Auto merge of #119606 - nnethercote:consuming-emit, r=oli-obk

Consuming `emit`

This PR makes `DiagnosticBuilder::emit` consuming, i.e. take `self` instead of `&mut self`. This is good because it doesn't make sense to emit a diagnostic twice.

This requires some changes to `DiagnosticBuilder` method changing -- every existing non-consuming chaining method gets a new consuming partner with a `_mv` suffix -- but permits a host of beneficial follow-up changes: more concise code through more chaining, removal of redundant diagnostic construction API methods, and removal of machinery to track the possibility of a diagnostic being emitted multiple times.

r? `@compiler-errors`

Author: bors

clippy_config/src/msrvs.rs

@@ -109,7 +109,7 @@ impl Msrv {
             if let Some(duplicate) = msrv_attrs.last() {
                 sess.dcx()
                     .struct_span_err(duplicate.span, "`clippy::msrv` is defined multiple times")
-                    .span_note(msrv_attr.span, "first definition found here")
+                    .span_note_mv(msrv_attr.span, "first definition found here")
                     .emit();
             }
 

clippy_utils/src/attrs.rs

@@ -136,7 +136,7 @@ pub fn get_unique_attr<'a>(
         if let Some(duplicate) = unique_attr {
             sess.dcx()
                 .struct_span_err(attr.span, format!("`{name}` is defined multiple times"))
-                .span_note(duplicate.span, "first definition found here")
+                .span_note_mv(duplicate.span, "first definition found here")
                 .emit();
         } else {
             unique_attr = Some(attr);