feat(php-shim): give ported exceptions PHP's class hierarchy

Ported exceptions were flat structs reached with `downcast_ref`, so
Composer's `catch (\RuntimeException $e)` only matched the exact leaf
type and `get_class($e)` had nothing to report. Each exception now
embeds an instance of the class it extends and travels inside an
`AnyThrowable`; `Catch::catch`/`catch_mut` walk that chain, and
`PhpClass::php_class_name` yields the PHP FQCN.

Dropping the `std::error::Error` impls from the exception types leaves
`AnyThrowable` as the only route into an `anyhow::Error`, so the walk
cannot be bypassed. A `no_exception_downcast` linter catches the
`downcast::<X>()` calls that would now silently answer `None`.

Three sites change behavior as a result: the `TransportException`
exit-code override reaches `MaxFileSizeExceededException`, the
`catch (\LogicException)` in findSimilar() reaches its subclasses, and
rendered exception titles carry the real class name rather than a
guess. `get_class_err()` is no longer a `todo!()`, which re-enables
FilesystemRepositoryTest::testCorruptedRepositoryFile.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

3 files changed, 39 insertions, 49 deletions

diff --git a/crates/shirabe-class-map-generator/src/class_map.rs b/crates/shirabe-class-map-generator/src/class_map.rs
index 0b828be4..65eb3790 100644
--- a/crates/shirabe-class-map-generator/src/class_map.rs
+++ b/crates/shirabe-class-map-generator/src/class_map.rs
@@ -92,10 +92,11 @@ impl ClassMap {
     pub fn get_class_path(&self, class_name: &str) -> anyhow::Result<&str> {
         match self.map.get(class_name) {
             Some(path) => Ok(path.as_str()),
-            None => Err(anyhow::anyhow!(OutOfBoundsException {
-                message: format!("Class {} is not present in the map", class_name),
-                code: 0,
-            })),
+            None => Err(OutOfBoundsException::new(format!(
+                "Class {} is not present in the map",
+                class_name
+            ))
+            .into()),
         }
     }
 
diff --git a/crates/shirabe-class-map-generator/src/class_map_generator.rs b/crates/shirabe-class-map-generator/src/class_map_generator.rs
index 0f98ca27..d1a11c99 100644
--- a/crates/shirabe-class-map-generator/src/class_map_generator.rs
+++ b/crates/shirabe-class-map-generator/src/class_map_generator.rs
@@ -74,19 +74,15 @@ impl ClassMapGenerator {
         excluded_dirs: Vec<String>,
     ) -> anyhow::Result<()> {
         if !matches!(autoload_type, "psr-0" | "psr-4" | "classmap") {
-            return Err(anyhow::anyhow!(InvalidArgumentException {
-                message: "$autoloadType must be one of: \"psr-0\", \"psr-4\" or \"classmap\""
-                    .to_string(),
-                code: 0,
-            }));
+            return Err(InvalidArgumentException::new(
+                "$autoloadType must be one of: \"psr-0\", \"psr-4\" or \"classmap\"".to_string(),
+            )
+            .into());
         }
 
         let base_path: Option<String> = if autoload_type != "classmap" {
             if namespace.is_none() {
-                return Err(anyhow::anyhow!(InvalidArgumentException {
-                    message: "$namespace must be given (even if it is an empty string if you do not want to filter) when specifying a psr-0 or psr-4 autoload type".to_string(),
-                    code: 0,
-                }));
+                return Err(InvalidArgumentException::new("$namespace must be given (even if it is an empty string if you do not want to filter) when specifying a psr-0 or psr-4 autoload type".to_string()).into());
             }
             Some(path.to_owned())
         } else {
@@ -116,13 +112,10 @@ impl ClassMapGenerator {
                 .iter()
                 .collect()
         } else {
-            return Err(anyhow::anyhow!(RuntimeException {
-                message: format!(
-                    "Could not scan for classes inside \"{}\" which does not appear to be a file nor a folder",
-                    path
-                ),
-                code: 0,
-            }));
+            return Err(RuntimeException::new(format!(
+                "Could not scan for classes inside \"{}\" which does not appear to be a file nor a folder",
+                path
+            )).into());
         };
 
         let cwd = realpath(getcwd().unwrap_or_default()).unwrap_or_default();
@@ -131,10 +124,11 @@ impl ClassMapGenerator {
             let mut file_path = match file.to_str() {
                 Some(s) => s.to_string(),
                 None => {
-                    return Err(anyhow::anyhow!(RuntimeException {
-                        message: format!("Path contains invalid UTF-8: {}", file.display()),
-                        code: 0,
-                    }));
+                    return Err(RuntimeException::new(format!(
+                        "Path contains invalid UTF-8: {}",
+                        file.display()
+                    ))
+                    .into());
                 }
             };
             let ext = pathinfo(&file_path, PATHINFO_EXTENSION);
@@ -158,10 +152,11 @@ impl ClassMapGenerator {
             }
 
             if file_path.is_empty() {
-                return Err(anyhow::anyhow!(LogicException {
-                    message: format!("Got an empty $filePath for {}", file.display()),
-                    code: 0,
-                }));
+                return Err(LogicException::new(format!(
+                    "Got an empty $filePath for {}",
+                    file.display()
+                ))
+                .into());
             }
 
             let real_path = if is_stream_wrapper_path {
@@ -170,13 +165,11 @@ impl ClassMapGenerator {
                 match realpath(&file_path) {
                     Some(p) => p,
                     None => {
-                        return Err(anyhow::anyhow!(RuntimeException {
-                            message: format!(
-                                "realpath of {} failed to resolve, got false",
-                                file_path
-                            ),
-                            code: 0,
-                        }));
+                        return Err(RuntimeException::new(format!(
+                            "realpath of {} failed to resolve, got false",
+                            file_path
+                        ))
+                        .into());
                     }
                 }
             };
@@ -284,10 +277,10 @@ impl ClassMapGenerator {
                 };
                 sub_path = str_replace("\\", DIRECTORY_SEPARATOR, &sub_namespace);
             } else {
-                return Err(anyhow::anyhow!(InvalidArgumentException {
-                    message: "$namespaceType must be \"psr-0\" or \"psr-4\"".to_string(),
-                    code: 0,
-                }));
+                return Err(InvalidArgumentException::new(
+                    "$namespaceType must be \"psr-0\" or \"psr-4\"".to_string(),
+                )
+                .into());
             }
 
             if sub_path == real_sub_path {
@@ -403,10 +396,10 @@ impl ClassMapGenerator {
     fn get_cwd() -> anyhow::Result<String> {
         match getcwd() {
             Some(cwd) => Ok(cwd),
-            None => Err(anyhow::anyhow!(RuntimeException {
-                message: "Could not determine the current working directory".to_string(),
-                code: 0,
-            })),
+            None => Err(RuntimeException::new(
+                "Could not determine the current working directory".to_string(),
+            )
+            .into()),
         }
     }
 }
diff --git a/crates/shirabe-class-map-generator/src/php_file_parser.rs b/crates/shirabe-class-map-generator/src/php_file_parser.rs
index cf30c240..88676407 100644
--- a/crates/shirabe-class-map-generator/src/php_file_parser.rs
+++ b/crates/shirabe-class-map-generator/src/php_file_parser.rs
@@ -1,7 +1,6 @@
 //! ref: composer/vendor/composer/class-map-generator/src/PhpFileParser.php
 
 use crate::php_file_cleaner::PhpFileCleaner;
-use anyhow::anyhow;
 use indexmap::IndexMap;
 use shirabe_external_packages::composer::pcre::{CaptureKey, Preg};
 use shirabe_php_shim::{
@@ -18,10 +17,7 @@ impl PhpFileParser {
         let extra_types = Self::get_extra_types();
 
         if !function_exists("php_strip_whitespace") {
-            return Err(anyhow!(RuntimeException {
-                message: "Classmap generation relies on the php_strip_whitespace function, but it has been disabled by the disable_functions directive.".to_string(),
-                code: 0,
-            }));
+            return Err(RuntimeException::new("Classmap generation relies on the php_strip_whitespace function, but it has been disabled by the disable_functions directive.".to_string()).into());
         }
 
         // Use @ here instead of Silencer to actively suppress 'unhelpful' output
@@ -63,7 +59,7 @@ impl PhpFileParser {
                 );
             }
 
-            return Err(anyhow!(RuntimeException { message, code: 0 }));
+            return Err(RuntimeException::new(message).into());
         }
 
         // return early if there is no chance of matching anything in this file