Preprocessors are not put on their own line during code formatting

[SteveDunn]

Hi - there's been a change in Roslyn between Visual Studio 17.13.0 Preview 1 and Preview 2.1.

Previously (rightly or wrongly), I could emit code such as:

    public static global::System.Boolean TryParse( #if NETCOREAPP3_0_OR_GREATER
[global::System.Diagnostics.CodeAnalysis.NotNullWhen(true)] 
#endif
    global::System.String? s, global::System.IFormatProvider? provider, #if NETCOREAPP3_0_OR_GREATER
 [global::System.Diagnostics.CodeAnalysis.MaybeNullWhen(false)] 
#endif
    out AssemblyName result)

Note the preprocessor are on the same line.

Prior to 17.13.0 Preview 2.1 (I tried with 17.13.0 Preview 1), the formatter would place those preprocessors on different lines, e.g.:

    public static global::System.Boolean TryParse( #if NETCOREAPP3_0_OR_GREATER
[global::System.Diagnostics.CodeAnalysis.NotNullWhen(true)] 
#endif
    global::System.String? s, global::System.IFormatProvider? provider, #if NETCOREAPP3_0_OR_GREATER
 [global::System.Diagnostics.CodeAnalysis.MaybeNullWhen(false)] 
#endif

The formatting code that I use is:

    public static SourceText FormatSource(string source)
    {
        SyntaxTree syntaxTree = CSharpSyntaxTree.ParseText(source);
        SyntaxNode root = syntaxTree.GetRoot();
        SyntaxNode formatted = root.NormalizeWhitespace();

        return SourceText.From(formatted.ToFullString(), Encoding.UTF8);
    }

This was reported in my source generor, Vogen: SteveDunn/Vogen#725

The issue is obviously that preprocessors need to be on their own lines, but I thought I'd let you know as I would guess there are other source generators that miss this.

[CyrusNajmabadi]

Yes. We made a change at the parsing level to not even consider these to be pp directives since they aren't as far as the language is concerned.

That this worked before was not intentional. And an SG should not emit code in this fashion.