Auto merge of #60584 - jonas-schievink:ice-panic-hook, r=oli-obk

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

This allows custom frontends and backends to override the hook with their own, for example to point people to a different issue tracker.

ICE messages are printed in a slightly different order now. Nightly prints:

```
thread 'rustc' panicked at 'called `Option::unwrap()` on a `None` value', src/libcore/option.rs:347:21
note: Run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
error: aborting due to 2 previous errors

Some errors have detailed explanations: E0277, E0658.
For more information about an error, try `rustc --explain E0277`.

error: internal compiler error: unexpected panic

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.36.0-nightly (08bfe1612 2019-05-02) running on x86_64-unknown-linux-gnu
```

After this PR, rustc prints:

```
thread 'rustc' panicked at 'called `Option::unwrap()` on a `None` value', src/libcore/option.rs:347:21
note: Run with `RUST_BACKTRACE=1` environment variable to display a backtrace.

error: internal compiler error: unexpected panic

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.36.0-dev running on x86_64-unknown-linux-gnu

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0277, E0658.
For more information about an error, try `rustc --explain E0277`.
```

14 files changed, 116 insertions, 94 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 57e4a227427..679a02441c4 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3014,7 +3014,6 @@ dependencies = [
  "fmt_macros",
  "graphviz",
  "jobserver",
- "lazy_static 1.3.0",
  "log",
  "measureme",
  "num_cpus",
@@ -3370,6 +3369,7 @@ version = "0.0.0"
 dependencies = [
  "env_logger",
  "graphviz",
+ "lazy_static 1.3.0",
  "log",
  "rustc",
  "rustc_ast_borrowck",
diff --git a/src/librustc/Cargo.toml b/src/librustc/Cargo.toml
index a479fabafc0..66071d6b6ce 100644
--- a/src/librustc/Cargo.toml
+++ b/src/librustc/Cargo.toml
@@ -15,7 +15,6 @@ bitflags = "1.0"
 fmt_macros = { path = "../libfmt_macros" }
 graphviz = { path = "../libgraphviz" }
 jobserver = "0.1"
-lazy_static = "1.0.0"
 num_cpus = "1.0"
 scoped-tls = "1.0"
 log = { version = "0.4", features = ["release_max_level_info", "std"] }
diff --git a/src/librustc/lib.rs b/src/librustc/lib.rs
index 63ef82a7401..7a01ae6b6d9 100644
--- a/src/librustc/lib.rs
+++ b/src/librustc/lib.rs
@@ -67,7 +67,6 @@
 
 #[macro_use] extern crate bitflags;
 extern crate getopts;
-#[macro_use] extern crate lazy_static;
 #[macro_use] extern crate scoped_tls;
 #[cfg(windows)]
 extern crate libc;
diff --git a/src/librustc/util/common.rs b/src/librustc/util/common.rs
index 7118d05204c..2475b93d95f 100644
--- a/src/librustc/util/common.rs
+++ b/src/librustc/util/common.rs
@@ -5,17 +5,13 @@ use rustc_data_structures::{fx::FxHashMap, sync::Lock};
 use std::cell::{RefCell, Cell};
 use std::fmt::Debug;
 use std::hash::Hash;
-use std::panic;
-use std::env;
 use std::time::{Duration, Instant};
 
 use std::sync::mpsc::{Sender};
 use syntax_pos::{SpanData};
 use syntax::symbol::{Symbol, sym};
 use rustc_macros::HashStable;
-use crate::ty::TyCtxt;
 use crate::dep_graph::{DepNode};
-use lazy_static;
 use crate::session::Session;
 
 #[cfg(test)]
@@ -31,39 +27,6 @@ pub struct ErrorReported;
 
 thread_local!(static TIME_DEPTH: Cell<usize> = Cell::new(0));
 
-lazy_static! {
-    static ref DEFAULT_HOOK: Box<dyn Fn(&panic::PanicInfo<'_>) + Sync + Send + 'static> = {
-        let hook = panic::take_hook();
-        panic::set_hook(Box::new(panic_hook));
-        hook
-    };
-}
-
-fn panic_hook(info: &panic::PanicInfo<'_>) {
-    (*DEFAULT_HOOK)(info);
-
-    let backtrace = env::var_os("RUST_BACKTRACE").map(|x| &x != "0").unwrap_or(false);
-
-    if backtrace {
-        TyCtxt::try_print_query_stack();
-    }
-
-    #[cfg(windows)]
-    unsafe {
-        if env::var("RUSTC_BREAK_ON_ICE").is_ok() {
-            extern "system" {
-                fn DebugBreak();
-            }
-            // Trigger a debugger if we crashed during bootstrap.
-            DebugBreak();
-        }
-    }
-}
-
-pub fn install_panic_hook() {
-    lazy_static::initialize(&DEFAULT_HOOK);
-}
-
 /// Parameters to the `Dump` variant of type `ProfileQueriesMsg`.
 #[derive(Clone,Debug)]
 pub struct ProfQDumpParams {
diff --git a/src/librustc_driver/Cargo.toml b/src/librustc_driver/Cargo.toml
index a839ee56b2b..25f67b30468 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 = "0.6", default-features = false }
 rustc = { path = "../librustc" }
diff --git a/src/librustc_driver/lib.rs b/src/librustc_driver/lib.rs
index a912ea3c358..005cdcfaf68 100644
--- a/src/librustc_driver/lib.rs
+++ b/src/librustc_driver/lib.rs
@@ -20,6 +20,8 @@ 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;
 
@@ -35,8 +37,8 @@ use rustc::session::{early_error, early_warn};
 use rustc::lint::Lint;
 use rustc::lint;
 use rustc::hir::def_id::LOCAL_CRATE;
-use rustc::util::common::{ErrorReported, install_panic_hook, print_time_passes_entry};
-use rustc::util::common::{set_time_depth, time};
+use rustc::ty::TyCtxt;
+use rustc::util::common::{set_time_depth, time, print_time_passes_entry, ErrorReported};
 use rustc_metadata::locator;
 use rustc_metadata::cstore::CStore;
 use rustc_codegen_utils::codegen_backend::CodegenBackend;
@@ -161,8 +163,6 @@ pub fn run_compiler(
         None => return Ok(()),
     };
 
-    install_panic_hook();
-
     let (sopts, cfg) = config::build_session_options_and_crate_config(&matches);
 
     let mut dummy_config = |sopts, cfg, diagnostic_output| {
@@ -1151,61 +1151,105 @@ 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 unwinds 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(|info| report_ice(info, BUG_REPORT_URL)));
+        hook
+    };
+}
 
-            if let Some((flags, excluded_cargo_defaults)) = extra_compiler_flags() {
-                xs.push(format!("compiler flags: {}", flags.join(" ")).into());
+/// Prints the ICE message, including backtrace and query stack.
+///
+/// The message will point the user at `bug_report_url` to report the ICE.
+///
+/// When `install_ice_hook` is called, this function will be called as the panic
+/// hook.
+pub fn report_ice(info: &panic::PanicInfo<'_>, bug_report_url: &str) {
+    // Invoke the default handler, which prints the actual panic message and optionally a backtrace
+    (*DEFAULT_HOOK)(info);
+
+    // Separate the output with an empty line
+    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);
+    }
+
+    // If backtraces are enabled, also print the query stack
+    let backtrace = env::var_os("RUST_BACKTRACE").map(|x| &x != "0").unwrap_or(false);
+
+    if backtrace {
+        TyCtxt::try_print_query_stack();
+    }
+
+    #[cfg(windows)]
+    unsafe {
+        if env::var("RUSTC_BREAK_ON_ICE").is_ok() {
+            extern "system" {
+                fn DebugBreak();
+            }
+            // Trigger a debugger if we crashed during bootstrap
+            DebugBreak();
+        }
+    }
+}
+
+/// Installs a panic hook that will print the ICE message on unexpected panics.
+///
+/// A custom rustc driver can skip calling this to set up a custom ICE hook.
+pub fn install_ice_hook() {
+    lazy_static::initialize(&DEFAULT_HOOK);
 }
 
 /// This allows tools to enable rust logging without having to magically match rustc's
@@ -1218,7 +1262,8 @@ 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 d77e790d4a4..0b9e717221f 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -473,7 +473,7 @@ 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);
diff --git a/src/test/ui/proc-macro/invalid-punct-ident-1.rs b/src/test/ui/proc-macro/invalid-punct-ident-1.rs
index c9881ad2c38..94a4b403d5a 100644
--- a/src/test/ui/proc-macro/invalid-punct-ident-1.rs
+++ b/src/test/ui/proc-macro/invalid-punct-ident-1.rs
@@ -3,6 +3,11 @@
 // FIXME https://github.com/rust-lang/rust/issues/59998
 // normalize-stderr-test "thread.*panicked.*proc_macro_server.rs.*\n" -> ""
 // normalize-stderr-test "note:.*RUST_BACKTRACE=1.*\n" -> ""
+// normalize-stderr-test "\nerror: internal compiler error.*\n\n" -> ""
+// normalize-stderr-test "note:.*unexpectedly panicked.*\n\n" -> ""
+// normalize-stderr-test "note: we would appreciate a bug report.*\n\n" -> ""
+// normalize-stderr-test "note: compiler flags.*\n\n" -> ""
+// normalize-stderr-test "note: rustc.*running on.*\n\n" -> ""
 
 #[macro_use]
 extern crate invalid_punct_ident;
diff --git a/src/test/ui/proc-macro/invalid-punct-ident-1.stderr b/src/test/ui/proc-macro/invalid-punct-ident-1.stderr
index 40333a3f4c2..107f5fb515b 100644
--- a/src/test/ui/proc-macro/invalid-punct-ident-1.stderr
+++ b/src/test/ui/proc-macro/invalid-punct-ident-1.stderr
@@ -1,5 +1,5 @@
 error: proc macro panicked
-  --> $DIR/invalid-punct-ident-1.rs:10:1
+  --> $DIR/invalid-punct-ident-1.rs:15:1
    |
 LL | invalid_punct!();
    | ^^^^^^^^^^^^^^^^^
diff --git a/src/test/ui/proc-macro/invalid-punct-ident-2.rs b/src/test/ui/proc-macro/invalid-punct-ident-2.rs
index 15e2286a650..778b7eeecd7 100644
--- a/src/test/ui/proc-macro/invalid-punct-ident-2.rs
+++ b/src/test/ui/proc-macro/invalid-punct-ident-2.rs
@@ -3,6 +3,11 @@
 // FIXME https://github.com/rust-lang/rust/issues/59998
 // normalize-stderr-test "thread.*panicked.*proc_macro_server.rs.*\n" -> ""
 // normalize-stderr-test "note:.*RUST_BACKTRACE=1.*\n" -> ""
+// normalize-stderr-test "\nerror: internal compiler error.*\n\n" -> ""
+// normalize-stderr-test "note:.*unexpectedly panicked.*\n\n" -> ""
+// normalize-stderr-test "note: we would appreciate a bug report.*\n\n" -> ""
+// normalize-stderr-test "note: compiler flags.*\n\n" -> ""
+// normalize-stderr-test "note: rustc.*running on.*\n\n" -> ""
 
 #[macro_use]
 extern crate invalid_punct_ident;
diff --git a/src/test/ui/proc-macro/invalid-punct-ident-2.stderr b/src/test/ui/proc-macro/invalid-punct-ident-2.stderr
index ec97e265c3f..f1b9ecc6cbf 100644
--- a/src/test/ui/proc-macro/invalid-punct-ident-2.stderr
+++ b/src/test/ui/proc-macro/invalid-punct-ident-2.stderr
@@ -1,5 +1,5 @@
 error: proc macro panicked
-  --> $DIR/invalid-punct-ident-2.rs:10:1
+  --> $DIR/invalid-punct-ident-2.rs:15:1
    |
 LL | invalid_ident!();
    | ^^^^^^^^^^^^^^^^^
diff --git a/src/test/ui/proc-macro/invalid-punct-ident-3.rs b/src/test/ui/proc-macro/invalid-punct-ident-3.rs
index 629bbaa9e38..f68ee3de7f4 100644
--- a/src/test/ui/proc-macro/invalid-punct-ident-3.rs
+++ b/src/test/ui/proc-macro/invalid-punct-ident-3.rs
@@ -3,6 +3,11 @@
 // FIXME https://github.com/rust-lang/rust/issues/59998
 // normalize-stderr-test "thread.*panicked.*proc_macro_server.rs.*\n" -> ""
 // normalize-stderr-test "note:.*RUST_BACKTRACE=1.*\n" -> ""
+// normalize-stderr-test "\nerror: internal compiler error.*\n\n" -> ""
+// normalize-stderr-test "note:.*unexpectedly panicked.*\n\n" -> ""
+// normalize-stderr-test "note: we would appreciate a bug report.*\n\n" -> ""
+// normalize-stderr-test "note: compiler flags.*\n\n" -> ""
+// normalize-stderr-test "note: rustc.*running on.*\n\n" -> ""
 
 #[macro_use]
 extern crate invalid_punct_ident;
diff --git a/src/test/ui/proc-macro/invalid-punct-ident-3.stderr b/src/test/ui/proc-macro/invalid-punct-ident-3.stderr
index a5e5ded6533..6044b988740 100644
--- a/src/test/ui/proc-macro/invalid-punct-ident-3.stderr
+++ b/src/test/ui/proc-macro/invalid-punct-ident-3.stderr
@@ -1,5 +1,5 @@
 error: proc macro panicked
-  --> $DIR/invalid-punct-ident-3.rs:10:1
+  --> $DIR/invalid-punct-ident-3.rs:15:1
    |
 LL | invalid_raw_ident!();
    | ^^^^^^^^^^^^^^^^^^^^^