From 883a07fb7bf6ac5c8354d2c25a3d97b7d5374823 Mon Sep 17 00:00:00 2001
From: NetterSilver <133535268+Silvertree2010@users.noreply.github.com>
Date: Thu, 15 Oct 2026 17:31:12 +0200
Subject: [PATCH] Keep nan/inf time and fraction look-alikes as text

Found while testing crates/core/src/parse.rs:~170 (parse_time, parts parsed with f64::parse)

Co-Authored-By: Claude Haiku 5.5 <noreply@anthropic.com>
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
---
 crates/core/src/parse.rs | 33 +++++++++++++++++++++++++++------
 1 file changed, 27 insertions(+), 6 deletions(-)

diff --git a/crates/core/src/parse.rs b/crates/core/src/parse.rs
index b465beaf9..f525b7966 100644
--- a/crates/core/src/parse.rs
+++ b/crates/core/src/parse.rs
@@ -146,14 +146,28 @@ fn parse_plain(t: &str) -> Option<(f64, Option<&'static str>)> {
     Some((n, fmt))
 }
 
+/// A plain ASCII number: digits, with an optional `.digits` fraction when `frac` is set. Rejects
+/// `nan`, `inf`, signs and exponents that `f64::from_str` would accept.
+fn plain_number(s: &str, frac: bool) -> Option<f64> {
+    let (int, dec) = match s.split_once('.') {
+        Some((i, d)) if frac => (i, Some(d)),
+        _ => (s, None),
+    };
+    let digits = |x: &str| !x.is_empty() && x.bytes().all(|c| c.is_ascii_digit());
+    if !digits(int) || dec.is_some_and(|d| !digits(d)) {
+        return None;
+    }
+    s.parse().ok()
+}
+
 /// `1/2` (only with a whole part, else it's a date), `1 1/2`, `0 3/4`.
 fn parse_fraction(t: &str) -> Option<f64> {
     let (whole, frac) = t.split_once(' ')?;
     let neg = whole.starts_with('-');
-    let w: f64 = whole.trim_start_matches('-').parse().ok()?;
+    let w = plain_number(whole.trim_start_matches('-'), false)?;
     let (a, b) = frac.trim().split_once('/')?;
-    let a: f64 = a.parse().ok()?;
-    let b: f64 = b.parse().ok()?;
+    let a = plain_number(a, false)?;
+    let b = plain_number(b, false)?;
     if b == 0.0 || !w.is_finite() {
         return None;
     }
@@ -187,9 +201,9 @@ fn parse_time(t: &str) -> Option<(f64, bool, bool)> {
     if parts.len() > 3 || parts.iter().any(|p| p.is_empty()) {
         return None;
     }
-    let mut h: f64 = parts.first()?.parse().ok()?;
-    let m: f64 = parts.get(1).map_or(Some(0.0), |p| p.parse().ok())?;
-    let s: f64 = parts.get(2).map_or(Some(0.0), |p| p.parse().ok())?;
+    let mut h = plain_number(parts.first()?, false)?;
+    let m = parts.get(1).map_or(Some(0.0), |p| plain_number(p, false))?;
+    let s = parts.get(2).map_or(Some(0.0), |p| plain_number(p, true))?;
     if m >= 60.0 || s >= 60.0 || h < 0.0 || m < 0.0 || s < 0.0 {
         return None;
     }
@@ -326,6 +340,13 @@ mod tests {
         parse_input(s, DateSystem::D1900)
     }
 
+    #[test]
+    fn non_digit_time_and_fraction_parts_stay_text() {
+        for s in ["1:nan", "nan:30", "1:30:NaN", "1 nan/2", "1 1/nan", "inf:00", "1e1:00", "+5:00"] {
+            assert_eq!(p(s).value, Value::text(s), "{s}");
+        }
+    }
+
     #[test]
     fn month_name_short_year() {
         for s in ["Mar 4, 26", "Mar 4 26", "March 4 26", "4 March 26", "Mar 4, 2026"] {