Rollup merge of rust-lang#93024 - compiler-errors:inline-mir-bad-bounds, r=estebank

Do not ICE when inlining a function with un-satisfiable bounds

Fixes rust-lang#93008
This is kinda a hack... but it's the fix I thought had the least blast-radius.

We use `normalize_param_env_or_error` to verify that the predicates in the param env are self-consistent, since with RevealAll, a bad predicate like `<&'static () as Clone>` will be evaluated with an empty ParamEnv (since it references no generics), and we'll raise an error for it.

Author: matthiaskrgr

compiler/rustc_mir_transform/src/inline.rs

@@ -7,6 +7,7 @@ use rustc_index::vec::Idx;
 use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
 use rustc_middle::mir::visit::*;
 use rustc_middle::mir::*;
+use rustc_middle::traits::ObligationCause;
 use rustc_middle::ty::subst::Subst;
 use rustc_middle::ty::{self, ConstKind, Instance, InstanceDef, ParamEnv, Ty, TyCtxt};
 use rustc_span::{hygiene::ExpnKind, ExpnData, Span};
@@ -75,10 +76,18 @@ fn inline<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) -> bool {
         return false;
     }
 
+    let param_env = tcx.param_env_reveal_all_normalized(def_id);
+    let param_env = rustc_trait_selection::traits::normalize_param_env_or_error(
+        tcx,
+        def_id,
+        param_env,
+        ObligationCause::misc(body.span, hir_id),
+    );
+
     let mut this = Inliner {
         tcx,
-        param_env: tcx.param_env_reveal_all_normalized(body.source.def_id()),
-        codegen_fn_attrs: tcx.codegen_fn_attrs(body.source.def_id()),
+        param_env,
+        codegen_fn_attrs: tcx.codegen_fn_attrs(def_id),
         hir_id,
         history: Vec::new(),
         changed: false,

compiler/rustc_trait_selection/src/traits/codegen.rs

@@ -64,6 +64,8 @@ pub fn codegen_fulfill_obligation<'tcx>(
             Err(Unimplemented) => {
                 // This can trigger when we probe for the source of a `'static` lifetime requirement
                 // on a trait object: `impl Foo for dyn Trait {}` has an implicit `'static` bound.
+                // This can also trigger when we have a global bound that is not actually satisfied,
+                // but was included during typeck due to the trivial_bounds feature.
                 infcx.tcx.sess.delay_span_bug(
                     rustc_span::DUMMY_SP,
                     &format!(

src/test/ui/trait-bounds/issue-93008.rs

@@ -0,0 +1,10 @@
+// compile-flags: -Zmir-opt-level=4
+
+pub fn bar<T>(s: &'static mut ())
+where
+    &'static mut (): Clone, //~ ERROR the trait bound
+{
+    <&'static mut () as Clone>::clone(&s);
+}
+
+fn main() {}

src/test/ui/trait-bounds/issue-93008.stderr

@@ -0,0 +1,12 @@
+error[E0277]: the trait bound `&'static mut (): Clone` is not satisfied
+  --> $DIR/issue-93008.rs:5:5
+   |
+LL |     &'static mut (): Clone,
+   |     ^^^^^^^^^^^^^^^^^^^^^^ the trait `Clone` is not implemented for `&'static mut ()`
+   |
+   = help: see issue #48214
+   = help: add `#![feature(trivial_bounds)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.