test and fix float.str() precision

Author: serkonda7

lib/builtin/number.c.bt

@@ -54,15 +54,15 @@ pub fun (n u64) str() string {
 }
 
 pub fun (n f32) str() string {
-	length := #C.snprintf(#C.'NULL' as &u8, 0, "%g".str, n as f64)
+	length := #C.snprintf(#C.'NULL' as &u8, 0, "%.9g".str, n as f64)
 	buf := #C.malloc(length + 1)
-	_ = #C.snprintf(buf, length + 1, "%g".str, n as f64)
+	_ = #C.snprintf(buf, length + 1, "%.9g".str, n as f64)
 	return from_c_string(buf)
 }
 
 pub fun (n f64) str() string {
-	length := #C.snprintf(#C.'NULL' as &u8, 0, "%g".str, n)
+	length := #C.snprintf(#C.'NULL' as &u8, 0, "%.17g".str, n)
 	buf := #C.malloc(length + 1)
-	_ = #C.snprintf(buf, length + 1, "%g".str, n)
+	_ = #C.snprintf(buf, length + 1, "%.17g".str, n)
 	return from_c_string(buf)
 }

tests/auto_str/auto_str_test.bt

@@ -5,3 +5,16 @@ fun test_array() {
 	a := [true, false, true]
 	assert a.str() == "[true, false, true]"
 }
+
+struct Bar {
+	f f64
+}
+
+fun test_struct() {
+	b := Bar {
+		f = 3.14
+	}
+	assert b.str() == 'Bar{
+  f = 3.14
+}'
+}

tests/auto_str/auto_str_test.js.bt

@@ -10,7 +10,6 @@ fun test_map() {
 	assert m.str() == "{'foo': 62, 'bar': 31}"
 }
 
-// TODO C floats
 struct Bar {
 	f f64
 }
@@ -19,15 +18,7 @@ struct Foo {
 	b Bar
 }
 
-fun test_struct() {
-	b := Bar {
-		f = 3.14
-	}
-	assert b.str() == 'Bar{
-  f = 3.14
-}'
-}
-
+// TODO C fix nested structs
 fun test_nested_struct() {
 	f := Foo {}
 	assert f.str() == 'Foo{

tests/auto_str/float_precision_test.bt

@@ -0,0 +1,7 @@
+// SPDX-FileCopyrightText: Lukas Neubert
+// SPDX-License-Identifier: MIT
+
+fun test_float_str_precision() {
+	f := 123.45678901234567890
+	assert f.str() == '123.45678901234568'
+}