Try to evaluate constants in legacy mangling

Author: oli-obk

compiler/rustc_symbol_mangling/src/legacy.rs

@@ -2,12 +2,13 @@ use std::fmt::{self, Write};
 use std::mem::{self, discriminant};
 
 use rustc_data_structures::stable_hasher::{Hash64, HashStable, StableHasher};
-use rustc_hir::def_id::CrateNum;
+use rustc_hir::def_id::{CrateNum, DefId};
 use rustc_hir::definitions::{DefPathData, DisambiguatedDefPathData};
 use rustc_middle::bug;
 use rustc_middle::ty::print::{PrettyPrinter, Print, PrintError, Printer};
 use rustc_middle::ty::{
     self, GenericArg, GenericArgKind, Instance, ReifyReason, Ty, TyCtxt, TypeVisitableExt,
+    TypingEnv,
 };
 use tracing::debug;
 
@@ -54,7 +55,12 @@ pub(super) fn mangle<'tcx>(
 
     let hash = get_symbol_hash(tcx, instance, instance_ty, instantiating_crate);
 
-    let mut printer = SymbolPrinter { tcx, path: SymbolPath::new(), keep_within_component: false };
+    let mut printer = SymbolPrinter {
+        tcx,
+        path: SymbolPath::new(),
+        keep_within_component: false,
+        instance_def_id: ty_def_id,
+    };
     printer
         .print_def_path(
             def_id,
@@ -204,6 +210,10 @@ struct SymbolPrinter<'tcx> {
     tcx: TyCtxt<'tcx>,
     path: SymbolPath,
 
+    // The item currently being printed. Used to obtain a `TypingEnv`
+    // for evaluating constants in the signature.
+    instance_def_id: DefId,
+
     // When `true`, `finalize_pending_component` isn't used.
     // This is needed when recursing into `path_qualified`,
     // or `path_generic_args`, as any nested paths are
@@ -239,6 +249,13 @@ impl<'tcx> Printer<'tcx> for SymbolPrinter<'tcx> {
                 self.write_str("[")?;
                 self.print_type(ty)?;
                 self.write_str("; ")?;
+                let size = self
+                    .tcx
+                    .try_normalize_erasing_regions(
+                        TypingEnv::non_body_analysis(self.tcx, self.instance_def_id),
+                        size,
+                    )
+                    .unwrap_or(size);
                 if let Some(size) = size.try_to_target_usize(self.tcx()) {
                     write!(self, "{size}")?
                 } else if let ty::ConstKind::Param(param) = size.kind() {
@@ -272,6 +289,13 @@ impl<'tcx> Printer<'tcx> for SymbolPrinter<'tcx> {
     }
 
     fn print_const(&mut self, ct: ty::Const<'tcx>) -> Result<(), PrintError> {
+        let ct = self
+            .tcx
+            .try_normalize_erasing_regions(
+                TypingEnv::non_body_analysis(self.tcx, self.instance_def_id),
+                ct,
+            )
+            .unwrap_or(ct);
         // only print integers
         match ct.kind() {
             ty::ConstKind::Value(ty, ty::ValTree::Leaf(scalar)) if ty.is_integral() => {

tests/ui/symbol-names/types.legacy.stderr

@@ -502,19 +502,19 @@ error: demangling-alt(a::b::Type<[T; N]>)
 LL |     #[rustc_symbol_name]
    |     ^^^^^^^^^^^^^^^^^^^^
 
-error: symbol-name(_ZN1a1b35Type$LT$$u5b$u8$u3b$$u20$_$u5d$$GT$17h[HASH]E)
+error: symbol-name(_ZN1a1b35Type$LT$$u5b$u8$u3b$$u20$0$u5d$$GT$17h[HASH]E)
   --> $DIR/types.rs:272:5
    |
 LL |     #[rustc_symbol_name]
    |     ^^^^^^^^^^^^^^^^^^^^
 
-error: demangling(a::b::Type<[u8; _]>::h[HASH])
+error: demangling(a::b::Type<[u8; 0]>::h[HASH])
   --> $DIR/types.rs:272:5
    |
 LL |     #[rustc_symbol_name]
    |     ^^^^^^^^^^^^^^^^^^^^
 
-error: demangling-alt(a::b::Type<[u8; _]>)
+error: demangling-alt(a::b::Type<[u8; 0]>)
   --> $DIR/types.rs:272:5
    |
 LL |     #[rustc_symbol_name]

tests/ui/symbol-names/types.rs

@@ -270,9 +270,9 @@ pub fn b() {
     const ZERO: usize = 0;
 
     #[rustc_symbol_name]
-    //[legacy,verbose-legacy]~^ ERROR symbol-name(_ZN1a1b35Type$LT$$u5b$u8$u3b$$u20$_$u5d$$GT$
-    //[legacy,verbose-legacy]~| ERROR demangling(a::b::Type<[u8; _]>::
-    //[legacy,verbose-legacy]~| ERROR demangling-alt(a::b::Type<[u8; _]>)
+    //[legacy,verbose-legacy]~^ ERROR symbol-name(_ZN1a1b35Type$LT$$u5b$u8$u3b$$u20$0$u5d$$GT$
+    //[legacy,verbose-legacy]~| ERROR demangling(a::b::Type<[u8; 0]>::
+    //[legacy,verbose-legacy]~| ERROR demangling-alt(a::b::Type<[u8; 0]>)
     //[v0]~^^^^ ERROR symbol-name(_RMsq_NvCsCRATE_HASH_1a1bINtB<REF>_4TypeAhj0_E)
     //[v0]~| ERROR ::b::Type<[u8; 0usize]>>)
     //[v0]~| ERROR demangling-alt(<a::b::Type<[u8; 0]>>)

tests/ui/symbol-names/types.verbose-legacy.stderr

@@ -502,19 +502,19 @@ error: demangling-alt(a::b::Type<[T; N]>)
 LL |     #[rustc_symbol_name]
    |     ^^^^^^^^^^^^^^^^^^^^
 
-error: symbol-name(_ZN1a1b35Type$LT$$u5b$u8$u3b$$u20$_$u5d$$GT$17h[HASH]E)
+error: symbol-name(_ZN1a1b35Type$LT$$u5b$u8$u3b$$u20$0$u5d$$GT$17h[HASH]E)
   --> $DIR/types.rs:272:5
    |
 LL |     #[rustc_symbol_name]
    |     ^^^^^^^^^^^^^^^^^^^^
 
-error: demangling(a::b::Type<[u8; _]>::h[HASH])
+error: demangling(a::b::Type<[u8; 0]>::h[HASH])
   --> $DIR/types.rs:272:5
    |
 LL |     #[rustc_symbol_name]
    |     ^^^^^^^^^^^^^^^^^^^^
 
-error: demangling-alt(a::b::Type<[u8; _]>)
+error: demangling-alt(a::b::Type<[u8; 0]>)
   --> $DIR/types.rs:272:5
    |
 LL |     #[rustc_symbol_name]