Auto merge of #101558 - JhonnyBillM:session-diagnostic-to-diagnostic-handler-refactor, r=davidtwco

Move and rename `SessionDiagnostic` & `SessionSubdiagnostic` traits and macros

After PR #101434, we want to:
- [x] Move `SessionDiagnostic` to `rustc_errors`.
- [x] Add `emit_` methods that accept `impl SessionDiagnostic` to `Handler`.
- [x] _(optional)_ Rename trait `SessionDiagnostic` to `DiagnosticHandler`.
- [x] _(optional)_ Rename macro `SessionDiagnostic` to `DiagnosticHandler`.
- [x] Update Rustc Dev Guide and Docs to reflect these changes. https://github.com/rust-lang/rustc-dev-guide/pull/1460

Now I am having build issues getting the compiler to build when trying to rename the macro.

<details>
  <summary>See diagnostics errors and context when building.</summary>

```
error: diagnostics should only be created in `SessionDiagnostic`/`AddSubdiagnostic` impls
  --> compiler/rustc_attr/src/session_diagnostics.rs:13:10
   |
13 |   #[derive(DiagnosticHandler)]
   |            ^^^^^^^^^^^^^^^^^ in this derive macro expansion
   |
  ::: /Users/jhonny/.cargo/registry/src/github.com-1ecc6299db9ec823/synstructure-0.12.6/src/macros.rs:94:9
   |
94 | /         pub fn $derives(
95 | |             i: $crate::macros::TokenStream
96 | |         ) -> $crate::macros::TokenStream {
   | |________________________________________- in this expansion of `#[derive(DiagnosticHandler)]`
   |
note: the lint level is defined here
  --> compiler/rustc_attr/src/lib.rs:10:9
   |
10 | #![deny(rustc::diagnostic_outside_of_impl)]
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

```

And also this one:

```
error: diagnostics should only be created in `SessionDiagnostic`/`AddSubdiagnostic` impls
   --> compiler/rustc_attr/src/session_diagnostics.rs:213:32
    |
213 |         let mut diag = handler.struct_span_err_with_code(
    |                                ^^^^^^^^^^^^^^^^^^^^^^^^^
```

> **Note**
> Can't find where this message is coming from, because you can see in [this experimental branch](https://github.com/JhonnyBillM/rust/tree/experimental/trying-to-rename-session-diagnostic-macro)  that I updated all errors and diags to say:
> error: diagnostics should only be created in **`DiagnosticHandler`**/`AddSubdiagnostic` impls
> and not:
> error: diagnostics should only be created in **`SessionDiagnostic`**/`AddSubdiagnostic` impls

</details>

I tried building the compiler in different ways (playing with the stages etc), but nothing worked.

## Question

**Do we need to build or do something different when renaming a macro and identifiers?**

For context, see experimental commit https://github.com/JhonnyBillM/rust/commit/f2193a98b44db3f2af77a878824b152cdf0d34a5 where the macro and symbols are renamed, but it doesn't compile.

1 files changed, 22 insertions, 22 deletions

diff --git a/compiler/rustc_const_eval/src/errors.rs b/compiler/rustc_const_eval/src/errors.rs
index c3547cb3abd..c6cb7a8b961 100644
--- a/compiler/rustc_const_eval/src/errors.rs
+++ b/compiler/rustc_const_eval/src/errors.rs
@@ -1,8 +1,8 @@
 use rustc_hir::ConstContext;
-use rustc_macros::SessionDiagnostic;
+use rustc_macros::Diagnostic;
 use rustc_span::Span;
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(const_eval::unstable_in_stable)]
 pub(crate) struct UnstableInStable {
     pub gate: String,
@@ -21,14 +21,14 @@ pub(crate) struct UnstableInStable {
     pub attr_span: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(const_eval::thread_local_access, code = "E0625")]
 pub(crate) struct NonConstOpErr {
     #[primary_span]
     pub span: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(const_eval::static_access, code = "E0013")]
 #[help]
 pub(crate) struct StaticAccessErr {
@@ -40,7 +40,7 @@ pub(crate) struct StaticAccessErr {
     pub teach: Option<()>,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(const_eval::raw_ptr_to_int)]
 #[note]
 #[note(const_eval::note2)]
@@ -49,7 +49,7 @@ pub(crate) struct RawPtrToIntErr {
     pub span: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(const_eval::raw_ptr_comparison)]
 #[note]
 pub(crate) struct RawPtrComparisonErr {
@@ -57,14 +57,14 @@ pub(crate) struct RawPtrComparisonErr {
     pub span: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(const_eval::panic_non_str)]
 pub(crate) struct PanicNonStrErr {
     #[primary_span]
     pub span: Span,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(const_eval::mut_deref, code = "E0658")]
 pub(crate) struct MutDerefErr {
     #[primary_span]
@@ -72,7 +72,7 @@ pub(crate) struct MutDerefErr {
     pub kind: ConstContext,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(const_eval::transient_mut_borrow, code = "E0658")]
 pub(crate) struct TransientMutBorrowErr {
     #[primary_span]
@@ -80,7 +80,7 @@ pub(crate) struct TransientMutBorrowErr {
     pub kind: ConstContext,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(const_eval::transient_mut_borrow_raw, code = "E0658")]
 pub(crate) struct TransientMutBorrowErrRaw {
     #[primary_span]
@@ -88,7 +88,7 @@ pub(crate) struct TransientMutBorrowErrRaw {
     pub kind: ConstContext,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(const_eval::max_num_nodes_in_const)]
 pub(crate) struct MaxNumNodesInConstErr {
     #[primary_span]
@@ -96,7 +96,7 @@ pub(crate) struct MaxNumNodesInConstErr {
     pub global_const_id: String,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(const_eval::unallowed_fn_pointer_call)]
 pub(crate) struct UnallowedFnPointerCall {
     #[primary_span]
@@ -104,7 +104,7 @@ pub(crate) struct UnallowedFnPointerCall {
     pub kind: ConstContext,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(const_eval::unstable_const_fn)]
 pub(crate) struct UnstableConstFn {
     #[primary_span]
@@ -112,7 +112,7 @@ pub(crate) struct UnstableConstFn {
     pub def_path: String,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(const_eval::unallowed_mutable_refs, code = "E0764")]
 pub(crate) struct UnallowedMutableRefs {
     #[primary_span]
@@ -122,7 +122,7 @@ pub(crate) struct UnallowedMutableRefs {
     pub teach: Option<()>,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(const_eval::unallowed_mutable_refs_raw, code = "E0764")]
 pub(crate) struct UnallowedMutableRefsRaw {
     #[primary_span]
@@ -131,7 +131,7 @@ pub(crate) struct UnallowedMutableRefsRaw {
     #[note(const_eval::teach_note)]
     pub teach: Option<()>,
 }
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(const_eval::non_const_fmt_macro_call, code = "E0015")]
 pub(crate) struct NonConstFmtMacroCall {
     #[primary_span]
@@ -139,7 +139,7 @@ pub(crate) struct NonConstFmtMacroCall {
     pub kind: ConstContext,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(const_eval::non_const_fn_call, code = "E0015")]
 pub(crate) struct NonConstFnCall {
     #[primary_span]
@@ -148,7 +148,7 @@ pub(crate) struct NonConstFnCall {
     pub kind: ConstContext,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(const_eval::unallowed_op_in_const_context)]
 pub(crate) struct UnallowedOpInConstContext {
     #[primary_span]
@@ -156,7 +156,7 @@ pub(crate) struct UnallowedOpInConstContext {
     pub msg: String,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(const_eval::unallowed_heap_allocations, code = "E0010")]
 pub(crate) struct UnallowedHeapAllocations {
     #[primary_span]
@@ -167,7 +167,7 @@ pub(crate) struct UnallowedHeapAllocations {
     pub teach: Option<()>,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(const_eval::unallowed_inline_asm, code = "E0015")]
 pub(crate) struct UnallowedInlineAsm {
     #[primary_span]
@@ -175,7 +175,7 @@ pub(crate) struct UnallowedInlineAsm {
     pub kind: ConstContext,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(const_eval::interior_mutable_data_refer, code = "E0492")]
 pub(crate) struct InteriorMutableDataRefer {
     #[primary_span]
@@ -188,7 +188,7 @@ pub(crate) struct InteriorMutableDataRefer {
     pub teach: Option<()>,
 }
 
-#[derive(SessionDiagnostic)]
+#[derive(Diagnostic)]
 #[diag(const_eval::interior_mutability_borrow)]
 pub(crate) struct InteriorMutabilityBorrow {
     #[primary_span]