From 1316422a7c2ef26e9da78fa23f170407b1cb39bb Mon Sep 17 00:00:00 2001
From: Phil Ellison <phil.j.ellison@gmail.com>
Date: Mon, 28 Dec 2020 13:41:15 +0000
Subject: Add diagnostic for filter_map followed by next

---
 crates/ide/src/diagnostics/fixes.rs | 33 ++++++++++++++++++++++++++++++++-
 1 file changed, 32 insertions(+), 1 deletion(-)

(limited to 'crates/ide/src/diagnostics')

diff --git a/crates/ide/src/diagnostics/fixes.rs b/crates/ide/src/diagnostics/fixes.rs
index 579d5a308..eafbac43a 100644
--- a/crates/ide/src/diagnostics/fixes.rs
+++ b/crates/ide/src/diagnostics/fixes.rs
@@ -4,7 +4,7 @@ use hir::{
     db::AstDatabase,
     diagnostics::{
         Diagnostic, IncorrectCase, MissingFields, MissingOkOrSomeInTailExpr, NoSuchField,
-        RemoveThisSemicolon, UnresolvedModule,
+        RemoveThisSemicolon, ReplaceFilterMapNextWithFindMap, UnresolvedModule,
     },
     HasSource, HirDisplay, InFile, Semantics, VariantDef,
 };
@@ -144,6 +144,37 @@ impl DiagnosticWithFix for IncorrectCase {
     }
 }
 
+// Bugs:
+//  * Action is applicable for both iter() and filter_map() rows
+//  * Action deletes the entire method chain
+impl DiagnosticWithFix for ReplaceFilterMapNextWithFindMap {
+    fn fix(&self, sema: &Semantics<RootDatabase>) -> Option<Fix> {
+        let root = sema.db.parse_or_expand(self.file)?;
+
+        let next_expr = self.next_expr.to_node(&root);
+        let next_expr_range = next_expr.syntax().text_range();
+
+        let filter_map_expr = self.filter_map_expr.to_node(&root);
+        let filter_map_expr_range = filter_map_expr.syntax().text_range();
+
+        let edit = TextEdit::delete(next_expr_range);
+
+        // This is the entire method chain, including the array literal
+        eprintln!("NEXT EXPR: {:#?}", next_expr);
+        // This is the entire method chain except for the final next()
+        eprintln!("FILTER MAP EXPR: {:#?}", filter_map_expr);
+
+        let source_change =
+            SourceFileEdit { file_id: self.file.original_file(sema.db), edit }.into();
+
+        Some(Fix::new(
+            "Replace filter_map(..).next() with find_map()",
+            source_change,
+            filter_map_expr_range,
+        ))
+    }
+}
+
 fn missing_record_expr_field_fix(
     sema: &Semantics<RootDatabase>,
     usage_file_id: FileId,
-- 
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