Auto merge of #106537 - fmease:recover-where-clause-before-tuple-struct-body, r=estebank

Recover from where clauses placed before tuple struct bodies

Open to any suggestions regarding the phrasing of the diagnostic.

Fixes #100790.
`@rustbot` label A-diagnostics
r? diagnostics

compiler/rustc_parse/src/errors.rs

@@ -1255,3 +1255,27 @@ pub(crate) struct ExpectedFnPathFoundFnKeyword {
     #[suggestion(applicability = "machine-applicable", code = "Fn", style = "verbose")]
     pub fn_token_span: Span,
 }
+
+#[derive(Diagnostic)]
+#[diag(parse_where_clause_before_tuple_struct_body)]
+pub(crate) struct WhereClauseBeforeTupleStructBody {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+    #[label(name_label)]
+    pub name: Span,
+    #[label(body_label)]
+    pub body: Span,
+    #[subdiagnostic]
+    pub sugg: Option<WhereClauseBeforeTupleStructBodySugg>,
+}
+
+#[derive(Subdiagnostic)]
+#[multipart_suggestion(suggestion, applicability = "machine-applicable")]
+pub(crate) struct WhereClauseBeforeTupleStructBodySugg {
+    #[suggestion_part(code = "{snippet}")]
+    pub left: Span,
+    pub snippet: String,
+    #[suggestion_part(code = "")]
+    pub right: Span,
+}