Handle panic runtime specially

compiler/rustc_metadata/src/dependency_format.rs

@@ -366,14 +366,19 @@ fn verify_ok(tcx: TyCtxt<'_>, list: &[Linkage]) {
                     prev_name, cur_name
                 ));
             }
-            panic_runtime = Some((cnum, tcx.panic_strategy(cnum).unwrap()));
+            panic_runtime = Some((
+                cnum,
+                tcx.panic_strategy(cnum).unwrap_or_else(|| {
+                    bug!("cannot determine panic strategy of a panic runtime");
+                }),
+            ));
         }
     }
 
     // If we found a panic runtime, then we know by this point that it's the
     // only one, but we perform validation here that all the panic strategy
     // compilation modes for the whole DAG are valid.
-    if let Some((cnum, found_strategy)) = panic_runtime {
+    if let Some((runtime_cnum, found_strategy)) = panic_runtime {
         let desired_strategy = sess.panic_strategy();
 
         // First up, validate that our selected panic runtime is indeed exactly
@@ -383,7 +388,7 @@ fn verify_ok(tcx: TyCtxt<'_>, list: &[Linkage]) {
                 "the linked panic runtime `{}` is \
                                not compiled with this crate's \
                                panic strategy `{}`",
-                tcx.crate_name(cnum),
+                tcx.crate_name(runtime_cnum),
                 desired_strategy.desc()
             ));
         }
@@ -397,7 +402,7 @@ fn verify_ok(tcx: TyCtxt<'_>, list: &[Linkage]) {
                 continue;
             }
             let cnum = CrateNum::new(i + 1);
-            if tcx.is_compiler_builtins(cnum) {
+            if cnum == runtime_cnum || tcx.is_compiler_builtins(cnum) {
                 continue;
             }
 

compiler/rustc_mir_transform/src/ffi_unwind_calls.rs

@@ -1,5 +1,5 @@
 use rustc_hir::def::DefKind;
-use rustc_hir::def_id::LocalDefId;
+use rustc_hir::def_id::{LocalDefId, LOCAL_CRATE};
 use rustc_middle::mir::*;
 use rustc_middle::ty::layout;
 use rustc_middle::ty::query::Providers;
@@ -129,6 +129,10 @@ fn has_ffi_unwind_calls(tcx: TyCtxt<'_>, local_def_id: LocalDefId) -> bool {
 }
 
 fn required_panic_strategy(tcx: TyCtxt<'_>, (): ()) -> Option<PanicStrategy> {
+    if tcx.is_panic_runtime(LOCAL_CRATE) {
+        return Some(tcx.sess.panic_strategy());
+    }
+
     if tcx.sess.panic_strategy() == PanicStrategy::Abort {
         return Some(PanicStrategy::Abort);
     }

src/test/ui/panic-runtime/transitive-link-a-bunch.stderr

@@ -2,9 +2,7 @@ error: cannot link together two panic runtimes: panic_runtime_unwind and panic_r
 
 error: the linked panic runtime `panic_runtime_abort` is not compiled with this crate's panic strategy `unwind`
 
-error: the crate `wants_panic_runtime_abort` is compiled with the panic strategy `abort` which is incompatible with this crate's strategy of `unwind`
+error: the crate `wants_panic_runtime_abort` requires panic strategy `abort` which is incompatible with this crate's strategy of `unwind`
 
-error: the crate `panic_runtime_abort` is compiled with the panic strategy `abort` which is incompatible with this crate's strategy of `unwind`
-
-error: aborting due to 4 previous errors
+error: aborting due to 3 previous errors
 

src/test/ui/panic-runtime/want-unwind-got-abort.rs

@@ -1,6 +1,6 @@
 // build-fail
 // needs-unwind
-// error-pattern:is incompatible with this crate's strategy of `unwind`
+// error-pattern:is not compiled with this crate's panic strategy `unwind`
 // aux-build:panic-runtime-abort.rs
 // aux-build:panic-runtime-lang-items.rs
 // ignore-wasm32-bare compiled with panic=abort by default

src/test/ui/panic-runtime/want-unwind-got-abort.stderr

@@ -1,6 +1,4 @@
 error: the linked panic runtime `panic_runtime_abort` is not compiled with this crate's panic strategy `unwind`
 
-error: the crate `panic_runtime_abort` is compiled with the panic strategy `abort` which is incompatible with this crate's strategy of `unwind`
-
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 

src/test/ui/panic-runtime/want-unwind-got-abort2.stderr

@@ -1,8 +1,6 @@
 error: the linked panic runtime `panic_runtime_abort` is not compiled with this crate's panic strategy `unwind`
 
-error: the crate `wants_panic_runtime_abort` is compiled with the panic strategy `abort` which is incompatible with this crate's strategy of `unwind`
+error: the crate `wants_panic_runtime_abort` requires panic strategy `abort` which is incompatible with this crate's strategy of `unwind`
 
-error: the crate `panic_runtime_abort` is compiled with the panic strategy `abort` which is incompatible with this crate's strategy of `unwind`
-
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors