Rollup merge of #142401 - oli-obk:pattern-mango, r=petrochenkov

Add proper name mangling for pattern types

requires adding demangler support first https://github.com/rust-lang/rustc-demangle/pull/81

needed for https://github.com/rust-lang/rust/pull/136006#discussion_r2139792593 as otherwise we will have symbol collisions

3 files changed, 36 insertions, 10 deletions

diff --git a/compiler/rustc_symbol_mangling/src/v0.rs b/compiler/rustc_symbol_mangling/src/v0.rs
index 9fa7e2f1003..d24924b424a 100644
--- a/compiler/rustc_symbol_mangling/src/v0.rs
+++ b/compiler/rustc_symbol_mangling/src/v0.rs
@@ -262,15 +262,16 @@ impl<'tcx> V0SymbolMangler<'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");
             }
         })
     }
@@ -498,12 +499,9 @@ impl<'tcx> Printer<'tcx> for V0SymbolMangler<'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) => {
diff --git a/src/doc/rustc/src/symbol-mangling/v0.md b/src/doc/rustc/src/symbol-mangling/v0.md
index 109942518fc..2bcc453a532 100644
--- a/src/doc/rustc/src/symbol-mangling/v0.md
+++ b/src/doc/rustc/src/symbol-mangling/v0.md
@@ -710,6 +710,7 @@ A *placeholder* may occur in circumstances where a type or const value is not re
 [mut-ptr-type]: #mut-ptr-type
 [fn-type]: #fn-type
 [dyn-trait-type]: #dyn-trait-type
+[pattern-type]: #pattern-type
 
 > type → \
 > &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; *[basic-type]* \
@@ -722,6 +723,7 @@ A *placeholder* may occur in circumstances where a type or const value is not re
 > &nbsp;&nbsp; | *[mut-ptr-type]* \
 > &nbsp;&nbsp; | *[fn-type]* \
 > &nbsp;&nbsp; | *[dyn-trait-type]* \
+> &nbsp;&nbsp; | *[pattern-type]* \
 > &nbsp;&nbsp; | *[path]* \
 > &nbsp;&nbsp; | *[backref]*
 
@@ -830,6 +832,23 @@ Remaining primitives are encoded as a crate production, e.g. `C4f128`.
 [fn-sig]: #fn-sig
 [abi]: #abi
 
+* `W` — A [pattern-type][pattern-tpye] `u32 is 0..100`.
+  > <span id="pattern-type">pattern-type</span> → `W` *[pattern-kind]*
+  >
+  > <span id="pattern-kind">pattern-kind</span> → \
+  > &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; *[range-pattern-kind]* \
+  > &nbsp;&nbsp; *[or-pattern-kind]*
+  >
+  > <span id="range-pattern-kind">range-pattern-kind</span> → `R` *[const]* *[const]*
+  >
+  > <span id="or-pattern-kind">or-pattern-kind</span> → `O` *[pattern-kind]* `E`
+
+  While or patterns can be nested in theory, in practice this does not happen and they are instead flattened.
+
+  Range patterns have a start and end constant that are both included in the range.
+  The end must be larger than the start (there can be no wraparound). To emulate wraparound,
+  you need to use an or pattern of the two ranges to the upper limit and from the lower limit.
+
 * `D` — A [trait object][reference-trait-object] `dyn Trait<Assoc=X> + Send + 'a`.
 
   > <span id="dyn-trait-type">dyn-trait-type</span> → `D` *[dyn-bounds]* *[lifetime]*
@@ -1139,6 +1158,7 @@ The following is a summary of all of the productions of the symbol grammar.
 > &nbsp;&nbsp; | *[mut-ptr-type]* \
 > &nbsp;&nbsp; | *[fn-type]* \
 > &nbsp;&nbsp; | *[dyn-trait-type]* \
+> &nbsp;&nbsp; | *[pattern-type]* \
 > &nbsp;&nbsp; | *[path]* \
 > &nbsp;&nbsp; | *[backref]*
 >
@@ -1152,6 +1172,14 @@ The following is a summary of all of the productions of the symbol grammar.
 > [mut-ptr-type] → `O` *[type]* \
 > [fn-type] → `F` *[fn-sig]* \
 > [dyn-trait-type] → `D` *[dyn-bounds]* *[lifetime]*
+> [pattern-type] → `W` *[pattern-kind]*
+>
+> [pattern-kind] → \
+> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; *[range-pattern-kind]* \
+> &nbsp;&nbsp; *[or-pattern-kind]*
+>
+> [range-pattern-kind] -> `R` *[const]* *[const]* \
+> [or-pattern-kind] -> `O` *[pattern-kind]* `E` \
 >
 > [namespace] → *[lower]* | *[upper]*
 >
diff --git a/tests/codegen-llvm/pattern_type_symbols.rs b/tests/codegen-llvm/pattern_type_symbols.rs
index e86a9ef27de..a90262ff12d 100644
--- a/tests/codegen-llvm/pattern_type_symbols.rs
+++ b/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>();
 }