Remove lit_to_mir_constant query

Author: oli-obk

compiler/rustc_middle/src/query/mod.rs

@@ -1092,10 +1092,6 @@ rustc_queries! {
         desc { "converting literal to const" }
     }
 
-    query lit_to_mir_constant(key: LitToConstInput<'tcx>) -> Result<mir::ConstantKind<'tcx>, LitToConstError> {
-        desc { "converting literal to mir constant" }
-    }
-
     query check_match(key: LocalDefId) -> Result<(), rustc_errors::ErrorGuaranteed> {
         desc { |tcx| "match-checking `{}`", tcx.def_path_str(key) }
         cache_on_disk_if { true }

compiler/rustc_mir_build/src/build/expr/as_constant.rs

@@ -106,7 +106,7 @@ pub fn as_constant_inner<'tcx>(
 }
 
 #[instrument(skip(tcx, lit_input))]
-pub(crate) fn lit_to_mir_constant<'tcx>(
+fn lit_to_mir_constant<'tcx>(
     tcx: TyCtxt<'tcx>,
     lit_input: LitToConstInput<'tcx>,
 ) -> Result<ConstantKind<'tcx>, LitToConstError> {

compiler/rustc_mir_build/src/build/mod.rs

@@ -1,4 +1,3 @@
-pub(crate) use crate::build::expr::as_constant::lit_to_mir_constant;
 use crate::build::expr::as_place::PlaceBuilder;
 use crate::build::scope::DropKind;
 use rustc_apfloat::ieee::{Double, Single};

compiler/rustc_mir_build/src/lib.rs

@@ -32,7 +32,6 @@ fluent_messages! { "../messages.ftl" }
 pub fn provide(providers: &mut Providers) {
     providers.check_match = thir::pattern::check_match;
     providers.lit_to_const = thir::constant::lit_to_const;
-    providers.lit_to_mir_constant = build::lit_to_mir_constant;
     providers.mir_built = build::mir_built;
     providers.thir_check_unsafety = check_unsafety::thir_check_unsafety;
     providers.thir_body = thir::cx::thir_body;

compiler/rustc_mir_build/src/thir/constant.rs

@@ -48,6 +48,11 @@ pub(crate) fn lit_to_const<'tcx>(
         (ast::LitKind::Byte(n), ty::Uint(ty::UintTy::U8)) => {
             ty::ValTree::from_scalar_int((*n).into())
         }
+        (ast::LitKind::CStr(data, _), ty::Ref(_, inner_ty, _)) if matches!(inner_ty.kind(), ty::Adt(def, _) if Some(def.did()) == tcx.lang_items().c_str()) =>
+        {
+            let bytes = data as &[u8];
+            ty::ValTree::from_raw_bytes(tcx, bytes)
+        }
         (ast::LitKind::Int(n, _), ty::Uint(_)) | (ast::LitKind::Int(n, _), ty::Int(_)) => {
             let scalar_int =
                 trunc(if neg { (*n as i128).overflowing_neg().0 as u128 } else { *n })?;

compiler/rustc_mir_build/src/thir/pattern/mod.rs

@@ -20,7 +20,7 @@ use rustc_index::Idx;
 use rustc_middle::mir::interpret::{
     ConstValue, ErrorHandled, GlobalId, LitToConstError, LitToConstInput, Scalar,
 };
-use rustc_middle::mir::{self, UserTypeProjection};
+use rustc_middle::mir::{self, ConstantKind, UserTypeProjection};
 use rustc_middle::mir::{BorrowKind, Mutability};
 use rustc_middle::thir::{Ascription, BindingMode, FieldPat, LocalVarId, Pat, PatKind, PatRange};
 use rustc_middle::ty::subst::{GenericArg, SubstsRef};
@@ -646,14 +646,10 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
 
         let lit_input =
             LitToConstInput { lit: &lit.node, ty: self.typeck_results.expr_ty(expr), neg };
-        match self
-            .tcx
-            .at(expr.span)
-            .lit_to_const(lit_input)
-            .map(mir::ConstantKind::Ty)
-            .or_else(|_| self.tcx.at(expr.span).lit_to_mir_constant(lit_input))
-        {
-            Ok(constant) => self.const_to_pat(constant, expr.hir_id, lit.span, None).kind,
+        match self.tcx.at(expr.span).lit_to_const(lit_input) {
+            Ok(constant) => {
+                self.const_to_pat(ConstantKind::Ty(constant), expr.hir_id, lit.span, None).kind
+            }
             Err(LitToConstError::Reported(_)) => PatKind::Wild,
             Err(LitToConstError::TypeError) => bug!("lower_lit: had type error"),
         }