[const-prop] Run `x.py fmt`

[rust.git] / src / librustc_mir / const_eval.rs

diff --git a/src/librustc_mir/const_eval.rs b/src/librustc_mir/const_eval.rs
index 7b2ce7f9ac7be9f3f4d8d318bbf1436aaf59fea0..aad0e1629359a8523895b2e7f2e9a67c9df8d674 100644 (file)
--- a/src/librustc_mir/const_eval.rs
+++ b/src/librustc_mir/const_eval.rs
@@ -5,7 +5,7 @@
 use rustc::ty::{self, TyCtxt};
 use rustc_span::{source_map::DUMMY_SP, symbol::Symbol};
 
-use crate::interpret::{intern_const_alloc_recursive, ConstValue, InterpCx};
+use crate::interpret::{intern_const_alloc_recursive, ConstValue, InternKind, InterpCx};
 
 mod error;
 mod eval_queries;
@@ -52,7 +52,7 @@ pub(crate) fn const_caller_location<'tcx>(
 
     let loc_ty = tcx.caller_location_ty();
     let loc_place = ecx.alloc_caller_location(file, line, col);
-    intern_const_alloc_recursive(&mut ecx, None, loc_place).unwrap();
+    intern_const_alloc_recursive(&mut ecx, InternKind::Constant, loc_place, false).unwrap();
     let loc_const = ty::Const {
         ty: loc_ty,
         val: ty::ConstKind::Value(ConstValue::Scalar(loc_place.ptr.into())),
@@ -61,15 +61,32 @@ pub(crate) fn const_caller_location<'tcx>(
     tcx.mk_const(loc_const)
 }
 
-// this function uses `unwrap` copiously, because an already validated constant must have valid
-// fields and can thus never fail outside of compiler bugs
-pub(crate) fn const_variant_index<'tcx>(
+// this function uses `unwrap` copiously, because an already validated constant
+// must have valid fields and can thus never fail outside of compiler bugs
+pub(crate) fn destructure_const<'tcx>(
     tcx: TyCtxt<'tcx>,
     param_env: ty::ParamEnv<'tcx>,
     val: &'tcx ty::Const<'tcx>,
-) -> VariantIdx {
-    trace!("const_variant_index: {:?}", val);
+) -> mir::DestructuredConst<'tcx> {
+    trace!("destructure_const: {:?}", val);
     let ecx = mk_eval_cx(tcx, DUMMY_SP, param_env, false);
     let op = ecx.eval_const_to_op(val, None).unwrap();
-    ecx.read_discriminant(op).unwrap().1
+
+    let variant = ecx.read_discriminant(op).unwrap().1;
+
+    let field_count = match val.ty.kind {
+        ty::Array(_, len) => len.eval_usize(tcx, param_env),
+        ty::Adt(def, _) => def.variants[variant].fields.len() as u64,
+        ty::Tuple(substs) => substs.len() as u64,
+        _ => bug!("cannot destructure constant {:?}", val),
+    };
+
+    let down = ecx.operand_downcast(op, variant).unwrap();
+    let fields_iter = (0..field_count).map(|i| {
+        let field_op = ecx.operand_field(down, i).unwrap();
+        op_to_const(&ecx, field_op)
+    });
+    let fields = tcx.arena.alloc_from_iter(fields_iter);
+
+    mir::DestructuredConst { variant, fields }
 }