tests: add v0 structural const value demangling test.

src/test/ui/symbol-names/const-generics-structural-demangling.rs

+// build-fail
+// compile-flags: -Z symbol-mangling-version=v0 --crate-name=c
+
+// NOTE(eddyb) we need `core` for `core::option::Option`, normalize away its
+// disambiguator hash, which can/should change (including between stage{1,2}).
+// normalize-stderr-test: "Cs[0-9a-zA-Z]+_4core" -> "Cs$$HASH_4core"
+// normalize-stderr-test: "core\[[0-9a-f]+\]" -> "core[$$HASH_HEX]"
+
+#![feature(const_generics, decl_macro, rustc_attrs)]
+#![allow(incomplete_features)]
+
+pub struct RefByte<const RB: &'static u8>;
+
+#[rustc_symbol_name]
+//~^ ERROR symbol-name(_RMCsno73SFvQKx_1cINtB0_7RefByteKRh7b_E)
+//~| ERROR demangling(<c[464da6a86cb672f]::RefByte<{&123u8}>>)
+//~| ERROR demangling-alt(<c::RefByte<{&123}>>)
+impl RefByte<{&123}> {}
+
+// FIXME(eddyb) this was supposed to be `RefMutZst` with `&mut []`,
+// but that is currently not allowed in const generics.
+pub struct RefZst<const RMZ: &'static [u8; 0]>;
+
+#[rustc_symbol_name]
+//~^ ERROR symbol-name(_RMs_Csno73SFvQKx_1cINtB2_6RefZstKRAEE)
+//~| ERROR demangling(<c[464da6a86cb672f]::RefZst<{&[]}>>)
+//~| ERROR demangling-alt(<c::RefZst<{&[]}>>)
+impl RefZst<{&[]}> {}
+
+pub struct Array3Bytes<const A3B: [u8; 3]>;
+
+#[rustc_symbol_name]
+//~^ ERROR symbol-name(_RMs0_Csno73SFvQKx_1cINtB3_11Array3BytesKAh1_h2_h3_EE)
+//~| ERROR demangling(<c[464da6a86cb672f]::Array3Bytes<{[1u8, 2u8, 3u8]}>>)
+//~| ERROR demangling-alt(<c::Array3Bytes<{[1, 2, 3]}>>)
+impl Array3Bytes<{[1, 2, 3]}> {}
+
+pub struct TupleByteBool<const TBB: (u8, bool)>;
+
+#[rustc_symbol_name]
+//~^ ERROR symbol-name(_RMs1_Csno73SFvQKx_1cINtB3_13TupleByteBoolKTh1_b0_EE)
+//~| ERROR demangling(<c[464da6a86cb672f]::TupleByteBool<{(1u8, false)}>>)
+//~| ERROR demangling-alt(<c::TupleByteBool<{(1, false)}>>)
+impl TupleByteBool<{(1, false)}> {}
+
+pub struct OptionUsize<const OU: Option<usize>>;
+
+// HACK(eddyb) the full mangling is only in `.stderr` because we can normalize
+// the `core` disambiguator hash away there, but not here.
+#[rustc_symbol_name]
+//~^ ERROR symbol-name(_RMs2_Csno73SFvQKx_1cINtB3_11OptionUsizeKVNtINtNtCs
+//~| ERROR demangling(<c[464da6a86cb672f]::OptionUsize<{core[
+//~| ERROR demangling-alt(<c::OptionUsize<{core::option::Option::<usize>::None}>>)
+impl OptionUsize<{None}> {}
+
+// HACK(eddyb) the full mangling is only in `.stderr` because we can normalize
+// the `core` disambiguator hash away there, but not here.
+#[rustc_symbol_name]
+//~^ ERROR symbol-name(_RMs3_Csno73SFvQKx_1cINtB3_11OptionUsizeKVNtINtNtCs
+//~| ERROR demangling(<c[464da6a86cb672f]::OptionUsize<{core[
+//~| ERROR demangling-alt(<c::OptionUsize<{core::option::Option::<usize>::Some(0)}>>)
+impl OptionUsize<{Some(0)}> {}
+
+#[derive(PartialEq, Eq)]
+pub struct Foo {
+    s: &'static str,
+    ch: char,
+    slice: &'static [u8],
+}
+pub struct Foo_<const F: Foo>;
+
+#[rustc_symbol_name]
+//~^ ERROR symbol-name(_RMs4_Csno73SFvQKx_1cINtB3_4Foo_KVNtB3_3FooS1sRe616263_2chc78_5sliceRAh1_h2_h3_EEE)
+//~| ERROR demangling(<c[464da6a86cb672f]::Foo_<{c[464da6a86cb672f]::Foo { s: "abc", ch: 'x', slice: &[1u8, 2u8, 3u8] }}>>)
+//~| ERROR demangling-alt(<c::Foo_<{c::Foo { s: "abc", ch: 'x', slice: &[1, 2, 3] }}>>)
+impl Foo_<{Foo { s: "abc", ch: 'x', slice: &[1, 2, 3] }}> {}
+
+// NOTE(eddyb) this tests specifically the use of disambiguators in field names,
+// using macros 2.0 hygiene to create a `struct` with conflicting field names.
+macro duplicate_field_name_test($x:ident) {
+    #[derive(PartialEq, Eq)]
+    pub struct Bar {
+        $x: u8,
+        x: u16,
+    }
+    pub struct Bar_<const B: Bar>;
+
+    #[rustc_symbol_name]
+    //~^ ERROR symbol-name(_RMs9_Csno73SFvQKx_1cINtB3_4Bar_KVNtB3_3BarS1xh7b_s_1xt1000_EE)
+    //~| ERROR demangling(<c[464da6a86cb672f]::Bar_<{c[464da6a86cb672f]::Bar { x: 123u8, x: 4096u16 }}>>)
+    //~| ERROR demangling-alt(<c::Bar_<{c::Bar { x: 123, x: 4096 }}>>)
+    impl Bar_<{Bar { $x: 123, x: 4096 }}> {}
+}
+duplicate_field_name_test!(x);
+
+fn main() {}

src/test/ui/symbol-names/const-generics-structural-demangling.stderr

+error: symbol-name(_RMCsno73SFvQKx_1cINtB0_7RefByteKRh7b_E)
+  --> $DIR/const-generics-structural-demangling.rs:14:1
+   |
+LL | #[rustc_symbol_name]
+   | ^^^^^^^^^^^^^^^^^^^^
+
+error: demangling(<c[464da6a86cb672f]::RefByte<{&123u8}>>)
+  --> $DIR/const-generics-structural-demangling.rs:14:1
+   |
+LL | #[rustc_symbol_name]
+   | ^^^^^^^^^^^^^^^^^^^^
+
+error: demangling-alt(<c::RefByte<{&123}>>)
+  --> $DIR/const-generics-structural-demangling.rs:14:1
+   |
+LL | #[rustc_symbol_name]
+   | ^^^^^^^^^^^^^^^^^^^^
+
+error: symbol-name(_RMs_Csno73SFvQKx_1cINtB2_6RefZstKRAEE)
+  --> $DIR/const-generics-structural-demangling.rs:24:1
+   |
+LL | #[rustc_symbol_name]
+   | ^^^^^^^^^^^^^^^^^^^^
+
+error: demangling(<c[464da6a86cb672f]::RefZst<{&[]}>>)
+  --> $DIR/const-generics-structural-demangling.rs:24:1
+   |
+LL | #[rustc_symbol_name]
+   | ^^^^^^^^^^^^^^^^^^^^
+
+error: demangling-alt(<c::RefZst<{&[]}>>)
+  --> $DIR/const-generics-structural-demangling.rs:24:1
+   |
+LL | #[rustc_symbol_name]
+   | ^^^^^^^^^^^^^^^^^^^^
+
+error: symbol-name(_RMs0_Csno73SFvQKx_1cINtB3_11Array3BytesKAh1_h2_h3_EE)
+  --> $DIR/const-generics-structural-demangling.rs:32:1
+   |
+LL | #[rustc_symbol_name]
+   | ^^^^^^^^^^^^^^^^^^^^
+
+error: demangling(<c[464da6a86cb672f]::Array3Bytes<{[1u8, 2u8, 3u8]}>>)
+  --> $DIR/const-generics-structural-demangling.rs:32:1
+   |
+LL | #[rustc_symbol_name]
+   | ^^^^^^^^^^^^^^^^^^^^
+
+error: demangling-alt(<c::Array3Bytes<{[1, 2, 3]}>>)
+  --> $DIR/const-generics-structural-demangling.rs:32:1
+   |
+LL | #[rustc_symbol_name]
+   | ^^^^^^^^^^^^^^^^^^^^
+
+error: symbol-name(_RMs1_Csno73SFvQKx_1cINtB3_13TupleByteBoolKTh1_b0_EE)
+  --> $DIR/const-generics-structural-demangling.rs:40:1
+   |
+LL | #[rustc_symbol_name]
+   | ^^^^^^^^^^^^^^^^^^^^
+
+error: demangling(<c[464da6a86cb672f]::TupleByteBool<{(1u8, false)}>>)
+  --> $DIR/const-generics-structural-demangling.rs:40:1
+   |
+LL | #[rustc_symbol_name]
+   | ^^^^^^^^^^^^^^^^^^^^
+
+error: demangling-alt(<c::TupleByteBool<{(1, false)}>>)
+  --> $DIR/const-generics-structural-demangling.rs:40:1
+   |
+LL | #[rustc_symbol_name]
+   | ^^^^^^^^^^^^^^^^^^^^
+
+error: symbol-name(_RMs2_Csno73SFvQKx_1cINtB3_11OptionUsizeKVNtINtNtCs$HASH_4core6option6OptionjE4NoneUE)
+  --> $DIR/const-generics-structural-demangling.rs:50:1
+   |
+LL | #[rustc_symbol_name]
+   | ^^^^^^^^^^^^^^^^^^^^
+
+error: demangling(<c[464da6a86cb672f]::OptionUsize<{core[$HASH_HEX]::option::Option::<usize>::None}>>)
+  --> $DIR/const-generics-structural-demangling.rs:50:1
+   |
+LL | #[rustc_symbol_name]
+   | ^^^^^^^^^^^^^^^^^^^^
+
+error: demangling-alt(<c::OptionUsize<{core::option::Option::<usize>::None}>>)
+  --> $DIR/const-generics-structural-demangling.rs:50:1
+   |
+LL | #[rustc_symbol_name]
+   | ^^^^^^^^^^^^^^^^^^^^
+
+error: symbol-name(_RMs3_Csno73SFvQKx_1cINtB3_11OptionUsizeKVNtINtNtCs$HASH_4core6option6OptionjE4SomeTj0_EE)
+  --> $DIR/const-generics-structural-demangling.rs:58:1
+   |
+LL | #[rustc_symbol_name]
+   | ^^^^^^^^^^^^^^^^^^^^
+
+error: demangling(<c[464da6a86cb672f]::OptionUsize<{core[$HASH_HEX]::option::Option::<usize>::Some(0usize)}>>)
+  --> $DIR/const-generics-structural-demangling.rs:58:1
+   |
+LL | #[rustc_symbol_name]
+   | ^^^^^^^^^^^^^^^^^^^^
+
+error: demangling-alt(<c::OptionUsize<{core::option::Option::<usize>::Some(0)}>>)
+  --> $DIR/const-generics-structural-demangling.rs:58:1
+   |
+LL | #[rustc_symbol_name]
+   | ^^^^^^^^^^^^^^^^^^^^
+
+error: symbol-name(_RMs4_Csno73SFvQKx_1cINtB3_4Foo_KVNtB3_3FooS1sRe616263_2chc78_5sliceRAh1_h2_h3_EEE)
+  --> $DIR/const-generics-structural-demangling.rs:72:1
+   |
+LL | #[rustc_symbol_name]
+   | ^^^^^^^^^^^^^^^^^^^^
+
+error: demangling(<c[464da6a86cb672f]::Foo_<{c[464da6a86cb672f]::Foo { s: "abc", ch: 'x', slice: &[1u8, 2u8, 3u8] }}>>)
+  --> $DIR/const-generics-structural-demangling.rs:72:1
+   |
+LL | #[rustc_symbol_name]
+   | ^^^^^^^^^^^^^^^^^^^^
+
+error: demangling-alt(<c::Foo_<{c::Foo { s: "abc", ch: 'x', slice: &[1, 2, 3] }}>>)
+  --> $DIR/const-generics-structural-demangling.rs:72:1
+   |
+LL | #[rustc_symbol_name]
+   | ^^^^^^^^^^^^^^^^^^^^
+
+error: symbol-name(_RMs9_Csno73SFvQKx_1cINtB3_4Bar_KVNtB3_3BarS1xh7b_s_1xt1000_EE)
+  --> $DIR/const-generics-structural-demangling.rs:88:5
+   |
+LL |     #[rustc_symbol_name]
+   |     ^^^^^^^^^^^^^^^^^^^^
+...
+LL | duplicate_field_name_test!(x);
+   | ------------------------------ in this macro invocation
+   |
+   = note: this error originates in the macro `duplicate_field_name_test` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: demangling(<c[464da6a86cb672f]::Bar_<{c[464da6a86cb672f]::Bar { x: 123u8, x: 4096u16 }}>>)
+  --> $DIR/const-generics-structural-demangling.rs:88:5
+   |
+LL |     #[rustc_symbol_name]
+   |     ^^^^^^^^^^^^^^^^^^^^
+...
+LL | duplicate_field_name_test!(x);
+   | ------------------------------ in this macro invocation
+   |
+   = note: this error originates in the macro `duplicate_field_name_test` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: demangling-alt(<c::Bar_<{c::Bar { x: 123, x: 4096 }}>>)
+  --> $DIR/const-generics-structural-demangling.rs:88:5
+   |
+LL |     #[rustc_symbol_name]
+   |     ^^^^^^^^^^^^^^^^^^^^
+...
+LL | duplicate_field_name_test!(x);
+   | ------------------------------ in this macro invocation
+   |
+   = note: this error originates in the macro `duplicate_field_name_test` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 24 previous errors
+