Rollup merge of #131802 - compiler-errors:fnonce-coverage, r=Zalathar

Dont ICE when computing coverage of synthetic async closure body

I'm not totally certain if this is *right*, but at least it doesn't ICE.

The issue is that we end up generating two MIR bodies for each async closure, since the `FnOnce` and `Fn`/`FnMut` implementations have different borrowing behavior of their captured variables. They should ideally both contribute to the coverage, since those MIR bodies are (*to the user*) the same code and should have no behavioral differences.

This PR at least suppresses the ICEs, and then I guess worst case we can fix this the right way later.

r? Zalathar or re-roll

Fixes #131190

compiler/rustc_middle/src/query/mod.rs

@@ -570,6 +570,7 @@
     /// either `#[coverage(on)]` or no coverage attribute was found.
     query coverage_attr_on(key: LocalDefId) -> bool {
         desc { |tcx| "checking for `#[coverage(..)]` on `{}`", tcx.def_path_str(key) }
+        feedable
     }
 
     /// Summarizes coverage IDs inserted by the `InstrumentCoverage` MIR pass

compiler/rustc_mir_transform/src/coroutine/by_move_body.rs

@@ -223,6 +223,7 @@ pub(crate) fn coroutine_by_move_body_def_id<'tcx>(
 
     // Inherited from the by-ref coroutine.
     body_def.codegen_fn_attrs(tcx.codegen_fn_attrs(coroutine_def_id).clone());
+    body_def.coverage_attr_on(tcx.coverage_attr_on(coroutine_def_id));
     body_def.constness(tcx.constness(coroutine_def_id));
     body_def.coroutine_kind(tcx.coroutine_kind(coroutine_def_id));
     body_def.def_ident_span(tcx.def_ident_span(coroutine_def_id));

compiler/rustc_mir_transform/src/coverage/mod.rs

@@ -524,6 +524,11 @@ fn extract_hir_info<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> ExtractedHir
     // FIXME(#79625): Consider improving MIR to provide the information needed, to avoid going back
     // to HIR for it.
 
+    // HACK: For synthetic MIR bodies (async closures), use the def id of the HIR body.
+    if tcx.is_synthetic_mir(def_id) {
+        return extract_hir_info(tcx, tcx.local_parent(def_id));
+    }
+
     let hir_node = tcx.hir_node_by_def_id(def_id);
     let fn_body_id = hir_node.body_id().expect("HIR node is a function with body");
     let hir_body = tcx.hir().body(fn_body_id);

tests/coverage/async_closure.cov-map

@@ -0,0 +1,56 @@
+Function name: async_closure::call_once::<async_closure::main::{closure#0}>
+Raw bytes (9): 0x[01, 01, 00, 01, 01, 07, 01, 00, 2c]
+Number of files: 1
+- file 0 => global file 1
+Number of expressions: 0
+Number of file 0 mappings: 1
+- Code(Counter(0)) at (prev + 7, 1) to (start + 0, 44)
+Highest counter ID seen: c0
+
+Function name: async_closure::call_once::<async_closure::main::{closure#0}>::{closure#0}
+Raw bytes (14): 0x[01, 01, 00, 02, 01, 07, 2c, 01, 0e, 05, 02, 01, 00, 02]
+Number of files: 1
+- file 0 => global file 1
+Number of expressions: 0
+Number of file 0 mappings: 2
+- Code(Counter(0)) at (prev + 7, 44) to (start + 1, 14)
+- Code(Counter(1)) at (prev + 2, 1) to (start + 0, 2)
+Highest counter ID seen: c1
+
+Function name: async_closure::main
+Raw bytes (14): 0x[01, 01, 00, 02, 01, 0b, 01, 01, 16, 01, 02, 05, 02, 02]
+Number of files: 1
+- file 0 => global file 1
+Number of expressions: 0
+Number of file 0 mappings: 2
+- Code(Counter(0)) at (prev + 11, 1) to (start + 1, 22)
+- Code(Counter(0)) at (prev + 2, 5) to (start + 2, 2)
+Highest counter ID seen: c0
+
+Function name: async_closure::main::{closure#0}
+Raw bytes (9): 0x[01, 01, 00, 01, 01, 0c, 23, 00, 24]
+Number of files: 1
+- file 0 => global file 1
+Number of expressions: 0
+Number of file 0 mappings: 1
+- Code(Counter(0)) at (prev + 12, 35) to (start + 0, 36)
+Highest counter ID seen: c0
+
+Function name: async_closure::main::{closure#0}::{closure#0}::<i16>
+Raw bytes (9): 0x[01, 01, 00, 01, 01, 0c, 22, 00, 24]
+Number of files: 1
+- file 0 => global file 1
+Number of expressions: 0
+Number of file 0 mappings: 1
+- Code(Counter(0)) at (prev + 12, 34) to (start + 0, 36)
+Highest counter ID seen: c0
+
+Function name: async_closure::main::{closure#0}::{closure#1}::<i32>
+Raw bytes (9): 0x[01, 01, 00, 01, 01, 0c, 23, 00, 24]
+Number of files: 1
+- file 0 => global file 1
+Number of expressions: 0
+Number of file 0 mappings: 1
+- Code(Counter(0)) at (prev + 12, 35) to (start + 0, 36)
+Highest counter ID seen: c0
+

tests/coverage/async_closure.coverage

@@ -0,0 +1,24 @@
+   LL|       |#![feature(async_closure)]
+   LL|       |//@ edition: 2021
+   LL|       |
+   LL|       |//@ aux-build: executor.rs
+   LL|       |extern crate executor;
+   LL|       |
+   LL|      1|async fn call_once(f: impl async FnOnce()) {
+   LL|      1|    f().await;
+   LL|      1|}
+   LL|       |
+   LL|      1|pub fn main() {
+   LL|      2|    let async_closure = async || {};
+                                               ^1
+  ------------------
+  | async_closure::main::{closure#0}:
+  |   LL|      1|    let async_closure = async || {};
+  ------------------
+  | async_closure::main::{closure#0}::{closure#1}::<i32>:
+  |   LL|      1|    let async_closure = async || {};
+  ------------------
+   LL|      1|    executor::block_on(async_closure());
+   LL|      1|    executor::block_on(call_once(async_closure));
+   LL|      1|}
+

tests/coverage/async_closure.rs

@@ -0,0 +1,15 @@
+#![feature(async_closure)]
+//@ edition: 2021
+
+//@ aux-build: executor.rs
+extern crate executor;
+
+async fn call_once(f: impl async FnOnce()) {
+    f().await;
+}
+
+pub fn main() {
+    let async_closure = async || {};
+    executor::block_on(async_closure());
+    executor::block_on(call_once(async_closure));
+}

tests/crashes/131190.rs

@@ -1,19 +0,0 @@
-//@ known-bug: #131190
-//@ compile-flags: -Cinstrument-coverage --edition=2018
-
-use std::future::Future;
-
-pub fn block_on<T>(fut: impl Future<Output = T>) -> T {}
-
-async fn call_once(f: impl async FnOnce(DropMe)) {
-    f(DropMe("world")).await;
-}
-
-struct DropMe(&'static str);
-
-pub fn main() {
-    block_on(async {
-        let async_closure = async move |a: DropMe| {};
-        call_once(async_closure).await;
-    });
-}