Avoid parsing f-strings in type annotations (#3699)

crates/ruff/resources/test/fixtures/pyflakes/F821_14.py

@@ -0,0 +1,7 @@
+"""Test case: f-strings in type annotations."""
+
+from typing import List
+
+x = 1
+
+x: List[f"i{x}nt"] = []

crates/ruff/resources/test/fixtures/pyflakes/F821_15.py

@@ -0,0 +1,9 @@
+"""Test case: f-strings in future type annotations."""
+
+from __future__ import annotations
+
+from typing import List
+
+x = 1
+
+x: List[f"i{x}nt"] = []

crates/ruff/src/checkers/ast/mod.rs

@@ -2130,7 +2130,8 @@ where
     }
 
     fn visit_expr(&mut self, expr: &'b Expr) {
-        if !self.ctx.in_deferred_type_definition
+        if !self.ctx.in_f_string
+            && !self.ctx.in_deferred_type_definition
             && self.ctx.in_deferred_string_type_definition.is_none()
             && self.ctx.in_type_definition
             && self.ctx.annotations_future_enabled
@@ -3283,7 +3284,7 @@ where
                 value: Constant::Str(value),
                 kind,
             } => {
-                if self.ctx.in_type_definition && !self.ctx.in_literal {
+                if self.ctx.in_type_definition && !self.ctx.in_literal && !self.ctx.in_f_string {
                     self.deferred.string_type_definitions.push((
                         Range::from(expr),
                         value,
@@ -3624,7 +3625,10 @@ where
                 self.ctx.in_subscript = prev_in_subscript;
             }
             ExprKind::JoinedStr { .. } => {
+                let prev_in_f_string = self.ctx.in_f_string;
+                self.ctx.in_f_string = true;
                 visitor::walk_expr(self, expr);
+                self.ctx.in_f_string = prev_in_f_string;
             }
             _ => visitor::walk_expr(self, expr),
         }

crates/ruff/src/rules/pyflakes/mod.rs

@@ -108,6 +108,8 @@ mod tests {
     #[test_case(Rule::UndefinedName, Path::new("F821_11.py"); "F821_11")]
     #[test_case(Rule::UndefinedName, Path::new("F821_12.py"); "F821_12")]
     #[test_case(Rule::UndefinedName, Path::new("F821_13.py"); "F821_13")]
+    #[test_case(Rule::UndefinedName, Path::new("F821_14.py"); "F821_14")]
+    #[test_case(Rule::UndefinedName, Path::new("F821_15.py"); "F821_15")]
     #[test_case(Rule::UndefinedExport, Path::new("F822_0.py"); "F822_0")]
     #[test_case(Rule::UndefinedExport, Path::new("F822_1.py"); "F822_1")]
     #[test_case(Rule::UndefinedExport, Path::new("F822_2.py"); "F822_2")]

crates/ruff/src/rules/pyflakes/snapshots/ruff__rules__pyflakes__tests__F821_F821_14.py.snap

@@ -0,0 +1,6 @@
+---
+source: crates/ruff/src/rules/pyflakes/mod.rs
+expression: diagnostics
+---
+[]
+

crates/ruff/src/rules/pyflakes/snapshots/ruff__rules__pyflakes__tests__F821_F821_15.py.snap

@@ -0,0 +1,6 @@
+---
+source: crates/ruff/src/rules/pyflakes/mod.rs
+expression: diagnostics
+---
+[]
+

crates/ruff_python_ast/src/context.rs

@@ -45,6 +45,7 @@ pub struct Context<'a> {
     pub in_deferred_string_type_definition: Option<AnnotationKind>,
     pub in_deferred_type_definition: bool,
     pub in_exception_handler: bool,
+    pub in_f_string: bool,
     pub in_literal: bool,
     pub in_subscript: bool,
     pub in_type_checking_block: bool,
@@ -83,6 +84,7 @@ impl<'a> Context<'a> {
             in_deferred_string_type_definition: None,
             in_deferred_type_definition: false,
             in_exception_handler: false,
+            in_f_string: false,
             in_literal: false,
             in_subscript: false,
             in_type_checking_block: false,