mir_transform: implement forced inlining

Adds `#[rustc_force_inline]` which is similar to always inlining but
reports an error if the inlining was not possible, and which always
attempts to inline annotated items, regardless of optimisation levels.
It can only be applied to free functions to guarantee that the MIR
inliner will be able to resolve calls.

1 files changed, 18 insertions, 0 deletions

diff --git a/compiler/rustc_passes/src/errors.rs b/compiler/rustc_passes/src/errors.rs
index d95fa5db0ce..13da021c614 100644
--- a/compiler/rustc_passes/src/errors.rs
+++ b/compiler/rustc_passes/src/errors.rs
@@ -689,6 +689,24 @@ pub(crate) struct RustcPubTransparent {
 }
 
 #[derive(Diagnostic)]
+#[diag(passes_rustc_force_inline)]
+pub(crate) struct RustcForceInline {
+    #[primary_span]
+    pub attr_span: Span,
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(passes_rustc_force_inline_coro)]
+pub(crate) struct RustcForceInlineCoro {
+    #[primary_span]
+    pub attr_span: Span,
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
 #[diag(passes_link_ordinal)]
 pub(crate) struct LinkOrdinal {
     #[primary_span]