Add pretty printer support for ConstValue without going through ty::Const

Author: oli-obk

compiler/rustc_infer/src/infer/error_reporting/mod.rs

@@ -65,6 +65,7 @@ use rustc_hir::def_id::DefId;
 use rustc_hir::lang_items::LangItem;
 use rustc_hir::{Item, ItemKind, Node};
 use rustc_middle::dep_graph::DepContext;
+use rustc_middle::mir::interpret::ConstValue;
 use rustc_middle::ty::error::TypeError;
 use rustc_middle::ty::{
     self,
@@ -524,6 +525,14 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                 Err(NonTrivialPath)
             }
 
+            fn print_const_value(
+                self,
+                _value: ConstValue<'tcx>,
+                _ty: Ty<'tcx>,
+            ) -> Result<Self::Const, Self::Error> {
+                Err(NonTrivialPath)
+            }
+
             fn path_crate(self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
                 Ok(vec![self.tcx.crate_name(cnum).to_string()])
             }

compiler/rustc_lint/src/context.rs

@@ -31,6 +31,7 @@ use rustc_hir::definitions::{DefPathData, DisambiguatedDefPathData};
 use rustc_middle::lint::LintDiagnosticBuilder;
 use rustc_middle::middle::privacy::AccessLevels;
 use rustc_middle::middle::stability;
+use rustc_middle::mir::interpret::ConstValue;
 use rustc_middle::ty::layout::{LayoutError, TyAndLayout};
 use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_middle::ty::{self, print::Printer, subst::GenericArg, Ty, TyCtxt};
@@ -943,6 +944,14 @@ impl<'tcx> LateContext<'tcx> {
                 Ok(())
             }
 
+            fn print_const_value(
+                self,
+                _val: ConstValue<'tcx>,
+                _ty: Ty<'tcx>,
+            ) -> Result<Self::Const, Self::Error> {
+                Ok(())
+            }
+
             fn path_crate(self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
                 Ok(vec![self.tcx.crate_name(cnum)])
             }

compiler/rustc_middle/src/ty/print/mod.rs

@@ -1,3 +1,4 @@
+use crate::mir::interpret::ConstValue;
 use crate::ty::subst::{GenericArg, Subst};
 use crate::ty::{self, DefIdTree, Ty, TyCtxt};
 
@@ -68,6 +69,12 @@ pub trait Printer<'tcx>: Sized {
 
     fn print_const(self, ct: &'tcx ty::Const<'tcx>) -> Result<Self::Const, Self::Error>;
 
+    fn print_const_value(
+        self,
+        val: ConstValue<'tcx>,
+        ty: Ty<'tcx>,
+    ) -> Result<Self::Const, Self::Error>;
+
     fn path_crate(self, cnum: CrateNum) -> Result<Self::Path, Self::Error>;
 
     fn path_qualified(
@@ -362,3 +369,11 @@ impl<'tcx, P: Printer<'tcx>> Print<'tcx, P> for &'tcx ty::Const<'tcx> {
         cx.print_const(self)
     }
 }
+
+impl<'tcx, P: Printer<'tcx>> Print<'tcx, P> for (ConstValue<'tcx>, Ty<'tcx>) {
+    type Output = P::Const;
+    type Error = P::Error;
+    fn print(&self, cx: P) -> Result<Self::Output, Self::Error> {
+        cx.print_const_value(self.0, self.1)
+    }
+}

compiler/rustc_middle/src/ty/print/pretty.rs

@@ -1458,6 +1458,14 @@ impl<F: fmt::Write> Printer<'tcx> for FmtPrinter<'_, 'tcx, F> {
         self.pretty_print_const(ct, true)
     }
 
+    fn print_const_value(
+        self,
+        val: ConstValue<'tcx>,
+        ty: Ty<'tcx>,
+    ) -> Result<Self::Const, Self::Error> {
+        self.pretty_print_const_value(val, ty, true)
+    }
+
     fn path_crate(mut self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
         self.empty_path = true;
         if cnum == LOCAL_CRATE {

compiler/rustc_mir/src/interpret/intrinsics/type_name.rs

@@ -1,6 +1,6 @@
 use rustc_hir::def_id::CrateNum;
 use rustc_hir::definitions::DisambiguatedDefPathData;
-use rustc_middle::mir::interpret::Allocation;
+use rustc_middle::mir::interpret::{Allocation, ConstValue};
 use rustc_middle::ty::{
     self,
     print::{PrettyPrinter, Print, Printer},
@@ -72,6 +72,14 @@ impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> {
         self.pretty_print_const(ct, false)
     }
 
+    fn print_const_value(
+        self,
+        val: ConstValue<'tcx>,
+        ty: Ty<'tcx>,
+    ) -> Result<Self::Const, Self::Error> {
+        self.pretty_print_const_value(val, ty, false)
+    }
+
     fn print_dyn_existential(
         mut self,
         predicates: &'tcx ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>>,

compiler/rustc_symbol_mangling/src/legacy.rs

@@ -253,6 +253,14 @@ impl Printer<'tcx> for SymbolPrinter<'tcx> {
         Ok(self)
     }
 
+    fn print_const_value(
+        self,
+        value: ConstValue<'tcx>,
+        ty: Ty<'tcx>,
+    ) -> Result<Self::Const, Self::Error> {
+        bug!("symbol mangling should never see MIR constants, but saw {:?}:{:?}", value, ty)
+    }
+
     fn path_crate(mut self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
         self.write_str(&self.tcx.crate_name(cnum).as_str())?;
         Ok(self)

compiler/rustc_symbol_mangling/src/v0.rs

@@ -3,6 +3,7 @@ use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_hir as hir;
 use rustc_hir::def_id::{CrateNum, DefId};
 use rustc_hir::definitions::{DefPathData, DisambiguatedDefPathData};
+use rustc_middle::mir::interpret::ConstValue;
 use rustc_middle::ty::layout::IntegerExt;
 use rustc_middle::ty::print::{Print, Printer};
 use rustc_middle::ty::subst::{GenericArg, GenericArgKind, Subst};
@@ -590,6 +591,14 @@ impl Printer<'tcx> for SymbolMangler<'tcx> {
         Ok(self)
     }
 
+    fn print_const_value(
+        self,
+        value: ConstValue<'tcx>,
+        ty: Ty<'tcx>,
+    ) -> Result<Self::Const, Self::Error> {
+        bug!("symbol mangling should never see MIR constants, but saw {:?}:{:?}", value, ty)
+    }
+
     fn path_crate(mut self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
         self.push("C");
         let stable_crate_id = self.tcx.def_path_hash(cnum.as_def_id()).stable_crate_id();