Change the default math class of U+22A5 ⊥ UP TACK to Normal (#5714)

Cargo.lock

@@ -3106,6 +3106,7 @@ dependencies = [
  "rayon",
  "siphasher 1.0.1",
  "thin-vec",
+ "unicode-math-class",
 ]
 
 [[package]]

crates/typst-layout/src/math/fragment.rs

@@ -13,6 +13,7 @@ use typst_library::math::{EquationElem, MathSize};
 use typst_library::text::{Font, Glyph, Lang, Region, TextElem, TextItem};
 use typst_library::visualize::Paint;
 use typst_syntax::Span;
+use typst_utils::default_math_class;
 use unicode_math_class::MathClass;
 
 use super::{stretch_glyph, MathContext, Scaled};
@@ -275,11 +276,7 @@ impl GlyphFragment {
         span: Span,
     ) -> Self {
         let class = EquationElem::class_in(styles)
-            .or_else(|| match c {
-                ':' => Some(MathClass::Relation),
-                '.' | '/' | '⋯' | '⋱' | '⋰' | '⋮' => Some(MathClass::Normal),
-                _ => unicode_math_class::class(c),
-            })
+            .or_else(|| default_math_class(c))
             .unwrap_or(MathClass::Normal);
 
         let mut fragment = Self {
@@ -629,7 +626,7 @@ pub enum Limits {
 impl Limits {
     /// The default limit configuration if the given character is the base.
     pub fn for_char(c: char) -> Self {
-        match unicode_math_class::class(c) {
+        match default_math_class(c) {
             Some(MathClass::Large) => {
                 if is_integral_char(c) {
                     Limits::Never

crates/typst-library/src/math/matrix.rs

@@ -1,6 +1,6 @@
 use smallvec::{smallvec, SmallVec};
 use typst_syntax::Spanned;
-use typst_utils::Numeric;
+use typst_utils::{default_math_class, Numeric};
 use unicode_math_class::MathClass;
 
 use crate::diag::{bail, At, HintedStrResult, StrResult};
@@ -292,7 +292,7 @@ impl Delimiter {
 
     pub fn char(c: char) -> StrResult<Self> {
         if !matches!(
-            unicode_math_class::class(c),
+            default_math_class(c),
             Some(MathClass::Opening | MathClass::Closing | MathClass::Fence),
         ) {
             bail!("invalid delimiter: \"{}\"", c)
@@ -311,7 +311,7 @@ impl Delimiter {
             Some(']') => Self(Some('[')),
             Some('{') => Self(Some('}')),
             Some('}') => Self(Some('{')),
-            Some(c) => match unicode_math_class::class(c) {
+            Some(c) => match default_math_class(c) {
                 Some(MathClass::Opening) => Self(char::from_u32(c as u32 + 1)),
                 Some(MathClass::Closing) => Self(char::from_u32(c as u32 - 1)),
                 _ => Self(Some(c)),

crates/typst-syntax/src/parser.rs

@@ -3,6 +3,7 @@ use std::mem;
 use std::ops::{Index, IndexMut, Range};
 
 use ecow::{eco_format, EcoString};
+use typst_utils::default_math_class;
 use unicode_math_class::MathClass;
 
 use crate::set::{syntax_set, SyntaxSet};
@@ -468,7 +469,7 @@ fn math_class(text: &str) -> Option<MathClass> {
     chars
         .next()
         .filter(|_| chars.next().is_none())
-        .and_then(unicode_math_class::class)
+        .and_then(default_math_class)
 }
 
 /// Parse an argument list in math: `(a, b; c, d; size: #50%)`.

crates/typst-utils/Cargo.toml

@@ -18,6 +18,7 @@ portable-atomic = { workspace = true }
 rayon = { workspace = true }
 siphasher = { workspace = true }
 thin-vec = { workspace = true }
+unicode-math-class = { workspace = true }
 
 [lints]
 workspace = true

crates/typst-utils/src/lib.rs

@@ -31,6 +31,7 @@ use std::ops::{Add, Deref, Div, Mul, Neg, Sub};
 use std::sync::Arc;
 
 use siphasher::sip128::{Hasher128, SipHasher13};
+use unicode_math_class::MathClass;
 
 /// Turn a closure into a struct implementing [`Debug`].
 pub fn debug<F>(f: F) -> impl Debug
@@ -337,3 +338,28 @@ pub trait Numeric:
     /// Whether `self` consists only of finite parts.
     fn is_finite(self) -> bool;
 }
+
+/// Returns the default math class of a character in Typst, if it has one.
+///
+/// This is determined by the Unicode math class, with some manual overrides.
+pub fn default_math_class(c: char) -> Option<MathClass> {
+    match c {
+        // Better spacing.
+        // https://github.com/typst/typst/commit/2e039cb052fcb768027053cbf02ce396f6d7a6be
+        ':' => Some(MathClass::Relation),
+
+        // Better spacing when used alongside + PLUS SIGN.
+        // https://github.com/typst/typst/pull/1726
+        '⋯' | '⋱' | '⋰' | '⋮' => Some(MathClass::Normal),
+
+        // Better spacing.
+        // https://github.com/typst/typst/pull/1855
+        '.' | '/' => Some(MathClass::Normal),
+
+        // ⊥ UP TACK should not be a relation, contrary to ⟂ PERPENDICULAR.
+        // https://github.com/typst/typst/pull/5714
+        '\u{22A5}' => Some(MathClass::Normal),
+
+        c => unicode_math_class::class(c),
+    }
+}

tests/suite/math/class.typ

@@ -45,3 +45,8 @@ $class("large", ->)_a$
 
 $limits(class("normal", ->))_a$
 $ scripts(class("relation", x))_a $
+
+--- issue-4985-up-tack-is-normal-perp-is-relation ---
+$ top = 1 \
+  bot = 2 \
+  a perp b $