Add diagnostic for filter_map followed by next

crates/hir/src/diagnostics.rs

@@ -5,5 +5,14 @@ pub use hir_expand::diagnostics::{
 };
 pub use hir_ty::diagnostics::{
     IncorrectCase, MismatchedArgCount, MissingFields, MissingMatchArms, MissingOkOrSomeInTailExpr,
-    NoSuchField, RemoveThisSemicolon,
+    NoSuchField, RemoveThisSemicolon, ReplaceFilterMapNextWithFindMap,
 };
+
+// PHIL:
+// hir/src/diagnostics.rs - just pub uses the type from hir_ty::diagnostics (DONE)
+// hir_ty/src/diagnostics.rs - defines the type (DONE)
+// hir_ty/src/diagnostics.rs - plus a test (DONE) <--- one example found, need to copy the not-applicable tests from the assist version
+// ide/src/diagnostics.rs - define handler for when this diagnostic is raised (DONE)
+
+// ide/src/diagnostics/fixes.rs - pulls in type from hir, and impls DiagnosticWithFix (TODO)
+// hir_ty/src/diagnostics/expr.rs - do the real work (TODO)