[ty] Minor cleanup for site-packages discovery logic (astral-sh#18446)

Author: AlexWaygood

crates/ty/src/args.rs

@@ -175,7 +175,9 @@ impl CheckCommand {
                 python_platform: self
                     .python_platform
                     .map(|platform| RangedValue::cli(platform.into())),
-                python: self.python.map(RelativePathBuf::cli),
+                python: self
+                    .python
+                    .map(|python| RangedValue::cli(RelativePathBuf::cli(python))),
                 typeshed: self.typeshed.map(RelativePathBuf::cli),
                 extra_paths: self.extra_search_path.map(|extra_search_paths| {
                     extra_search_paths

crates/ty/tests/cli.rs

@@ -1062,7 +1062,7 @@ fn config_file_broken_python_setting() -> anyhow::Result<()> {
     WARN ty is pre-release software and not ready for production use. Expect to encounter bugs, missing features, and fatal errors.
     ty failed
       Cause: Invalid search path settings
-      Cause: Failed to discover the site-packages directory: Invalid `--python` argument: `<temp_dir>/not-a-directory-or-executable` does not point to a Python executable or a directory on disk
+      Cause: Failed to discover the site-packages directory: Invalid `environment.python` setting in your configuration file: `<temp_dir>/not-a-directory-or-executable` does not point to a Python executable or a directory on disk
     ");
 
     Ok(())

crates/ty_project/src/metadata/options.rs

@@ -184,7 +184,11 @@ impl Options {
                 .map(|python_path| {
                     PythonPath::sys_prefix(
                         python_path.absolute(project_root, system),
-                        SysPrefixPathOrigin::PythonCliFlag,
+                        if python_path.source().is_cli() {
+                            SysPrefixPathOrigin::PythonCliFlag
+                        } else {
+                            SysPrefixPathOrigin::ConfigFileSetting
+                        },
                     )
                 })
                 .or_else(|| {
@@ -193,8 +197,8 @@ impl Options {
                     })
                 })
                 .or_else(|| {
-                    std::env::var("CONDA_PREFIX").ok().map(|path| {
-                        PythonPath::sys_prefix(path, SysPrefixPathOrigin::CondaPrefixVar)
+                    std::env::var("CONDA_PREFIX").ok().map(|conda_prefix| {
+                        PythonPath::sys_prefix(conda_prefix, SysPrefixPathOrigin::CondaPrefixVar)
                     })
                 })
                 .unwrap_or_else(|| {
@@ -387,7 +391,7 @@ pub struct EnvironmentOptions {
             python = "./.venv"
         "#
     )]
-    pub python: Option<RelativePathBuf>,
+    pub python: Option<RangedValue<RelativePathBuf>>,
 }
 
 #[derive(

crates/ty_project/src/metadata/value.rs

@@ -32,6 +32,10 @@ impl ValueSource {
             ValueSource::Cli => None,
         }
     }
+
+    pub const fn is_cli(&self) -> bool {
+        matches!(self, ValueSource::Cli)
+    }
 }
 
 thread_local! {

crates/ty_python_semantic/src/site_packages.rs

@@ -857,6 +857,8 @@ impl fmt::Display for SysPrefixPath {
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub enum SysPrefixPathOrigin {
+    /// The `sys.prefix` path came from a configuration file setting: `pyproject.toml` or `ty.toml`
+    ConfigFileSetting,
     /// The `sys.prefix` path came from a `--python` CLI flag
     PythonCliFlag,
     /// The `sys.prefix` path came from the `VIRTUAL_ENV` environment variable
@@ -878,7 +880,10 @@ impl SysPrefixPathOrigin {
     pub(crate) const fn must_be_virtual_env(self) -> bool {
         match self {
             Self::LocalVenv | Self::VirtualEnvVar => true,
-            Self::PythonCliFlag | Self::DerivedFromPyvenvCfg | Self::CondaPrefixVar => false,
+            Self::ConfigFileSetting
+            | Self::PythonCliFlag
+            | Self::DerivedFromPyvenvCfg
+            | Self::CondaPrefixVar => false,
         }
     }
 
@@ -888,7 +893,7 @@ impl SysPrefixPathOrigin {
     /// the `sys.prefix` directory, e.g. the `--python` CLI flag.
     pub(crate) const fn must_point_directly_to_sys_prefix(self) -> bool {
         match self {
-            Self::PythonCliFlag => false,
+            Self::PythonCliFlag | Self::ConfigFileSetting => false,
             Self::VirtualEnvVar
             | Self::CondaPrefixVar
             | Self::DerivedFromPyvenvCfg
@@ -901,6 +906,9 @@ impl Display for SysPrefixPathOrigin {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
         match self {
             Self::PythonCliFlag => f.write_str("`--python` argument"),
+            Self::ConfigFileSetting => {
+                f.write_str("`environment.python` setting in your configuration file")
+            }
             Self::VirtualEnvVar => f.write_str("`VIRTUAL_ENV` environment variable"),
             Self::CondaPrefixVar => f.write_str("`CONDA_PREFIX` environment variable"),
             Self::DerivedFromPyvenvCfg => f.write_str("derived `sys.prefix` path"),
@@ -1460,8 +1468,9 @@ mod tests {
     }
 
     #[test]
-    fn reject_env_that_is_not_a_directory() {
+    fn reject_configured_env_that_is_not_a_directory_or_executable() {
         let system = TestSystem::default();
+
         system
             .memory_file_system()
             .write_file_all("/env", "")