Correct Pyston tag format (#10580)

## Summary

Empirically, it looks like the format here is slightly different than
what we had in the code? Our integration test caught it.

crates/uv-platform-tags/src/abi_tag.rs

@@ -39,11 +39,8 @@ pub enum AbiTag {
         python_version: (u8, u8),
         implementation_version: (u8, u8),
     },
-    /// Ex) `pyston38-pyston_23`
-    Pyston {
-        python_version: (u8, u8),
-        implementation_version: (u8, u8),
-    },
+    /// Ex) `pyston_23_x86_64_linux_gnu`
+    Pyston { implementation_version: (u8, u8) },
 }
 
 impl std::fmt::Display for AbiTag {
@@ -82,13 +79,9 @@ impl std::fmt::Display for AbiTag {
                 )
             }
             Self::Pyston {
-                python_version: (py_major, py_minor),
                 implementation_version: (impl_major, impl_minor),
             } => {
-                write!(
-                    f,
-                    "pyston{py_major}{py_minor}-pyston_{impl_major}{impl_minor}"
-                )
+                write!(f, "pyston_{impl_major}{impl_minor}_x86_64_linux_gnu")
             }
         }
     }
@@ -229,24 +222,21 @@ impl FromStr for AbiTag {
                 implementation_version: (impl_major, impl_minor),
             })
         } else if let Some(rest) = s.strip_prefix("pyston") {
-            // Ex) `pyston38-pyston_23`
-            let version_end = rest
-                .find('-')
+            // Ex) `pyston_23_x86_64_linux_gnu`
+            let rest = rest
+                .strip_prefix("_")
                 .ok_or_else(|| ParseAbiTagError::InvalidFormat {
                     implementation: "Pyston",
                     tag: s.to_string(),
                 })?;
-            let version_str = &rest[..version_end];
-            let (major, minor) = parse_python_version(version_str, "Pyston", s)?;
-            let rest = rest[version_end + 1..]
-                .strip_prefix("pyston_")
-                .ok_or_else(|| ParseAbiTagError::InvalidFormat {
+            let rest = rest.strip_suffix("_x86_64_linux_gnu").ok_or_else(|| {
+                ParseAbiTagError::InvalidFormat {
                     implementation: "Pyston",
                     tag: s.to_string(),
-                })?;
+                }
+            })?;
             let (impl_major, impl_minor) = parse_impl_version(rest, "Pyston", s)?;
             Ok(Self::Pyston {
-                python_version: (major, minor),
                 implementation_version: (impl_major, impl_minor),
             })
         } else {
@@ -426,31 +416,23 @@ mod tests {
     #[test]
     fn pyston_abi() {
         let tag = AbiTag::Pyston {
-            python_version: (3, 8),
             implementation_version: (2, 3),
         };
-        assert_eq!(AbiTag::from_str("pyston38-pyston_23"), Ok(tag));
-        assert_eq!(tag.to_string(), "pyston38-pyston_23");
+        assert_eq!(AbiTag::from_str("pyston_23_x86_64_linux_gnu"), Ok(tag));
+        assert_eq!(tag.to_string(), "pyston_23_x86_64_linux_gnu");
 
         assert_eq!(
-            AbiTag::from_str("pyston38"),
+            AbiTag::from_str("pyston23_x86_64_linux_gnu"),
             Err(ParseAbiTagError::InvalidFormat {
                 implementation: "Pyston",
-                tag: "pyston38".to_string()
+                tag: "pyston23_x86_64_linux_gnu".to_string()
             })
         );
         assert_eq!(
-            AbiTag::from_str("pyston38_23"),
-            Err(ParseAbiTagError::InvalidFormat {
-                implementation: "Pyston",
-                tag: "pyston38_23".to_string()
-            })
-        );
-        assert_eq!(
-            AbiTag::from_str("pyston38-pyston_XY"),
+            AbiTag::from_str("pyston_XY_x86_64_linux_gnu"),
             Err(ParseAbiTagError::InvalidImplMajorVersion {
                 implementation: "Pyston",
-                tag: "pyston38-pyston_XY".to_string()
+                tag: "pyston_XY_x86_64_linux_gnu".to_string()
             })
         );
     }

crates/uv-platform-tags/src/language_tag.rs

@@ -30,7 +30,7 @@ pub enum LanguageTag {
     PyPy { python_version: (u8, u8) },
     /// Ex) `graalpy310`
     GraalPy { python_version: (u8, u8) },
-    /// Ex) `pt38`
+    /// Ex) `pyston38`
     Pyston { python_version: (u8, u8) },
 }
 
@@ -64,7 +64,7 @@ impl std::fmt::Display for LanguageTag {
             Self::Pyston {
                 python_version: (major, minor),
             } => {
-                write!(f, "pt{major}{minor}")
+                write!(f, "pyston{major}{minor}")
             }
         }
     }
@@ -111,28 +111,48 @@ impl FromStr for LanguageTag {
         if s == "none" {
             Ok(Self::None)
         } else if let Some(py) = s.strip_prefix("py") {
-            if py.len() == 1 {
-                // Ex) `py3`
-                let major = py
-                    .chars()
-                    .next()
-                    .ok_or_else(|| ParseLanguageTagError::MissingMajorVersion {
+            match py.len() {
+                0 => {
+                    return Err(ParseLanguageTagError::MissingMajorVersion {
                         implementation: "Python",
                         tag: s.to_string(),
-                    })?
-                    .to_digit(10)
-                    .ok_or_else(|| ParseLanguageTagError::InvalidMajorVersion {
-                        implementation: "Python",
-                        tag: s.to_string(),
-                    })? as u8;
-                Ok(Self::Python { major, minor: None })
-            } else {
-                // Ex) `py39`
-                let (major, minor) = parse_python_version(py, "Python", s)?;
-                Ok(Self::Python {
-                    major,
-                    minor: Some(minor),
-                })
+                    });
+                }
+                1 => {
+                    // Ex) `py3`
+                    let major = py
+                        .chars()
+                        .next()
+                        .ok_or_else(|| ParseLanguageTagError::MissingMajorVersion {
+                            implementation: "Python",
+                            tag: s.to_string(),
+                        })?
+                        .to_digit(10)
+                        .ok_or_else(|| ParseLanguageTagError::InvalidMajorVersion {
+                            implementation: "Python",
+                            tag: s.to_string(),
+                        })? as u8;
+                    Ok(Self::Python { major, minor: None })
+                }
+                2 | 3 => {
+                    // Ex) `py39`, `py310`
+                    let (major, minor) = parse_python_version(py, "Python", s)?;
+                    Ok(Self::Python {
+                        major,
+                        minor: Some(minor),
+                    })
+                }
+                _ => {
+                    if let Some(pyston) = py.strip_prefix("ston") {
+                        // Ex) `pyston38`
+                        let (major, minor) = parse_python_version(pyston, "Pyston", s)?;
+                        Ok(Self::Pyston {
+                            python_version: (major, minor),
+                        })
+                    } else {
+                        Err(ParseLanguageTagError::UnknownFormat(s.to_string()))
+                    }
+                }
             }
         } else if let Some(cp) = s.strip_prefix("cp") {
             // Ex) `cp39`
@@ -152,12 +172,6 @@ impl FromStr for LanguageTag {
             Ok(Self::GraalPy {
                 python_version: (major, minor),
             })
-        } else if let Some(pt) = s.strip_prefix("pt") {
-            // Ex) `pt38`
-            let (major, minor) = parse_python_version(pt, "Pyston", s)?;
-            Ok(Self::Pyston {
-                python_version: (major, minor),
-            })
         } else {
             Err(ParseLanguageTagError::UnknownFormat(s.to_string()))
         }
@@ -340,28 +354,28 @@ mod tests {
         let tag = LanguageTag::Pyston {
             python_version: (3, 8),
         };
-        assert_eq!(LanguageTag::from_str("pt38"), Ok(tag));
-        assert_eq!(tag.to_string(), "pt38");
+        assert_eq!(LanguageTag::from_str("pyston38"), Ok(tag));
+        assert_eq!(tag.to_string(), "pyston38");
 
         assert_eq!(
-            LanguageTag::from_str("pt"),
+            LanguageTag::from_str("pyston"),
             Err(ParseLanguageTagError::MissingMajorVersion {
                 implementation: "Pyston",
-                tag: "pt".to_string()
+                tag: "pyston".to_string()
             })
         );
         assert_eq!(
-            LanguageTag::from_str("ptX"),
+            LanguageTag::from_str("pystonX"),
             Err(ParseLanguageTagError::InvalidMajorVersion {
                 implementation: "Pyston",
-                tag: "ptX".to_string()
+                tag: "pystonX".to_string()
             })
         );
         assert_eq!(
-            LanguageTag::from_str("pt3X"),
+            LanguageTag::from_str("pyston3X"),
             Err(ParseLanguageTagError::InvalidMinorVersion {
                 implementation: "Pyston",
-                tag: "pt3X".to_string()
+                tag: "pyston3X".to_string()
             })
         );
     }

crates/uv-platform-tags/src/tags.rs

@@ -376,7 +376,7 @@ impl Implementation {
             Self::PyPy => LanguageTag::PyPy { python_version },
             // Ex) `graalpy310`
             Self::GraalPy => LanguageTag::GraalPy { python_version },
-            // Ex) `pt38``
+            // Ex) `pyston38`
             Self::Pyston => LanguageTag::Pyston { python_version },
         }
     }
@@ -398,9 +398,8 @@ impl Implementation {
                 python_version,
                 implementation_version,
             },
-            // Ex) `pyston38-pyston_23`
+            // Ex) `pyston_23_x86_64_linux`
             Self::Pyston => AbiTag::Pyston {
-                python_version,
                 implementation_version,
             },
         }

crates/uv-resolver/src/requires_python.rs

@@ -469,9 +469,6 @@ impl RequiresPython {
                 } | AbiTag::GraalPy {
                     python_version: (2, ..),
                     ..
-                } | AbiTag::Pyston {
-                    python_version: (2, ..),
-                    ..
                 }
             ) {
                 // Python 2 is never allowed.
@@ -487,10 +484,6 @@ impl RequiresPython {
             | AbiTag::GraalPy {
                 python_version: (3, minor),
                 ..
-            }
-            | AbiTag::Pyston {
-                python_version: (3, minor),
-                ..
             } = abi_tag
             {
                 // Ex) If the wheel bound is `3.6`, then it doesn't match `>=3.10`.