From 1b9fed83974b8e300ad2286c54eb3a00b78aa1c5 Mon Sep 17 00:00:00 2001
From: Tom Kuson <mail@tjkuson.me>
Date: Tue, 8 Aug 2023 21:51:37 +0100
Subject: [PATCH] Error on zero tab width (#6429)

## Summary

Error if `tab-size` is set to zero (it is used as a divisor). Closes
#6423.

Also fixes a typo.

## Test Plan

Running ruff with a config

```toml
[tool.ruff]
tab-size = 0
```

returns an error message to the user saying that `tab-size` must be
greater than zero.
---
 crates/ruff/src/line_width.rs            | 23 ++++++++++++-----------
 crates/ruff/src/message/text.rs          |  4 +---
 crates/ruff/src/rules/pycodestyle/mod.rs |  3 ++-
 crates/ruff/src/settings/options.rs      |  4 ++--
 crates/ruff_cache/src/cache_key.rs       |  8 ++++++++
 ruff.schema.json                         |  4 ++--
 6 files changed, 27 insertions(+), 19 deletions(-)

diff --git a/crates/ruff/src/line_width.rs b/crates/ruff/src/line_width.rs
index 8619b42aa3..a3db08416c 100644
--- a/crates/ruff/src/line_width.rs
+++ b/crates/ruff/src/line_width.rs
@@ -1,4 +1,5 @@
 use serde::{Deserialize, Serialize};
+use std::num::NonZeroU8;
 use unicode_width::UnicodeWidthChar;
 
 use ruff_macros::CacheKey;
@@ -83,7 +84,7 @@ impl LineWidth {
     }
 
     fn update(mut self, chars: impl Iterator<Item = char>) -> Self {
-        let tab_size: usize = self.tab_size.into();
+        let tab_size: usize = self.tab_size.as_usize();
         for c in chars {
             match c {
                 '\t' => {
@@ -144,22 +145,22 @@ impl PartialOrd<LineLength> for LineWidth {
 /// The size of a tab.
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize, CacheKey)]
 #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
-pub struct TabSize(pub u8);
+pub struct TabSize(pub NonZeroU8);
+
+impl TabSize {
+    fn as_usize(self) -> usize {
+        self.0.get() as usize
+    }
+}
 
 impl Default for TabSize {
     fn default() -> Self {
-        Self(4)
+        Self(NonZeroU8::new(4).unwrap())
     }
 }
 
-impl From<u8> for TabSize {
-    fn from(tab_size: u8) -> Self {
+impl From<NonZeroU8> for TabSize {
+    fn from(tab_size: NonZeroU8) -> Self {
         Self(tab_size)
     }
 }
-
-impl From<TabSize> for usize {
-    fn from(tab_size: TabSize) -> Self {
-        tab_size.0 as usize
-    }
-}
diff --git a/crates/ruff/src/message/text.rs b/crates/ruff/src/message/text.rs
index 3aa5ebc545..31bbb614d6 100644
--- a/crates/ruff/src/message/text.rs
+++ b/crates/ruff/src/message/text.rs
@@ -293,12 +293,10 @@ impl Display for MessageCodeFrame<'_> {
 }
 
 fn replace_whitespace(source: &str, annotation_range: TextRange) -> SourceCode {
-    static TAB_SIZE: TabSize = TabSize(4); // TODO(jonathan): use `tab-size`
-
     let mut result = String::new();
     let mut last_end = 0;
     let mut range = annotation_range;
-    let mut line_width = LineWidth::new(TAB_SIZE);
+    let mut line_width = LineWidth::new(TabSize::default());
 
     for (index, c) in source.char_indices() {
         let old_width = line_width.get();
diff --git a/crates/ruff/src/rules/pycodestyle/mod.rs b/crates/ruff/src/rules/pycodestyle/mod.rs
index 9810feb01c..86eb5925c6 100644
--- a/crates/ruff/src/rules/pycodestyle/mod.rs
+++ b/crates/ruff/src/rules/pycodestyle/mod.rs
@@ -6,6 +6,7 @@ pub(crate) mod helpers;
 
 #[cfg(test)]
 mod tests {
+    use std::num::NonZeroU8;
     use std::path::Path;
 
     use anyhow::Result;
@@ -204,7 +205,7 @@ mod tests {
         let diagnostics = test_path(
             Path::new("pycodestyle/E501_2.py"),
             &settings::Settings {
-                tab_size: tab_size.into(),
+                tab_size: NonZeroU8::new(tab_size).unwrap().into(),
                 ..settings::Settings::for_rule(Rule::LineTooLong)
             },
         )?;
diff --git a/crates/ruff/src/settings/options.rs b/crates/ruff/src/settings/options.rs
index 5e3ea14207..43d3618d77 100644
--- a/crates/ruff/src/settings/options.rs
+++ b/crates/ruff/src/settings/options.rs
@@ -312,13 +312,13 @@ pub struct Options {
         "#
     )]
     /// The line length to use when enforcing long-lines violations (like
-    /// `E501`).
+    /// `E501`). Must be greater than `0`.
     pub line_length: Option<LineLength>,
     #[option(
         default = "4",
         value_type = "int",
         example = r#"
-            tab_size = 8
+            tab-size = 8
         "#
     )]
     /// The tabulation size to calculate line length.
diff --git a/crates/ruff_cache/src/cache_key.rs b/crates/ruff_cache/src/cache_key.rs
index e015112bda..c62e580d1e 100644
--- a/crates/ruff_cache/src/cache_key.rs
+++ b/crates/ruff_cache/src/cache_key.rs
@@ -2,6 +2,7 @@ use std::borrow::Cow;
 use std::collections::hash_map::DefaultHasher;
 use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};
 use std::hash::{Hash, Hasher};
+use std::num::NonZeroU8;
 use std::ops::{Deref, DerefMut};
 use std::path::{Path, PathBuf};
 
@@ -205,6 +206,13 @@ impl CacheKey for i8 {
     }
 }
 
+impl CacheKey for NonZeroU8 {
+    #[inline]
+    fn cache_key(&self, state: &mut CacheKeyHasher) {
+        state.write_u8(self.get());
+    }
+}
+
 macro_rules! impl_cache_key_tuple {
     () => (
         impl CacheKey for () {
diff --git a/ruff.schema.json b/ruff.schema.json
index 2c5bfc3090..9d47d617dc 100644
--- a/ruff.schema.json
+++ b/ruff.schema.json
@@ -376,7 +376,7 @@
       ]
     },
     "line-length": {
-      "description": "The line length to use when enforcing long-lines violations (like `E501`).",
+      "description": "The line length to use when enforcing long-lines violations (like `E501`). Must be greater than `0`.",
       "anyOf": [
         {
           "$ref": "#/definitions/LineLength"
@@ -2741,7 +2741,7 @@
       "description": "The size of a tab.",
       "type": "integer",
       "format": "uint8",
-      "minimum": 0.0
+      "minimum": 1.0
     },
     "Version": {
       "type": "string"