Bug 23770 - Volatile Pointers rejected by compiler
Summary: Volatile Pointers rejected by compiler
Status: RESOLVED FIXED
Alias: None
Product: Compilers
Classification: Mono
Component: C# ()
Version: unspecified
Hardware: Macintosh Mac OS
: --- normal
Target Milestone: ---
Assignee: Marek Safar
URL:
Depends on:
Blocks:
 
Reported: 2014-10-12 17:56 UTC by Paul
Modified: 2014-11-10 06:07 UTC (History)
1 user (show)

Tags:
Is this bug a regression?: ---
Last known good build:

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Status:
RESOLVED FIXED

Description Paul 2014-10-12 17:56:34 UTC
Per Microsoft's documentation, (and compiles successfully in MSVC2010) a pointer in unsafe context is a valid volatile type.
http://msdn.microsoft.com/en-us/library/x13ttww7.aspx

But Mono's compiler rejects this with Error CS0677: "A volatile field cannot be of the type 'byte*'"; "A volatile field cannot be of the type 'int*'"

Example declaration (inside an unsafe project):
	volatile byte* begin;
	volatile int* head, tail;

This appears to originate in the CanBeVolatile() method in field.cs:
https://github.com/mono/mono/blob/master/mcs/mcs/field.cs

I'm hoping this is a small fix and that you just need to add an additional check for a pointer here?

Currently running the following version of MonoDevelop:
Xamarin Studio
Version 5.5 (build 227)
Installation UUID: 51e6b202-7a9b-4e3a-af9e-7c2cffb47d60
Runtime:
	Mono 3.10.0 ((detached/47db868)
	GTK+ 2.24.23 (Raleigh theme)

	Package version: 310000019

Although based on my link above this problem seems to exist in master right now. Thanks in advance!
Comment 1 Paul 2014-10-12 19:39:57 UTC
Is it possible that this somehow broke in Mono 3.10?
I downgraded to MRE 3.08 and now the code is building again.
Comment 2 Marek Safar 2014-11-10 06:07:55 UTC
Fixed in master and Mono 3.12