Auto merge of #4588 - phansch:add_custom_ice_hook, r=Manishearth

Add custom ICE message that points to Clippy repo

changelog: Link to Clippy issue tracker in ICE messages

This utilizes https://github.com/rust-lang/rust/pull/60584 by setting
our own `panic_hook` and pointing to our own issue tracker instead of
the rustc issue tracker.

This also adds a new internal lint to test the ICE message.

**Potential downsides**

* This essentially copies rustc's `report_ice` function as
  `report_clippy_ice`. I think that's how it's meant to be implemented, but
  maybe @jonas-schievink could have a look as well =)

  The downside of more-or-less copying this function is that we have to
  maintain it as well now.
  The original function can be found [here][original].
* `driver` now depends directly on `rustc` and `rustc_errors`

Closes #2734

[original]: https://github.com/rust-lang/rust/blob/59367b074f1523353dddefa678ffe3cac9fd4e50/src/librustc_driver/lib.rs#L1185

2 files changed, 41 insertions, 0 deletions

diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
index 07fe9f47465..c1113daadd8 100644
--- a/clippy_lints/src/lib.rs
+++ b/clippy_lints/src/lib.rs
@@ -963,6 +963,7 @@ pub fn register_plugins(store: &mut lint::LintStore, sess: &Session, conf: &Conf
     let array_size_threshold = conf.array_size_threshold;
     store.register_late_pass(move || box large_stack_arrays::LargeStackArrays::new(array_size_threshold));
     store.register_early_pass(|| box as_conversions::AsConversions);
+    store.register_early_pass(|| box utils::internal_lints::ProduceIce);
 
     store.register_group(true, "clippy::restriction", Some("clippy_restriction"), vec![
         LintId::of(&arithmetic::FLOAT_ARITHMETIC),
@@ -1057,6 +1058,7 @@ pub fn register_plugins(store: &mut lint::LintStore, sess: &Session, conf: &Conf
         LintId::of(&utils::internal_lints::COMPILER_LINT_FUNCTIONS),
         LintId::of(&utils::internal_lints::LINT_WITHOUT_LINT_PASS),
         LintId::of(&utils::internal_lints::OUTER_EXPN_EXPN_DATA),
+        LintId::of(&utils::internal_lints::PRODUCE_ICE),
     ]);
 
     store.register_group(true, "clippy::all", Some("clippy"), vec![
diff --git a/clippy_lints/src/utils/internal_lints.rs b/clippy_lints/src/utils/internal_lints.rs
index 5bf10558221..ea7ea5818cd 100644
--- a/clippy_lints/src/utils/internal_lints.rs
+++ b/clippy_lints/src/utils/internal_lints.rs
@@ -11,8 +11,10 @@ use rustc::lint::{EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintAr
 use rustc::{declare_lint_pass, declare_tool_lint, impl_lint_pass};
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_errors::Applicability;
+use syntax::ast;
 use syntax::ast::{Crate as AstCrate, ItemKind, Name};
 use syntax::source_map::Span;
+use syntax::visit::FnKind;
 use syntax_pos::symbol::SymbolStr;
 
 declare_clippy_lint! {
@@ -99,6 +101,24 @@ declare_clippy_lint! {
     "using `cx.outer_expn().expn_data()` instead of `cx.outer_expn_data()`"
 }
 
+declare_clippy_lint! {
+    /// **What it does:** Not an actual lint. This lint is only meant for testing our customized internal compiler
+    /// error message by calling `panic`.
+    ///
+    /// **Why is this bad?** ICE in large quantities can damage your teeth
+    ///
+    /// **Known problems:** None
+    ///
+    /// **Example:**
+    /// Bad:
+    /// ```rust,ignore
+    /// 🍦🍦🍦🍦🍦
+    /// ```
+    pub PRODUCE_ICE,
+    internal,
+    "this message should not appear anywhere as we ICE before and don't emit the lint"
+}
+
 declare_lint_pass!(ClippyLintsInternal => [CLIPPY_LINTS_INTERNAL]);
 
 impl EarlyLintPass for ClippyLintsInternal {
@@ -302,3 +322,22 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for OuterExpnDataPass {
         }
     }
 }
+
+declare_lint_pass!(ProduceIce => [PRODUCE_ICE]);
+
+impl EarlyLintPass for ProduceIce {
+    fn check_fn(&mut self, _: &EarlyContext<'_>, fn_kind: FnKind<'_>, _: &ast::FnDecl, _: Span, _: ast::NodeId) {
+        if is_trigger_fn(fn_kind) {
+            panic!("Testing the ICE message");
+        }
+    }
+}
+
+fn is_trigger_fn(fn_kind: FnKind<'_>) -> bool {
+    match fn_kind {
+        FnKind::ItemFn(ident, ..) | FnKind::Method(ident, ..) => {
+            ident.name.as_str() == "it_looks_like_you_are_trying_to_kill_clippy"
+        },
+        FnKind::Closure(..) => false,
+    }
+}