Use `panic::set_hook` to print the ICE message

5 files changed, 68 insertions, 47 deletions

diff --git a/Cargo.lock b/Cargo.lock
index ae641d6ae32..179bf59388a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3204,6 +3204,7 @@ version = "0.0.0"
 dependencies = [
  "env_logger 0.5.13",
  "graphviz",
+ "lazy_static 1.3.0",
  "log",
  "rustc",
  "rustc_ast_borrowck",
diff --git a/src/librustc_driver/Cargo.toml b/src/librustc_driver/Cargo.toml
index b030517e28e..8bd61c25843 100644
--- a/src/librustc_driver/Cargo.toml
+++ b/src/librustc_driver/Cargo.toml
@@ -11,6 +11,7 @@ crate-type = ["dylib"]
 
 [dependencies]
 graphviz = { path = "../libgraphviz" }
+lazy_static = "1.0"
 log = "0.4"
 env_logger = { version = "0.5", default-features = false }
 rustc = { path = "../librustc" }
diff --git a/src/librustc_driver/lib.rs b/src/librustc_driver/lib.rs
index e3ea92dc8ab..5b7ac14ba35 100644
--- a/src/librustc_driver/lib.rs
+++ b/src/librustc_driver/lib.rs
@@ -21,6 +21,8 @@ pub extern crate getopts;
 extern crate libc;
 #[macro_use]
 extern crate log;
+#[macro_use]
+extern crate lazy_static;
 
 pub extern crate rustc_plugin_impl as plugin;
 
@@ -1143,61 +1145,77 @@ fn extra_compiler_flags() -> Option<(Vec<String>, bool)> {
     }
 }
 
-/// Runs a procedure which will detect panics in the compiler and print nicer
-/// error messages rather than just failing the test.
+/// Runs a closure and catches unwinds triggered by fatal errors.
 ///
-/// The diagnostic emitter yielded to the procedure should be used for reporting
-/// errors of the compiler.
-pub fn report_ices_to_stderr_if_any<F: FnOnce() -> R, R>(f: F) -> Result<R, ErrorReported> {
+/// The compiler currently panics with a special sentinel value to abort
+/// compilation on fatal errors. This function catches that sentinel and turns
+/// the panic into a `Result` instead.
+pub fn catch_fatal_errors<F: FnOnce() -> R, R>(f: F) -> Result<R, ErrorReported> {
     catch_unwind(panic::AssertUnwindSafe(f)).map_err(|value| {
         if value.is::<errors::FatalErrorMarker>() {
             ErrorReported
         } else {
-            // Thread panicked without emitting a fatal diagnostic
-            eprintln!("");
-
-            let emitter = Box::new(errors::emitter::EmitterWriter::stderr(
-                errors::ColorConfig::Auto,
-                None,
-                false,
-                false,
-                None,
-            ));
-            let handler = errors::Handler::with_emitter(true, None, emitter);
-
-            // a .span_bug or .bug call has already printed what
-            // it wants to print.
-            if !value.is::<errors::ExplicitBug>() {
-                handler.emit(&MultiSpan::new(),
-                             "unexpected panic",
-                             errors::Level::Bug);
-            }
+            panic::resume_unwind(value);
+        }
+    })
+}
 
-            let mut xs: Vec<Cow<'static, str>> = vec![
-                "the compiler unexpectedly panicked. this is a bug.".into(),
-                format!("we would appreciate a bug report: {}", BUG_REPORT_URL).into(),
-                format!("rustc {} running on {}",
-                        option_env!("CFG_VERSION").unwrap_or("unknown_version"),
-                        config::host_triple()).into(),
-            ];
+lazy_static! {
+    static ref DEFAULT_HOOK: Box<dyn Fn(&panic::PanicInfo<'_>) + Sync + Send + 'static> = {
+        let hook = panic::take_hook();
+        panic::set_hook(Box::new(report_ice));
+        hook
+    };
+}
 
-            if let Some((flags, excluded_cargo_defaults)) = extra_compiler_flags() {
-                xs.push(format!("compiler flags: {}", flags.join(" ")).into());
+pub fn report_ice(info: &panic::PanicInfo<'_>) {
+    (*DEFAULT_HOOK)(info);
+
+    // Thread panicked without emitting a fatal diagnostic
+    eprintln!();
+
+    let emitter = Box::new(errors::emitter::EmitterWriter::stderr(
+        errors::ColorConfig::Auto,
+        None,
+        false,
+        false,
+        None,
+    ));
+    let handler = errors::Handler::with_emitter(true, None, emitter);
+
+    // a .span_bug or .bug call has already printed what
+    // it wants to print.
+    if !info.payload().is::<errors::ExplicitBug>() {
+        handler.emit(&MultiSpan::new(),
+                     "unexpected panic",
+                     errors::Level::Bug);
+    }
 
-                if excluded_cargo_defaults {
-                    xs.push("some of the compiler flags provided by cargo are hidden".into());
-                }
-            }
+    let mut xs: Vec<Cow<'static, str>> = vec![
+        "the compiler unexpectedly panicked. this is a bug.".into(),
+        format!("we would appreciate a bug report: {}", BUG_REPORT_URL).into(),
+        format!("rustc {} running on {}",
+                option_env!("CFG_VERSION").unwrap_or("unknown_version"),
+                config::host_triple()).into(),
+    ];
 
-            for note in &xs {
-                handler.emit(&MultiSpan::new(),
-                             note,
-                             errors::Level::Note);
-            }
+    if let Some((flags, excluded_cargo_defaults)) = extra_compiler_flags() {
+        xs.push(format!("compiler flags: {}", flags.join(" ")).into());
 
-            panic::resume_unwind(Box::new(errors::FatalErrorMarker));
+        if excluded_cargo_defaults {
+            xs.push("some of the compiler flags provided by cargo are hidden".into());
         }
-    })
+    }
+
+    for note in &xs {
+        handler.emit(&MultiSpan::new(),
+                     note,
+                     errors::Level::Note);
+    }
+}
+
+pub fn install_ice_hook() {
+    lazy_static::initialize(&DEFAULT_HOOK);
 }
 
 /// This allows tools to enable rust logging without having to magically match rustc's
@@ -1210,7 +1228,8 @@ pub fn main() {
     let start = Instant::now();
     init_rustc_env_logger();
     let mut callbacks = TimePassesCallbacks::default();
-    let result = report_ices_to_stderr_if_any(|| {
+    install_ice_hook();
+    let result = catch_fatal_errors(|| {
         let args = env::args_os().enumerate()
             .map(|(i, arg)| arg.into_string().unwrap_or_else(|arg| {
                     early_error(ErrorOutputType::default(),
diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index 87dac0f2268..0b366da29d3 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -453,7 +453,7 @@ where R: 'static + Send,
     // First, parse the crate and extract all relevant information.
     info!("starting to run rustc");
 
-    let result = rustc_driver::report_ices_to_stderr_if_any(move || {
+    let result = rustc_driver::catch_fatal_errors(move || {
         let crate_name = options.crate_name.clone();
         let crate_version = options.crate_version.clone();
         let (mut krate, renderinfo, renderopts) = core::run_core(options);
diff --git a/src/test/ui-fulldeps/compiler-calls.rs b/src/test/ui-fulldeps/compiler-calls.rs
index ea24f5809d5..bd9113c7079 100644
--- a/src/test/ui-fulldeps/compiler-calls.rs
+++ b/src/test/ui-fulldeps/compiler-calls.rs
@@ -24,7 +24,7 @@ impl rustc_driver::Callbacks for TestCalls<'_> {
 fn main() {
     let mut count = 1;
     let args = vec!["compiler-calls".to_string(), "foo.rs".to_string()];
-    rustc_driver::report_ices_to_stderr_if_any(|| {
+    rustc_driver::catch_fatal_errors(|| {
         rustc_driver::run_compiler(&args, &mut TestCalls { count: &mut count }, None, None).ok();
     }).ok();
     assert_eq!(count, 2);