Rollup merge of rust-lang#89500 - FabianWolff:issue-87308, r=petroche…

…nkov

Fix ICE with buffered lint referring to AST node deleted by everybody_loops

Fixes rust-lang#87308. Note the following comment:
https://github.com/rust-lang/rust/blob/08759c691e2e9799a3c6780ffdf910240ebd4a6b/compiler/rustc_lint/src/early.rs#L415-L417

As it turns out, this is not _always_ a bug, because `-Zunpretty=everybody_loops` causes a lot of AST nodes to be deleted, and thus some buffered lints will refer to non-existent node ids. To fix this, my changes simply ignore buffered lints if `-Zunpretty=everybody_loops` is enabled, which, from my understanding, shouldn't be a big issue because it only affects pretty-printing. Of course, a more elegant solution would only ignore buffered lints that actually point at deleted node ids, but I haven't figured out an easy way of achieving this.

For the concrete example in rust-lang#87308, the buffered lint is created [here](https://github.com/rust-lang/rust/blob/08759c691e2e9799a3c6780ffdf910240ebd4a6b/compiler/rustc_expand/src/mbe/macro_rules.rs#L145-L151) with the `lint_node_id` from [here](https://github.com/rust-lang/rust/blob/08759c691e2e9799a3c6780ffdf910240ebd4a6b/compiler/rustc_expand/src/mbe/macro_rules.rs#L319), i.e. it points at the macro _expansion_, which then gets deleted by `ReplaceBodyWithLoop` [here](https://github.com/rust-lang/rust/blob/08759c691e2e9799a3c6780ffdf910240ebd4a6b/compiler/rustc_interface/src/passes.rs#L377).

compiler/rustc_interface/src/passes.rs

@@ -437,12 +437,18 @@ pub fn configure_and_expand(
     });
 
     // Add all buffered lints from the `ParseSess` to the `Session`.
-    sess.parse_sess.buffered_lints.with_lock(|buffered_lints| {
-        info!("{} parse sess buffered_lints", buffered_lints.len());
-        for early_lint in buffered_lints.drain(..) {
-            resolver.lint_buffer().add_early_lint(early_lint);
-        }
-    });
+    // The ReplaceBodyWithLoop pass may have deleted some AST nodes, potentially
+    // causing a delay_span_bug later if a buffered lint refers to such a deleted
+    // AST node (issue #87308). Since everybody_loops is for pretty-printing only,
+    // anyway, we simply skip all buffered lints here.
+    if !matches!(sess.opts.pretty, Some(PpMode::Source(PpSourceMode::EveryBodyLoops))) {
+        sess.parse_sess.buffered_lints.with_lock(|buffered_lints| {
+            info!("{} parse sess buffered_lints", buffered_lints.len());
+            for early_lint in buffered_lints.drain(..) {
+                resolver.lint_buffer().add_early_lint(early_lint);
+            }
+        });
+    }
 
     Ok(krate)
 }

src/test/ui/lint/issue-87308.rs

@@ -0,0 +1,12 @@
+// Regression test for issue #87308.
+
+// compile-flags: -Zunpretty=everybody_loops
+// check-pass
+
+macro_rules! foo {
+    () => { break 'x; }
+}
+
+pub fn main() {
+    'x: loop { foo!() }
+}

src/test/ui/lint/issue-87308.stdout

@@ -0,0 +1,14 @@
+#![feature(prelude_import)]
+#![no_std]
+#[prelude_import]
+use ::std::prelude::rust_2015::*;
+#[macro_use]
+extern crate std;
+// Regression test for issue #87308.
+
+// compile-flags: -Zunpretty=everybody_loops
+// check-pass
+
+macro_rules! foo { () => { break 'x ; } }
+
+pub fn main() { loop { } }