1 files changed, 126 insertions, 0 deletions
diff --git a/third_party/rust/syn/tests/test_path.rs b/third_party/rust/syn/tests/test_path.rs
new file mode 100644
index 0000000000..c732eff70c
--- /dev/null
+++ b/third_party/rust/syn/tests/test_path.rs
@@ -0,0 +1,126 @@
+#[macro_use]
+mod macros;
+
+use proc_macro2::{Delimiter, Group, Ident, Punct, Spacing, Span, TokenStream, TokenTree};
+use quote::{quote, ToTokens};
+use std::iter::FromIterator;
+use syn::{parse_quote, Expr, Type, TypePath};
+
+#[test]
+fn parse_interpolated_leading_component() {
+    // mimics the token stream corresponding to `$mod::rest`
+    let tokens = TokenStream::from_iter(vec![
+        TokenTree::Group(Group::new(Delimiter::None, quote! { first })),
+        TokenTree::Punct(Punct::new(':', Spacing::Joint)),
+        TokenTree::Punct(Punct::new(':', Spacing::Alone)),
+        TokenTree::Ident(Ident::new("rest", Span::call_site())),
+    ]);
+
+    snapshot!(tokens.clone() as Expr, @r###"
+    Expr::Path {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "first",
+                    arguments: None,
+                },
+                PathSegment {
+                    ident: "rest",
+                    arguments: None,
+                },
+            ],
+        },
+    }
+    "###);
+
+    snapshot!(tokens as Type, @r###"
+    Type::Path {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "first",
+                    arguments: None,
+                },
+                PathSegment {
+                    ident: "rest",
+                    arguments: None,
+                },
+            ],
+        },
+    }
+    "###);
+}
+
+#[test]
+fn print_incomplete_qpath() {
+    // qpath with `as` token
+    let mut ty: TypePath = parse_quote!(<Self as A>::Q);
+    snapshot!(ty.to_token_stream(), @r###"
+    TokenStream(`< Self as A > :: Q`)
+    "###);
+    assert!(ty.path.segments.pop().is_some());
+    snapshot!(ty.to_token_stream(), @r###"
+    TokenStream(`< Self as A > ::`)
+    "###);
+    assert!(ty.path.segments.pop().is_some());
+    snapshot!(ty.to_token_stream(), @r###"
+    TokenStream(`< Self >`)
+    "###);
+    assert!(ty.path.segments.pop().is_none());
+
+    // qpath without `as` token
+    let mut ty: TypePath = parse_quote!(<Self>::A::B);
+    snapshot!(ty.to_token_stream(), @r###"
+    TokenStream(`< Self > :: A :: B`)
+    "###);
+    assert!(ty.path.segments.pop().is_some());
+    snapshot!(ty.to_token_stream(), @r###"
+    TokenStream(`< Self > :: A ::`)
+    "###);
+    assert!(ty.path.segments.pop().is_some());
+    snapshot!(ty.to_token_stream(), @r###"
+    TokenStream(`< Self > ::`)
+    "###);
+    assert!(ty.path.segments.pop().is_none());
+
+    // normal path
+    let mut ty: TypePath = parse_quote!(Self::A::B);
+    snapshot!(ty.to_token_stream(), @r###"
+    TokenStream(`Self :: A :: B`)
+    "###);
+    assert!(ty.path.segments.pop().is_some());
+    snapshot!(ty.to_token_stream(), @r###"
+    TokenStream(`Self :: A ::`)
+    "###);
+    assert!(ty.path.segments.pop().is_some());
+    snapshot!(ty.to_token_stream(), @r###"
+    TokenStream(`Self ::`)
+    "###);
+    assert!(ty.path.segments.pop().is_some());
+    snapshot!(ty.to_token_stream(), @r###"
+    TokenStream(``)
+    "###);
+    assert!(ty.path.segments.pop().is_none());
+}
+
+#[test]
+fn parse_parenthesized_path_arguments_with_disambiguator() {
+    #[rustfmt::skip]
+    let tokens = quote!(FnOnce::() -> !);
+    snapshot!(tokens as Type, @r###"
+    Type::Path {
+        path: Path {
+            segments: [
+                PathSegment {
+                    ident: "FnOnce",
+                    arguments: PathArguments::Parenthesized {
+                        output: Type(
+                            Type::Never,
+                        ),
+                    },
+                },
+            ],
+        },
+    }
+    "###);
+}