Remove redundant completions

2 files changed, 37 insertions, 4 deletions

diff --git a/crates/ide/src/completion/completion_context.rs b/crates/ide/src/completion/completion_context.rs
index 8dea8a4bf..c9473cca6 100644
--- a/crates/ide/src/completion/completion_context.rs
+++ b/crates/ide/src/completion/completion_context.rs
@@ -16,10 +16,10 @@ use crate::{
     call_info::ActiveParameter,
     completion::{
         patterns::{
-            has_bind_pat_parent, has_block_expr_parent, has_field_list_parent,
-            has_impl_as_prev_sibling, has_impl_parent, has_item_list_or_source_file_parent,
-            has_ref_parent, has_trait_as_prev_sibling, has_trait_parent, if_is_prev,
-            is_in_loop_body, is_match_arm, unsafe_is_prev,
+            fn_is_prev, for_is_prev2, has_bind_pat_parent, has_block_expr_parent,
+            has_field_list_parent, has_impl_as_prev_sibling, has_impl_parent,
+            has_item_list_or_source_file_parent, has_ref_parent, has_trait_as_prev_sibling,
+            has_trait_parent, if_is_prev, is_in_loop_body, is_match_arm, unsafe_is_prev,
         },
         CompletionConfig,
     },
@@ -91,6 +91,8 @@ pub(crate) struct CompletionContext<'a> {
     pub(super) impl_as_prev_sibling: bool,
     pub(super) is_match_arm: bool,
     pub(super) has_item_list_or_source_file_parent: bool,
+    pub(super) for_is_prev2: bool,
+    pub(super) fn_is_prev: bool,
     pub(super) locals: Vec<(String, Local)>,
 }
 
@@ -174,6 +176,8 @@ impl<'a> CompletionContext<'a> {
             if_is_prev: false,
             is_match_arm: false,
             has_item_list_or_source_file_parent: false,
+            for_is_prev2: false,
+            fn_is_prev: false,
             locals,
         };
 
@@ -221,6 +225,14 @@ impl<'a> CompletionContext<'a> {
         Some(ctx)
     }
 
+    /// Checks whether completions in that particular case don't make much sense.
+    /// Examples:
+    /// - `fn <|>` -- we expect function name, it's unlikely that "hint" will be helpful.
+    /// - `for _ i<|>` -- obviously, it'll be "in" keyword.
+    pub(crate) fn no_completion_required(&self) -> bool {
+        self.fn_is_prev || self.for_is_prev2
+    }
+
     /// The range of the identifier that is being completed.
     pub(crate) fn source_range(&self) -> TextRange {
         // check kind of macro-expanded token, but use range of original token
@@ -253,6 +265,8 @@ impl<'a> CompletionContext<'a> {
         self.mod_declaration_under_caret =
             find_node_at_offset::<ast::Module>(&file_with_fake_ident, offset)
                 .filter(|module| module.item_list().is_none());
+        self.for_is_prev2 = for_is_prev2(syntax_element.clone());
+        self.fn_is_prev = fn_is_prev(syntax_element.clone());
     }
 
     fn fill(
diff --git a/crates/ide/src/completion/patterns.rs b/crates/ide/src/completion/patterns.rs
index b17ddf133..76fcad631 100644
--- a/crates/ide/src/completion/patterns.rs
+++ b/crates/ide/src/completion/patterns.rs
@@ -116,6 +116,25 @@ pub(crate) fn if_is_prev(element: SyntaxElement) -> bool {
         .is_some()
 }
 
+pub(crate) fn fn_is_prev(element: SyntaxElement) -> bool {
+    element
+        .into_token()
+        .and_then(|it| previous_non_trivia_token(it))
+        .filter(|it| it.kind() == FN_KW)
+        .is_some()
+}
+
+/// Check if the token previous to the previous one is `for`.
+/// For example, `for _ i<|>` => true.
+pub(crate) fn for_is_prev2(element: SyntaxElement) -> bool {
+    element
+        .into_token()
+        .and_then(|it| previous_non_trivia_token(it))
+        .and_then(|it| previous_non_trivia_token(it))
+        .filter(|it| it.kind() == FOR_KW)
+        .is_some()
+}
+
 #[test]
 fn test_if_is_prev() {
     check_pattern_is_applicable(r"if l<|>", if_is_prev);