`assert x == y` when x and y are f32 values, failed to print different values, for `x := math.f32_from_bits(1055100473)` and `y := math.f32_from_bits(1055100475)`

[spytheman]

V version: V 0.4.11 b502d52, press to see full `v doctor` output

V full version	V 0.4.11 9f91064.b502d52
OS	linux, Ubuntu 20.04.6 LTS
Processor	4 cpus, 64bit, little endian, Intel(R) Core(TM) i3-3225 CPU @ 3.30GHz
Memory	1.21GB/15.05GB
V executable	/home/delian/v/v
V last modified time	2025-08-20 05:32:20
V home dir	OK, value: /home/delian/v
VMODULES	OK, value: /home/delian/.vmodules
VTMP	OK, value: /tmp/v_1000
Current working dir	OK, value: /home/delian/v
env VFLAGS	"-no-parallel"
Git version	git version 2.50.0
V git status	weekly.2025.34-2-gb502d522
.git/config present	true
cc version	cc (Ubuntu 10.5.0-1ubuntu1~20.04) 10.5.0
gcc version	gcc (Ubuntu 10.5.0-1ubuntu1~20.04) 10.5.0
clang version	N/A
tcc version	tcc version 0.9.28rc 2025-02-13 HEAD@f8bd136d (x86_64 Linux)
tcc git status	thirdparty-linux-amd64 696c1d84
emcc version	N/A
glibc version	ldd (Ubuntu GLIBC 2.31-0ubuntu9.18) 2.31

What did you do?
./v -g -o vdbg cmd/v && ./vdbg m.v && m

import math

found := math.f32_from_bits(1055100473)
expected := math.f32_from_bits(1055100475)
assert math.tolerance(found, expected, 0.0000002) // passes
// assert math.tolerance(found, expected, 0.0000001) // fails
assert found == expected
// The above line produces a print of:
// m.v:7: FAIL: fn main.main: assert found == expected
//    left value: found = 0.4444445
//   right value: expected = 0.4444445
// ... i.e. the printed values seem the same, which makes it very difficult
// ... to understand the diff.

What did you see?

m.v:7: FAIL: fn main.main: assert found == expected
   left value: found = 0.4444445
  right value: expected = 0.4444445
V panic: Assertion failed...
v hash: b502d52
/tmp/v_1000/m.01K33CGJ1PK9J18V4PQ7JM29KA.tmp.c:3552: at _v_panic: Backtrace
/tmp/v_1000/m.01K33CGJ1PK9J18V4PQ7JM29KA.tmp.c:5974: by main__main
/tmp/v_1000/m.01K33CGJ1PK9J18V4PQ7JM29KA.tmp.c:6001: by main

What did you expect to see?

a failed assertion, where the printed values are visibly different from each other, not the same ones

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[huly-for-github]

Connected to Huly®: V_0.6-23662

[spytheman]

This program can produce similarly failing asserts, that print same values:

import math

unbuffer_stdout()

// values of ux < 953267994 are fine (they correspond to f32 values a lot smaller than 0.0001)
for ux in 953_000_000 .. max_u32 {
	if (ux & 0x2FFFFF) == 0x2FFFFF {
		println('//// ux: ${ux:12} | ux.hex(): ${ux.hex():10} | math.f32_from_bits(ux): ${math.f32_from_bits(ux)}')
	}
	for uy in ux - 2 .. ux + 2 {
		if uy == ux {
			continue
		}
		x := math.f32_from_bits(ux)
		y := math.f32_from_bits(uy)
		if x == y {
			continue
		}
		if !math.tolerance(x, y, 0.0000002) {
			continue
		}
		sx := x.str()
		sy := y.str()
		if sx != sy {
			continue
		}
		if !math.tolerance(x, y, 0.0000001) {
			println('assert math.f32_from_bits(${ux:12}) == math.f32_from_bits(${uy:12})  // f32.str(): ${sx}')
		}
	}
}

[spytheman]

Sample output:

assert math.f32_from_bits(   953275306) == math.f32_from_bits(   953275304)  // f32.str(): 0.0001000532
assert math.f32_from_bits(   953275307) == math.f32_from_bits(   953275305)  // f32.str(): 0.0001000532
assert math.f32_from_bits(   953275308) == math.f32_from_bits(   953275306)  // f32.str(): 0.0001000532
assert math.f32_from_bits(   953275309) == math.f32_from_bits(   953275307)  // f32.str(): 0.0001000532
assert math.f32_from_bits(   953275312) == math.f32_from_bits(   953275310)  // f32.str(): 0.0001000533
assert math.f32_from_bits(   953275313) == math.f32_from_bits(   953275311)  // f32.str(): 0.0001000533
assert math.f32_from_bits(   953275314) == math.f32_from_bits(   953275312)  // f32.str(): 0.0001000533
assert math.f32_from_bits(   953275315) == math.f32_from_bits(   953275313)  // f32.str(): 0.0001000533
assert math.f32_from_bits(   953275316) == math.f32_from_bits(   953275314)  // f32.str(): 0.0001000533
assert math.f32_from_bits(   953275317) == math.f32_from_bits(   953275315)  // f32.str(): 0.0001000533
assert math.f32_from_bits(   953275318) == math.f32_from_bits(   953275316)  // f32.str(): 0.0001000533
assert math.f32_from_bits(   953275319) == math.f32_from_bits(   953275317)  // f32.str(): 0.0001000533
assert math.f32_from_bits(   953275320) == math.f32_from_bits(   953275318)  // f32.str(): 0.0001000533
assert math.f32_from_bits(   953275321) == math.f32_from_bits(   953275319)  // f32.str(): 0.0001000533
assert math.f32_from_bits(   953275322) == math.f32_from_bits(   953275320)  // f32.str(): 0.0001000533
assert math.f32_from_bits(   953275323) == math.f32_from_bits(   953275321)  // f32.str(): 0.0001000533
assert math.f32_from_bits(   953275326) == math.f32_from_bits(   953275324)  // f32.str(): 0.0001000534
assert math.f32_from_bits(   953275327) == math.f32_from_bits(   953275325)  // f32.str(): 0.0001000534
assert math.f32_from_bits(   953275328) == math.f32_from_bits(   953275326)  // f32.str(): 0.0001000534
assert math.f32_from_bits(   953275329) == math.f32_from_bits(   953275327)  // f32.str(): 0.0001000534
assert math.f32_from_bits(   953275330) == math.f32_from_bits(   953275328)  // f32.str(): 0.0001000534
assert math.f32_from_bits(   953275331) == math.f32_from_bits(   953275329)  // f32.str(): 0.0001000534
assert math.f32_from_bits(   953275332) == math.f32_from_bits(   953275330)  // f32.str(): 0.0001000534