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//! Validates the MIR to ensure that invariants are upheld.
use super::{MirPass, MirSource};
use rustc_middle::mir::visit::Visitor;
use rustc_middle::{
mir::{Body, Location, Operand, Rvalue, Statement, StatementKind},
ty::{ParamEnv, TyCtxt},
};
use rustc_span::{def_id::DefId, Span, DUMMY_SP};
pub struct Validator {
/// Describes at which point in the pipeline this validation is happening.
pub when: String,
}
impl<'tcx> MirPass<'tcx> for Validator {
fn run_pass(&self, tcx: TyCtxt<'tcx>, source: MirSource<'tcx>, body: &mut Body<'tcx>) {
let def_id = source.def_id();
let param_env = tcx.param_env(def_id);
TypeChecker { when: &self.when, def_id, body, tcx, param_env }.visit_body(body);
}
}
struct TypeChecker<'a, 'tcx> {
when: &'a str,
def_id: DefId,
body: &'a Body<'tcx>,
tcx: TyCtxt<'tcx>,
param_env: ParamEnv<'tcx>,
}
impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
fn fail(&self, span: Span, msg: impl AsRef<str>) {
// We use `delay_span_bug` as we might see broken MIR when other errors have already
// occurred.
self.tcx.sess.diagnostic().delay_span_bug(
span,
&format!("broken MIR in {:?} ({}): {}", self.def_id, self.when, msg.as_ref()),
);
}
}
impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
fn visit_operand(&mut self, operand: &Operand<'tcx>, location: Location) {
// `Operand::Copy` is only supposed to be used with `Copy` types.
if let Operand::Copy(place) = operand {
let ty = place.ty(&self.body.local_decls, self.tcx).ty;
if !ty.is_copy_modulo_regions(self.tcx, self.param_env, DUMMY_SP) {
self.fail(
DUMMY_SP,
format!("`Operand::Copy` with non-`Copy` type {} at {:?}", ty, location),
);
}
}
self.super_operand(operand, location);
}
fn visit_statement(&mut self, statement: &Statement<'tcx>, location: Location) {
// The sides of an assignment must not alias. Currently this just checks whether the places
// are identical.
if let StatementKind::Assign(box (dest, rvalue)) = &statement.kind {
match rvalue {
Rvalue::Use(Operand::Copy(src) | Operand::Move(src)) => {
if dest == src {
self.fail(
DUMMY_SP,
format!(
"encountered `Assign` statement with overlapping memory at {:?}",
location
),
);
}
}
_ => {}
}
}
}
}
|
