Add proper name mangling for pattern types

Author: oli-obk

compiler/rustc_symbol_mangling/src/v0.rs

@@ -258,15 +258,16 @@ impl<'tcx> SymbolMangler<'tcx> {
     fn print_pat(&mut self, pat: ty::Pattern<'tcx>) -> Result<(), std::fmt::Error> {
         Ok(match *pat {
             ty::PatternKind::Range { start, end } => {
-                let consts = [start, end];
-                for ct in consts {
-                    Ty::new_array_with_const_len(self.tcx, self.tcx.types.unit, ct).print(self)?;
-                }
+                self.push("R");
+                self.print_const(start)?;
+                self.print_const(end)?;
             }
             ty::PatternKind::Or(patterns) => {
+                self.push("O");
                 for pat in patterns {
                     self.print_pat(pat)?;
                 }
+                self.push("E");
             }
         })
     }
@@ -494,12 +495,9 @@ impl<'tcx> Printer<'tcx> for SymbolMangler<'tcx> {
             }
 
             ty::Pat(ty, pat) => {
-                // HACK: Represent as tuple until we have something better.
-                // HACK: constants are used in arrays, even if the types don't match.
-                self.push("T");
+                self.push("W");
                 ty.print(self)?;
                 self.print_pat(pat)?;
-                self.push("E");
             }
 
             ty::Array(ty, len) => {

tests/codegen-llvm/pattern_type_symbols.rs

@@ -16,7 +16,7 @@ pub fn bar() {
     // CHECK: call pattern_type_symbols::foo::<u32>
     // CHECK: call void @_RINvC[[CRATE_IDENT:[a-zA-Z0-9]{12}]]_20pattern_type_symbols3foomEB2_
     foo::<u32>();
-    // CHECK: call pattern_type_symbols::foo::<(u32, [(); 0], [(); 999999999])>
-    // CHECK: call void @_RINvC[[CRATE_IDENT]]_20pattern_type_symbols3fooTmAum0_Aum3b9ac9ff_EEB2_
+    // CHECK: call pattern_type_symbols::foo::<u32 is 0..=999999999>
+    // CHECK: call void @_RINvC[[CRATE_IDENT]]_20pattern_type_symbols3fooWmRm0_m3b9ac9ff_EB2_
     foo::<NanoU32>();
 }