toml: make value of `+nan`/`-nan` decode to `nan` (#12542)

vlib/toml/ast/types.v

@@ -157,8 +157,9 @@ pub fn (b Bool) str() string {
 // Number can be integers, floats, infinite, NaN - they can have exponents (`5e2`) and be sign prefixed (`+2`).
 pub struct Number {
 pub:
+	pos token.Position
+pub mut:
 	text string
-	pos  token.Position
 }
 
 // str returns the `string` representation of the `Number` type.

vlib/toml/decoder/decoder.v

@@ -30,6 +30,10 @@ fn (d Decoder) modify(mut value ast.Value) ? {
 			mut v := &(value as ast.Quoted)
 			d.decode_quoted(mut v) ?
 		}
+		ast.Number {
+			mut v := &(value as ast.Number)
+			d.decode_number(mut v) ?
+		}
 		else {}
 	}
 }
@@ -44,6 +48,13 @@ fn (d Decoder) decode_quoted(mut q ast.Quoted) ? {
 	decode_quoted_escapes(mut q) ?
 }
 
+// decode_number decodes the `n ast.Number` into valid TOML.
+fn (d Decoder) decode_number(mut n ast.Number) ? {
+	if n.text == '-nan' || n.text == '+nan' {
+		n.text = 'nan'
+	}
+}
+
 // decode_quoted_escapes returns an error for any disallowed escape sequences.
 // Delimiters in TOML has significant meaning:
 // '/''' delimits *literal* strings (WYSIWYG / What-you-see-is-what-you-get)

vlib/toml/tests/burntsushi.toml-test_test.v

@@ -17,8 +17,6 @@ const (
 	valid_value_exceptions = [
 		// Integer
 		'integer/long.toml', // TODO awaits BUG fix with strconv.parse_int('-9223372036854775808')
-		// Float
-		'float/inf-and-nan.toml',
 		// Table
 		'table/array-implicit.toml',
 		// Date-time