *inner_ty;
}
let deref = "*".repeat(num_refs);
if let Ok(call_str) =
ccx.tcx.sess.source_map().span_to_snippet(span)
{
if let Some(eq_idx) = call_str.find("==") {
if let Some(rhs_idx) = call_str[(eq_idx + 2)..]
.find(|c: char| !c.is_whitespace())
{
let rhs_pos = span.lo()
+ BytePos::from_usize(eq_idx + 2 + rhs_idx);
let rhs_span = span.with_lo(rhs_pos).with_hi(rhs_pos);
sugg = Some(errors::ConsiderDereferencing {
deref,
span: span.shrink_to_lo(),
rhs_span,
});
}
}
}
}
_ => {}
}
}
tcx.sess.create_err(errors::NonConstOperator {
span,
kind: ccx.const_kind(),
sugg,
})
};
diag_trait(&mut err, self_ty, trait_id);
err
}
CallKind::DerefCoercion { deref_target, deref_target_ty, self_ty } => {
let target = if tcx.sess.source_map().is_span_accessible(deref_target) {
Some(deref_target)
} else {
None
};
let mut err = tcx.sess.create_err(errors::NonConstDerefCoercion {
span,
ty: self_ty,
kind: ccx.const_kind(),
target_ty: deref_target_ty,
deref_target: target,
});
diag_trait(&mut err, self_ty, tcx.require_lang_item(LangItem::Deref, Some(span)));
err
}
_ if tcx.opt_parent(callee) == tcx.get_diagnostic_item(sym::ArgumentMethods) => ccx
.tcx
.sess
.create_err(errors::NonConstFmtMacroCall { span, kind: ccx.const_kind() }),
_ => ccx.tcx.sess.create_err(errors::NonConstFnCall {
span,
def_path_str: ccx.tcx.def_path_str_with_args(callee, args),
kind: ccx.const_kind(),
}),
};
err.note(format!(
"calls in {}s are limited to constant functions, \
tuple structs and tuple variants",
ccx.const_kind(),
));
if let Some(feature) = feature && ccx.tcx.sess.is_nightly_build() {
err.help(format!(
"add `#![feature({feature})]` to the crate attributes to enable",
));
}
if let ConstContext::Static(_) = ccx.const_kind() {
err.note("consider wrapping this expression in `Lazy::new(|| ...)` from the `once_cell` crate: https://crates.io/crates/once_cell");
}
err
}
}
#[derive(Debug)]
pub struct FnCallUnstable(pub DefId, pub Option<Symbol>);
impl<'tcx> NonConstOp<'tcx> for FnCallUnstable {
fn build_error(
&self,
ccx: &ConstCx<'_, 'tcx>,
span: Span,
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
let FnCallUnstable(def_id, feature) = *self;
let mut err = ccx
.tcx
.sess
.create_err(errors::UnstableConstFn { span, def_path: ccx.tcx.def_path_str(def_id) });
if ccx.is_const_stable_const_fn() {
err.help("const-stable functions can only call other const-stable functions");
} else if ccx.tcx.sess.is_nightly_build() {
if let Some(feature) = feature {
err.help(format!("add `#![feature({feature})]` to the crate attributes to enable"));
}
}
err
}
}
#[derive(Debug)]
pub struct Generator(pub hir::GeneratorKind);
impl<'tcx> NonConstOp<'tcx> for Generator {
fn status_in_item(&self, _: &ConstCx<'_, 'tcx>) -> Status {
if let hir::GeneratorKind::Async(hir::AsyncGeneratorKind::Block) = self.0 {
Status::Unstable(sym::const_async_blocks)
} else {
Status::Forbidden
}
}
fn build_error(
&self,
ccx: &ConstCx<'_, 'tcx>,
span: Span,
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
let msg = format!("{}s are not allowed in {}s", self.0.descr(), ccx.const_kind());
if let hir::GeneratorKind::Async(hir::AsyncGeneratorKind::Block) = self.0 {
ccx.tcx.sess.create_feature_err(
errors::UnallowedOpInConstContext { span, msg },
sym::const_async_blocks,
)
} else {
ccx.tcx.sess.create_err(errors::UnallowedOpInConstContext { span, msg })
}
}
}
#[derive(Debug)]
pub struct HeapAllocation;
impl<'tcx> NonConstOp<'tcx> for HeapAllocation {
fn build_error(
&self,
ccx: &ConstCx<'_, 'tcx>,
span: Span,
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
ccx.tcx.sess.create_err(errors::UnallowedHeapAllocations {
span,
kind: ccx.const_kind(),
teach: ccx.tcx.sess.teach(&error_code!(E0010)).then_some(()),
})
}
}
#[derive(Debug)]
pub struct InlineAsm;
impl<'tcx> NonConstOp<'tcx> for InlineAsm {
fn build_error(
&self,
ccx: &ConstCx<'_, 'tcx>,
span: Span,
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
ccx.tcx.sess.create_err(errors::UnallowedInlineAsm { span, kind: ccx.const_kind() })
}
}
#[derive(Debug)]
pub struct LiveDrop<'tcx> {
pub dropped_at: Option<Span>,
pub dropped_ty: Ty<'tcx>,
}
impl<'tcx> NonConstOp<'tcx> for LiveDrop<'tcx> {
fn build_error(
&self,
ccx: &ConstCx<'_, 'tcx>,
span: Span,
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
ccx.tcx.sess.create_err(errors::LiveDrop {
span,
dropped_ty: self.dropped_ty,
kind: ccx.const_kind(),
dropped_at: self.dropped_at,
})
}
}
#[derive(Debug)]
pub struct TransientCellBorrow;
impl<'tcx> NonConstOp<'tcx> for TransientCellBorrow {
fn status_in_item(&self, _: &ConstCx<'_, 'tcx>) -> Status {
Status::Unstable(sym::const_refs_to_cell)
}
fn importance(&self) -> DiagnosticImportance {
DiagnosticImportance::Secondary
}
fn build_error(
&self,
ccx: &ConstCx<'_, 'tcx>,
span: Span,
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
ccx.tcx
.sess
.create_feature_err(errors::InteriorMutabilityBorrow { span }, sym::const_refs_to_cell)
}
}
#[derive(Debug)]
pub struct CellBorrow;
impl<'tcx> NonConstOp<'tcx> for CellBorrow {
fn build_error(
&self,
ccx: &ConstCx<'_, 'tcx>,
span: Span,
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
if let hir::ConstContext::Static(_) = ccx.const_kind() {
ccx.tcx.sess.create_err(errors::InteriorMutableDataRefer {
span,
opt_help: Some(()),
kind: ccx.const_kind(),
teach: ccx.tcx.sess.teach(&error_code!(E0492)).then_some(()),
})
} else {
ccx.tcx.sess.create_err(errors::InteriorMutableDataRefer {
span,
opt_help: None,
kind: ccx.const_kind(),
teach: ccx.tcx.sess.teach(&error_code!(E0492)).then_some(()),
})
}
}
}
#[derive(Debug)]
pub struct MutBorrow(pub hir::BorrowKind);
impl<'tcx> NonConstOp<'tcx> for MutBorrow {
fn status_in_item(&self, _ccx: &ConstCx<'_, 'tcx>) -> Status {
Status::Forbidden
}
fn importance(&self) -> DiagnosticImportance {
DiagnosticImportance::Secondary
}
fn build_error(
&self,
ccx: &ConstCx<'_, 'tcx>,
span: Span,
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
match self.0 {
hir::BorrowKind::Raw => ccx.tcx.sess.create_err(errors::UnallowedMutableRefsRaw {
span,
kind: ccx.const_kind(),
teach: ccx.tcx.sess.teach(&error_code!(E0764)).then_some(()),
}),
hir::BorrowKind::Ref => ccx.tcx.sess.create_err(errors::UnallowedMutableRefs {
span,
kind: ccx.const_kind(),
teach: ccx.tcx.sess.teach(&error_code!(E0764)).then_some(()),
}),
}
}
}
#[derive(Debug)]
pub struct TransientMutBorrow(pub hir::BorrowKind);
impl<'tcx> NonConstOp<'tcx> for TransientMutBorrow {
fn status_in_item(&self, _: &ConstCx<'_, 'tcx>) -> Status {
Status::Unstable(sym::const_mut_refs)
}
fn build_error(
&self,
ccx: &ConstCx<'_, 'tcx>,
span: Span,
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
let kind = ccx.const_kind();
match self.0 {
hir::BorrowKind::Raw => ccx.tcx.sess.create_feature_err(
errors::TransientMutBorrowErrRaw { span, kind },
sym::const_mut_refs,
),
hir::BorrowKind::Ref => ccx.tcx.sess.create_feature_err(
errors::TransientMutBorrowErr { span, kind },
sym::const_mut_refs,
),
}
}
}
#[derive(Debug)]
pub struct MutDeref;
impl<'tcx> NonConstOp<'tcx> for MutDeref {
fn status_in_item(&self, _: &ConstCx<'_, 'tcx>) -> Status {
Status::Unstable(sym::const_mut_refs)
}
fn importance(&self) -> DiagnosticImportance {
DiagnosticImportance::Secondary
}
fn build_error(
&self,
ccx: &ConstCx<'_, 'tcx>,
span: Span,
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
ccx.tcx.sess.create_feature_err(
errors::MutDerefErr { span, kind: ccx.const_kind() },
sym::const_mut_refs,
)
}
}
#[derive(Debug)]
pub struct PanicNonStr;
impl<'tcx> NonConstOp<'tcx> for PanicNonStr {
fn build_error(
&self,
ccx: &ConstCx<'_, 'tcx>,
span: Span,
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
ccx.tcx.sess.create_err(errors::PanicNonStrErr { span })
}
}
#[derive(Debug)]
pub struct RawPtrComparison;
impl<'tcx> NonConstOp<'tcx> for RawPtrComparison {
fn build_error(
&self,
ccx: &ConstCx<'_, 'tcx>,
span: Span,
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
ccx.tcx.sess.create_err(errors::RawPtrComparisonErr { span })
}
}
#[derive(Debug)]
pub struct RawMutPtrDeref;
impl<'tcx> NonConstOp<'tcx> for RawMutPtrDeref {
fn status_in_item(&self, _: &ConstCx<'_, '_>) -> Status {
Status::Unstable(sym::const_mut_refs)
}
fn build_error(
&self,
ccx: &ConstCx<'_, 'tcx>,
span: Span,
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
feature_err(
&ccx.tcx.sess.parse_sess,
sym::const_mut_refs,
span,
format!("dereferencing raw mutable pointers in {}s is unstable", ccx.const_kind(),),
)
}
}
#[derive(Debug)]
pub struct RawPtrToIntCast;
impl<'tcx> NonConstOp<'tcx> for RawPtrToIntCast {
fn build_error(
&self,
ccx: &ConstCx<'_, 'tcx>,
span: Span,
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
ccx.tcx.sess.create_err(errors::RawPtrToIntErr { span })
}
}
#[derive(Debug)]
pub struct StaticAccess;
impl<'tcx> NonConstOp<'tcx> for StaticAccess {
fn status_in_item(&self, ccx: &ConstCx<'_, 'tcx>) -> Status {
if let hir::ConstContext::Static(_) = ccx.const_kind() {
Status::Allowed
} else {
Status::Forbidden
}
}
fn build_error(
&self,
ccx: &ConstCx<'_, 'tcx>,
span: Span,
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
ccx.tcx.sess.create_err(errors::StaticAccessErr {
span,
kind: ccx.const_kind(),
teach: ccx.tcx.sess.teach(&error_code!(E0013)).then_some(()),
})
}
}
#[derive(Debug)]
pub struct ThreadLocalAccess;
impl<'tcx> NonConstOp<'tcx> for ThreadLocalAccess {
fn build_error(
&self,
ccx: &ConstCx<'_, 'tcx>,
span: Span,
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
ccx.tcx.sess.create_err(errors::NonConstOpErr { span })
}
}
pub mod ty {
use super::*;
#[derive(Debug)]
pub struct MutRef(pub mir::LocalKind);
impl<'tcx> NonConstOp<'tcx> for MutRef {
fn status_in_item(&self, _ccx: &ConstCx<'_, 'tcx>) -> Status {
Status::Unstable(sym::const_mut_refs)
}
fn importance(&self) -> DiagnosticImportance {
match self.0 {
mir::LocalKind::Temp => DiagnosticImportance::Secondary,
mir::LocalKind::ReturnPointer | mir::LocalKind::Arg => {
DiagnosticImportance::Primary
}
}
}
fn build_error(
&self,
ccx: &ConstCx<'_, 'tcx>,
span: Span,
) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
feature_err(
&ccx.tcx.sess.parse_sess,
sym::const_mut_refs,
span,
format!("mutable references are not allowed in {}s", ccx.const_kind()),
)
}
}
}