strconv: produce a maximum of 8 digits after the . for f32.str() (fix #25141)

vlib/strconv/f32_f64_to_string_test.v

@@ -172,3 +172,23 @@ fn test_float_to_str() {
 	// assert ftoa.f64_to_str(0.3456789123456, 4)=="3.4568e-01"
 	// assert ftoa.f32_to_str(0.345678, 3)=="3.457e-01"
 }
+
+fn test_issue_25141_1() {
+	assert strconv.ftoa_long_32(0.1234567901) == '0.12345679'
+}
+
+fn test_issue_25141_2() {
+	assert strconv.f32_to_str_l(math.f32_from_bits(1055100472)) == '0.44444442'
+}
+
+fn test_issue_25141_3() {
+	assert strconv.f32_to_str_l(math.f32_from_bits(1055100473)) == '0.44444445'
+}
+
+fn test_issue_25141_4() {
+	assert strconv.f32_to_str_l(math.f32_from_bits(1055100474)) == '0.44444448'
+}
+
+fn test_issue_25141_5() {
+	assert strconv.f32_to_str_l(math.f32_from_bits(1055100475)) == '0.4444445'
+}

vlib/strconv/ftoa.c.v

@@ -19,7 +19,6 @@ https://github.com/cespare/ryu/tree/ba56a33f39e3bbbfa409095d0f9ae168a595feea
 */
 
 // ftoa_64 returns a string in scientific notation with max 17 digits after the dot.
-//
 // Example: assert strconv.ftoa_64(123.1234567891011121) == '1.2312345678910111e+02'
 @[inline]
 pub fn ftoa_64(f f64) string {
@@ -27,7 +26,6 @@ pub fn ftoa_64(f f64) string {
 }
 
 // ftoa_long_64 returns `f` as a `string` in decimal notation with a maximum of 17 digits after the dot.
-//
 // Example: assert strconv.f64_to_str_l(123.1234567891011121) == '123.12345678910111'
 @[inline]
 pub fn ftoa_long_64(f f64) string {
@@ -35,16 +33,14 @@ pub fn ftoa_long_64(f f64) string {
 }
 
 // ftoa_32 returns a `string` in scientific notation with max 8 digits after the dot.
-//
 // Example: assert strconv.ftoa_32(34.1234567) == '3.4123455e+01'
 @[inline]
 pub fn ftoa_32(f f32) string {
 	return f32_to_str(f, 8)
 }
 
-// ftoa_long_32 returns `f` as a `string` in decimal notation with a maximum of 6 digits after the dot.
+// ftoa_long_32 returns `f` as a `string` in decimal notation with a maximum of 8 digits after the dot.
-//
+// Example: assert strconv.ftoa_long_32(0.1234567901) == '0.12345679'
-// Example: assert strconv.ftoa_long_32(34.1234567) == '34.12346'
 @[inline]
 pub fn ftoa_long_32(f f32) string {
 	return f32_to_str_l(f)

vlib/strconv/utilities.c.v

@@ -23,24 +23,24 @@ f64 to string with string format
 */
 
 // TODO: Investigate precision issues
-// f32_to_str_l returns `f` as a `string` in decimal notation with a maximum of 6 digits after the dot.
+// f32_to_str_l returns `f` as a `string` in decimal notation with a maximum of 8 digits after the dot.
-//
+// Example: assert strconv.f32_to_str_l(0.1234567891) == '0.12345679'
-// Example: assert strconv.f32_to_str_l(34.1234567) == '34.12346'
+// Example: assert strconv.f32_to_str_l(34.1234567891) == '34.123455'
 @[manualfree]
 pub fn f32_to_str_l(f f32) string {
-	s := f32_to_str(f, 6)
+	s := f32_to_str(f, 8)
 	res := fxx_to_str_l_parse(s)
 	unsafe { s.free() }
 	return res
 }
 
-// f32_to_str_l_with_dot returns `f` as a `string` in decimal notation with a maximum of 6 digits after the dot.
+// f32_to_str_l_with_dot returns `f` as a `string` in decimal notation with a maximum of 8 digits after the dot.
 // If the decimal digits after the dot are zero, a '.0' is appended for clarity.
 //
 // Example: assert strconv.f32_to_str_l_with_dot(34.) == '34.0'
 @[manualfree]
 pub fn f32_to_str_l_with_dot(f f32) string {
-	s := f32_to_str(f, 6)
+	s := f32_to_str(f, 8)
 	res := fxx_to_str_l_parse_with_dot(s)
 	unsafe { s.free() }
 	return res