Fix f-string regression

Author: Charles Marsh

parser/src/fstring.rs

@@ -4,6 +4,7 @@ use crate::{
     error::{FStringError, FStringErrorType, ParseError},
     parser::parse_expression,
 };
+use itertools::Itertools;
 use std::{iter, mem, str};
 
 struct FStringParser<'a> {
@@ -105,13 +106,16 @@ impl<'a> FStringParser<'a> {
                                 nested -= 1;
                                 if nested == 0 {
                                     formatted_value_piece.push(next);
-                                    spec_constructor.extend(
-                                        FStringParser::new(
-                                            &format!("{{{}}}", formatted_value_piece),
-                                            Location::default(),
-                                            &self.recurse_lvl + 1,
-                                        )
-                                        .parse()?,
+                                    let values = FStringParser::new(
+                                        &formatted_value_piece,
+                                        Location::default(),
+                                        &self.recurse_lvl + 1,
+                                    )
+                                    .parse()?;
+                                    spec_constructor.push(values
+                                        .into_iter()
+                                        .exactly_one()
+                                        .expect("Expected formatted value to produce exactly one expression.")
                                     );
                                     formatted_value_piece.clear();
                                 } else {

parser/src/snapshots/rustpython_parser__fstring__tests__fstring_parse_selfdocumenting_base.snap

@@ -1,5 +1,5 @@
 ---
-source: parser/src/fstring.rs
+source: compiler/parser/src/fstring.rs
 expression: parse_ast
 ---
 [

parser/src/snapshots/rustpython_parser__fstring__tests__fstring_parse_selfdocumenting_base_more.snap

@@ -1,5 +1,5 @@
 ---
-source: parser/src/fstring.rs
+source: compiler/parser/src/fstring.rs
 expression: parse_ast
 ---
 [

parser/src/snapshots/rustpython_parser__fstring__tests__fstring_parse_selfdocumenting_format.snap

@@ -1,5 +1,5 @@
 ---
-source: parser/src/fstring.rs
+source: compiler/parser/src/fstring.rs
 expression: parse_ast
 ---
 [

parser/src/snapshots/rustpython_parser__fstring__tests__parse_empty_fstring.snap

@@ -1,5 +1,5 @@
 ---
-source: parser/src/fstring.rs
+source: compiler/parser/src/fstring.rs
 expression: "parse_fstring(\"\").unwrap()"
 ---
 []

parser/src/snapshots/rustpython_parser__fstring__tests__parse_fstring.snap

@@ -1,5 +1,5 @@
 ---
-source: parser/src/fstring.rs
+source: compiler/parser/src/fstring.rs
 expression: parse_ast
 ---
 [

parser/src/snapshots/rustpython_parser__fstring__tests__parse_fstring_equals.snap

@@ -1,5 +1,5 @@
 ---
-source: parser/src/fstring.rs
+source: compiler/parser/src/fstring.rs
 expression: parse_ast
 ---
 [

parser/src/snapshots/rustpython_parser__fstring__tests__parse_fstring_nested_spec.snap

@@ -1,5 +1,5 @@
 ---
-source: parser/src/fstring.rs
+source: compiler/parser/src/fstring.rs
 expression: parse_ast
 ---
 [
@@ -37,11 +37,20 @@ expression: parse_ast
                                     column: 0,
                                 },
                                 custom: (),
-                                node: Constant {
-                                    value: Str(
-                                        "{ spec}",
-                                    ),
-                                    kind: None,
+                                node: FormattedValue {
+                                    value: Located {
+                                        location: Location {
+                                            row: 1,
+                                            column: 3,
+                                        },
+                                        custom: (),
+                                        node: Name {
+                                            id: "spec",
+                                            ctx: Load,
+                                        },
+                                    },
+                                    conversion: 0,
+                                    format_spec: None,
                                 },
                             },
                         ],

parser/src/snapshots/rustpython_parser__fstring__tests__parse_fstring_not_equals.snap

@@ -1,5 +1,5 @@
 ---
-source: parser/src/fstring.rs
+source: compiler/parser/src/fstring.rs
 expression: parse_ast
 ---
 [

parser/src/snapshots/rustpython_parser__fstring__tests__parse_fstring_not_nested_spec.snap

@@ -1,5 +1,5 @@
 ---
-source: parser/src/fstring.rs
+source: compiler/parser/src/fstring.rs
 expression: parse_ast
 ---
 [