[refurb] Implement fstring-number-format (FURB116)

crates/ruff_linter/resources/test/fixtures/refurb/FURB116.py

@@ -0,0 +1,19 @@
+num = 1337
+
+def return_num() -> int:
+    return num
+
+print(oct(num)[2:])  # FURB116
+print(hex(num)[2:])  # FURB116
+print(bin(num)[2:])  # FURB116
+
+print(oct(1337)[2:])  # FURB116
+print(hex(1337)[2:])  # FURB116
+print(bin(1337)[2:])  # FURB116
+
+print(bin(return_num())[2:])  # FURB116 (no autofix)
+print(bin(int(f"{num}"))[2:])  # FURB116 (no autofix)
+
+## invalid
+print(oct(0o1337)[1:])
+print(hex(0x1337)[3:])

crates/ruff_linter/src/checkers/ast/analyze/expression.rs

@@ -128,6 +128,9 @@ pub(crate) fn expression(expr: &Expr, checker: &mut Checker) {
             if checker.enabled(Rule::SortedMinMax) {
                 refurb::rules::sorted_min_max(checker, subscript);
             }
+            if checker.enabled(Rule::FStringNumberFormat) {
+                refurb::rules::fstring_number_format(checker, subscript);
+            }
 
             pandas_vet::rules::subscript(checker, value, expr);
         }

crates/ruff_linter/src/codes.rs

@@ -1050,6 +1050,7 @@ pub fn code_to_rule(linter: Linter, code: &str) -> Option<(RuleGroup, Rule)> {
         (Refurb, "110") => (RuleGroup::Preview, rules::refurb::rules::IfExpInsteadOfOrOperator),
         #[allow(deprecated)]
         (Refurb, "113") => (RuleGroup::Nursery, rules::refurb::rules::RepeatedAppend),
+        (Refurb, "116") => (RuleGroup::Preview, rules::refurb::rules::FStringNumberFormat),
         (Refurb, "118") => (RuleGroup::Preview, rules::refurb::rules::ReimplementedOperator),
         (Refurb, "129") => (RuleGroup::Preview, rules::refurb::rules::ReadlinesInFor),
         #[allow(deprecated)]

crates/ruff_linter/src/rules/refurb/mod.rs

@@ -42,6 +42,7 @@ mod tests {
     #[test_case(Rule::HashlibDigestHex, Path::new("FURB181.py"))]
     #[test_case(Rule::ListReverseCopy, Path::new("FURB187.py"))]
     #[test_case(Rule::WriteWholeFile, Path::new("FURB103.py"))]
+    #[test_case(Rule::FStringNumberFormat, Path::new("FURB116.py"))]
     #[test_case(Rule::SortedMinMax, Path::new("FURB192.py"))]
     fn rules(rule_code: Rule, path: &Path) -> Result<()> {
         let snapshot = format!("{}_{}", rule_code.noqa_code(), path.to_string_lossy());

crates/ruff_linter/src/rules/refurb/rules/fstring_number_format.rs

@@ -0,0 +1,181 @@
+use ruff_diagnostics::{Diagnostic, Edit, Fix, FixAvailability, Violation};
+use ruff_macros::{derive_message_formats, violation};
+use ruff_python_ast::{self as ast, Expr, ExprCall};
+use ruff_text_size::Ranged;
+
+use crate::checkers::ast::Checker;
+use crate::fix::snippet::SourceCodeSnippet;
+
+/// ## What it does
+/// Checks for uses of `bin(...)[2:]` (or `hex`, or `oct`) to convert
+/// an integer into a string.
+///
+/// ## Why is this bad?
+/// When converting an integer to a baseless binary, hexadecimal, or octal
+/// string, using f-strings is more concise and readable than using the
+/// `bin`, `hex`, or `oct` functions followed by a slice.
+///
+/// ## Example
+/// ```python
+/// print(bin(1337)[2:])
+/// ```
+///
+/// Use instead:
+/// ```python
+/// print(f"{1337:b}")
+/// ```
+#[violation]
+pub struct FStringNumberFormat {
+    replacement: Option<SourceCodeSnippet>,
+    base: Base,
+}
+
+impl Violation for FStringNumberFormat {
+    const FIX_AVAILABILITY: FixAvailability = FixAvailability::Sometimes;
+
+    #[derive_message_formats]
+    fn message(&self) -> String {
+        let FStringNumberFormat { replacement, base } = self;
+        let function_name = base.function_name();
+
+        if let Some(display) = replacement
+            .as_ref()
+            .and_then(SourceCodeSnippet::full_display)
+        {
+            format!("Replace `{function_name}` call with `{display}`")
+        } else {
+            format!("Replace `{function_name}` call with f-string")
+        }
+    }
+
+    fn fix_title(&self) -> Option<String> {
+        let FStringNumberFormat { replacement, .. } = self;
+        if let Some(display) = replacement
+            .as_ref()
+            .and_then(SourceCodeSnippet::full_display)
+        {
+            Some(format!("Replace with `{display}`"))
+        } else {
+            Some(format!("Replace with f-string"))
+        }
+    }
+}
+
+/// FURB116
+pub(crate) fn fstring_number_format(checker: &mut Checker, subscript: &ast::ExprSubscript) {
+    // The slice must be exactly `[2:]`.
+    let Expr::Slice(ast::ExprSlice {
+        lower: Some(lower),
+        upper: None,
+        step: None,
+        ..
+    }) = subscript.slice.as_ref()
+    else {
+        return;
+    };
+
+    let Expr::NumberLiteral(ast::ExprNumberLiteral {
+        value: ast::Number::Int(int),
+        ..
+    }) = lower.as_ref()
+    else {
+        return;
+    };
+
+    if *int != 2 {
+        return;
+    }
+
+    // The call must be exactly `hex(...)`, `bin(...)`, or `oct(...)`.
+    let Expr::Call(ExprCall {
+        func, arguments, ..
+    }) = subscript.value.as_ref()
+    else {
+        return;
+    };
+
+    if !arguments.keywords.is_empty() {
+        return;
+    }
+
+    let [arg] = &*arguments.args else {
+        return;
+    };
+
+    let Some(id) = checker.semantic().resolve_builtin_symbol(func) else {
+        return;
+    };
+
+    let Some(base) = Base::from_str(id) else {
+        return;
+    };
+
+    // Generate a replacement, if possible.
+    let replacement = if matches!(
+        arg,
+        Expr::NumberLiteral(_) | Expr::Name(_) | Expr::Attribute(_)
+    ) {
+        let inner_source = checker.locator().slice(arg);
+
+        let quote = checker.stylist().quote();
+        let shorthand = base.shorthand();
+
+        Some(format!("f{quote}{{{inner_source}:{shorthand}}}{quote}"))
+    } else {
+        None
+    };
+
+    let mut diagnostic = Diagnostic::new(
+        FStringNumberFormat {
+            replacement: replacement.as_deref().map(SourceCodeSnippet::from_str),
+            base,
+        },
+        subscript.range(),
+    );
+
+    if let Some(replacement) = replacement {
+        diagnostic.set_fix(Fix::safe_edit(Edit::range_replacement(
+            replacement,
+            subscript.range(),
+        )));
+    }
+
+    checker.diagnostics.push(diagnostic);
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+enum Base {
+    Hex,
+    Bin,
+    Oct,
+}
+
+impl Base {
+    /// Returns the shorthand for the base.
+    fn shorthand(self) -> &'static str {
+        match self {
+            Base::Hex => "x",
+            Base::Bin => "b",
+            Base::Oct => "o",
+        }
+    }
+
+    /// Returns the builtin function name for the base.
+    fn function_name(self) -> &'static str {
+        match self {
+            Base::Hex => "hex",
+            Base::Bin => "bin",
+            Base::Oct => "oct",
+        }
+    }
+
+    /// Parses the base from a string.
+    fn from_str(s: &str) -> Option<Self> {
+        match s {
+            "hex" => Some(Base::Hex),
+            "bin" => Some(Base::Bin),
+            "oct" => Some(Base::Oct),
+            _ => None,
+        }
+    }
+}

crates/ruff_linter/src/rules/refurb/rules/mod.rs

@@ -2,6 +2,7 @@ pub(crate) use bit_count::*;
 pub(crate) use check_and_remove_from_set::*;
 pub(crate) use delete_full_slice::*;
 pub(crate) use for_loop_set_mutations::*;
+pub(crate) use fstring_number_format::*;
 pub(crate) use hashlib_digest_hex::*;
 pub(crate) use if_exp_instead_of_or_operator::*;
 pub(crate) use if_expr_min_max::*;
@@ -32,6 +33,7 @@ mod bit_count;
 mod check_and_remove_from_set;
 mod delete_full_slice;
 mod for_loop_set_mutations;
+mod fstring_number_format;
 mod hashlib_digest_hex;
 mod if_exp_instead_of_or_operator;
 mod if_expr_min_max;

crates/ruff_linter/src/rules/refurb/snapshots/ruff_linter__rules__refurb__tests__FURB116_FURB116.py.snap

@@ -0,0 +1,144 @@
+---
+source: crates/ruff_linter/src/rules/refurb/mod.rs
+---
+FURB116.py:6:7: FURB116 [*] Replace `oct` call with `f"{num:o}"`
+  |
+4 |     return num
+5 | 
+6 | print(oct(num)[2:])  # FURB116
+  |       ^^^^^^^^^^^^ FURB116
+7 | print(hex(num)[2:])  # FURB116
+8 | print(bin(num)[2:])  # FURB116
+  |
+  = help: Replace with `f"{num:o}"`
+
+ℹ Safe fix
+3 3 | def return_num() -> int:
+4 4 |     return num
+5 5 | 
+6   |-print(oct(num)[2:])  # FURB116
+  6 |+print(f"{num:o}")  # FURB116
+7 7 | print(hex(num)[2:])  # FURB116
+8 8 | print(bin(num)[2:])  # FURB116
+9 9 | 
+
+FURB116.py:7:7: FURB116 [*] Replace `hex` call with `f"{num:x}"`
+  |
+6 | print(oct(num)[2:])  # FURB116
+7 | print(hex(num)[2:])  # FURB116
+  |       ^^^^^^^^^^^^ FURB116
+8 | print(bin(num)[2:])  # FURB116
+  |
+  = help: Replace with `f"{num:x}"`
+
+ℹ Safe fix
+4 4 |     return num
+5 5 | 
+6 6 | print(oct(num)[2:])  # FURB116
+7   |-print(hex(num)[2:])  # FURB116
+  7 |+print(f"{num:x}")  # FURB116
+8 8 | print(bin(num)[2:])  # FURB116
+9 9 | 
+10 10 | print(oct(1337)[2:])  # FURB116
+
+FURB116.py:8:7: FURB116 [*] Replace `bin` call with `f"{num:b}"`
+   |
+ 6 | print(oct(num)[2:])  # FURB116
+ 7 | print(hex(num)[2:])  # FURB116
+ 8 | print(bin(num)[2:])  # FURB116
+   |       ^^^^^^^^^^^^ FURB116
+ 9 | 
+10 | print(oct(1337)[2:])  # FURB116
+   |
+   = help: Replace with `f"{num:b}"`
+
+ℹ Safe fix
+5 5 | 
+6 6 | print(oct(num)[2:])  # FURB116
+7 7 | print(hex(num)[2:])  # FURB116
+8   |-print(bin(num)[2:])  # FURB116
+  8 |+print(f"{num:b}")  # FURB116
+9 9 | 
+10 10 | print(oct(1337)[2:])  # FURB116
+11 11 | print(hex(1337)[2:])  # FURB116
+
+FURB116.py:10:7: FURB116 [*] Replace `oct` call with `f"{1337:o}"`
+   |
+ 8 | print(bin(num)[2:])  # FURB116
+ 9 | 
+10 | print(oct(1337)[2:])  # FURB116
+   |       ^^^^^^^^^^^^^ FURB116
+11 | print(hex(1337)[2:])  # FURB116
+12 | print(bin(1337)[2:])  # FURB116
+   |
+   = help: Replace with `f"{1337:o}"`
+
+ℹ Safe fix
+7  7  | print(hex(num)[2:])  # FURB116
+8  8  | print(bin(num)[2:])  # FURB116
+9  9  | 
+10    |-print(oct(1337)[2:])  # FURB116
+   10 |+print(f"{1337:o}")  # FURB116
+11 11 | print(hex(1337)[2:])  # FURB116
+12 12 | print(bin(1337)[2:])  # FURB116
+13 13 | 
+
+FURB116.py:11:7: FURB116 [*] Replace `hex` call with `f"{1337:x}"`
+   |
+10 | print(oct(1337)[2:])  # FURB116
+11 | print(hex(1337)[2:])  # FURB116
+   |       ^^^^^^^^^^^^^ FURB116
+12 | print(bin(1337)[2:])  # FURB116
+   |
+   = help: Replace with `f"{1337:x}"`
+
+ℹ Safe fix
+8  8  | print(bin(num)[2:])  # FURB116
+9  9  | 
+10 10 | print(oct(1337)[2:])  # FURB116
+11    |-print(hex(1337)[2:])  # FURB116
+   11 |+print(f"{1337:x}")  # FURB116
+12 12 | print(bin(1337)[2:])  # FURB116
+13 13 | 
+14 14 | print(bin(return_num())[2:])  # FURB116 (no autofix)
+
+FURB116.py:12:7: FURB116 [*] Replace `bin` call with `f"{1337:b}"`
+   |
+10 | print(oct(1337)[2:])  # FURB116
+11 | print(hex(1337)[2:])  # FURB116
+12 | print(bin(1337)[2:])  # FURB116
+   |       ^^^^^^^^^^^^^ FURB116
+13 | 
+14 | print(bin(return_num())[2:])  # FURB116 (no autofix)
+   |
+   = help: Replace with `f"{1337:b}"`
+
+ℹ Safe fix
+9  9  | 
+10 10 | print(oct(1337)[2:])  # FURB116
+11 11 | print(hex(1337)[2:])  # FURB116
+12    |-print(bin(1337)[2:])  # FURB116
+   12 |+print(f"{1337:b}")  # FURB116
+13 13 | 
+14 14 | print(bin(return_num())[2:])  # FURB116 (no autofix)
+15 15 | print(bin(int(f"{num}"))[2:])  # FURB116 (no autofix)
+
+FURB116.py:14:7: FURB116 Replace `bin` call with f-string
+   |
+12 | print(bin(1337)[2:])  # FURB116
+13 | 
+14 | print(bin(return_num())[2:])  # FURB116 (no autofix)
+   |       ^^^^^^^^^^^^^^^^^^^^^ FURB116
+15 | print(bin(int(f"{num}"))[2:])  # FURB116 (no autofix)
+   |
+   = help: Replace with f-string
+
+FURB116.py:15:7: FURB116 Replace `bin` call with f-string
+   |
+14 | print(bin(return_num())[2:])  # FURB116 (no autofix)
+15 | print(bin(int(f"{num}"))[2:])  # FURB116 (no autofix)
+   |       ^^^^^^^^^^^^^^^^^^^^^^ FURB116
+16 | 
+17 | ## invalid
+   |
+   = help: Replace with f-string