Decimal formatting for some floating point numbers does not round-to-even

I have discovered a class of f64 for which format!("{}", f) rounds ties up to 3, rather than down to 2 as expected. Formatting those same numbers with fixed precision correctly rounds ties to even.

Here is some code that demonstrates the discrepancy:

fn main() {
    let fs: [f64; 15] = [
        112171935477118.12,
        181681934355391.62,
        -581170764721946.2,
        131673329546813.62,
        711901304153173.2,
        91266877191838.12,
        18406814307348.312,
        -620793498637746.2,
        -889345962364809.2,
        -664193405104534.2,
        -157386457699813.12,
        566922914748074.2,
        223437609802779.12,
        945017102864441.2,
        32461450983719.062,
    ];

    for f in fs {
        let no_precision = format!("{}", f);
        let mut split = no_precision.split('.');
        let _int = split.next();
        let frac = split.next().unwrap();
        let precision = frac.len();
        println!("{} != {:.2$}", f, f, precision);
    }

This program prints:

112171935477118.13 != 112171935477118.12
181681934355391.63 != 181681934355391.62
-581170764721946.3 != -581170764721946.2
131673329546813.63 != 131673329546813.62
711901304153173.3 != 711901304153173.2
91266877191838.13 != 91266877191838.12
18406814307348.313 != 18406814307348.312
-620793498637746.3 != -620793498637746.2
-889345962364809.3 != -889345962364809.2
-664193405104534.3 != -664193405104534.2
-157386457699813.13 != -157386457699813.12
566922914748074.3 != 566922914748074.2
223437609802779.13 != 223437609802779.12
945017102864441.3 != 945017102864441.2
32461450983719.063 != 32461450983719.062

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rustc --version --verbose:

rustc 1.83.0-nightly (2bd1e894e 2024-09-26)
binary: rustc
commit-hash: 2bd1e894efde3b6be857ad345914a3b1cea51def
commit-date: 2024-09-26
host: x86_64-unknown-linux-gnu
release: 1.83.0-nightly
LLVM version: 19.1.0

Start by compiling and running the supplied Rust reproducer with the reported rustc version, comparing format!("{}", f) with the fixed-precision formatting. Trace the floating-point Display formatting entry point and its rounding behavior for the listed f64 values. Done means default formatting rounds these ties to even consistently with fixed precision, with regression coverage for the demonstrated cases.