do not use std::panic::catch_unwind

Summary:
Recovering from ad-hoc panics is an anti-pattern that can lead to
undefined behavior. We need to be careful removing catch_unwinds()
from production code since it could be papering over real bugs,
but it should be safe to start with `hh_compile`.

While I'm here, remove some dead code.

Reviewed By: aorenste

Differential Revision: D34999905

fbshipit-source-id: 28b7e617db201e25db9af65103855dce91bda5d9

hphp/hack/src/hh_compile/compile.rs

@@ -221,7 +221,7 @@ fn process_single_file_impl(
     Ok((output, profile))
 }
 
-fn process_single_file_with_retry(
+pub(crate) fn process_single_file(
     opts: &SingleFileOpts,
     filepath: PathBuf,
     content: Vec<u8>,
@@ -234,20 +234,6 @@ fn process_single_file_with_retry(
     })?
 }
 
-pub(crate) fn process_single_file(
-    opts: &SingleFileOpts,
-    filepath: PathBuf,
-    content: Vec<u8>,
-) -> Result<(Vec<u8>, Profile)> {
-    match std::panic::catch_unwind(|| process_single_file_with_retry(opts, filepath, content)) {
-        Ok(r) => r,
-        Err(panic) => match panic.downcast::<String>() {
-            Ok(msg) => Err(anyhow!("panic: {}", msg)),
-            Err(_) => Err(anyhow!("panic: unknown")),
-        },
-    }
-}
-
 fn assert_regular_file(filepath: impl AsRef<Path>) {
     let filepath = filepath.as_ref();
     if !filepath.is_file() {
@@ -276,20 +262,6 @@ impl Config {
         ret
     }
 
-    #[allow(dead_code)] // will be used if --daemon (by HHVM)
-    fn with_merged<T>(
-        &mut self,
-        json: String,
-        cli_args: &[String],
-        f: impl FnOnce(&Options) -> T,
-    ) -> T {
-        self.jsons.push(json);
-        let hhbc_options = self.to_options(cli_args);
-        let ret = f(&hhbc_options);
-        self.jsons.pop();
-        ret
-    }
-
     fn to_options(&self, cli_args: &[String]) -> Options {
         Options::from_configs(&self.jsons, cli_args).unwrap()
     }