On Mon, May 18, 2020 at 13:46:46 +0100, Sami Mujawar wrote:
> The VS2017 compiler reports 'warning C6326: potential
> comparison of a constant with another constant' when
> a fixed PCD value is compared with a constant value.
>
> The faulting code is as marked by '-->' below:
>
> --> if (FixedPcdGet32 (PL011UartInteger) != 0) {
> Integer = FixedPcdGet32 (PL011UartInteger);
> Fractional = FixedPcdGet32 (PL011UartFractional);
> } else {
> ...
>
> The macro FixedPcdGet32 (PL011UartInteger) evaluates
> to a macro _PCD_VALUE_PL011UartInteger that is defined
> by the build system to represent the UART Integer
> value. Therefore, the VS2017 compiler reports the above
> warning.
>
> In this case the warning reported by the Visual Studio
> compiler does not evaluate to an issue. However, it can
> be useful to detect potential issues in other scenarios.
> Other compilers may either be incapable of detecting and
> reporting comparison with constant warnings or may be
> good at reducing false positives. So, it is definitely
> useful to keep this warning enabled, and disabling it
> case by case is a suitable option.
>
> Therefore, disable this warning for Visual studio
> compilers using the pragma suppress directive that:
> 'Pushes the current state of the pragma on the stack,
> disables the specified warning for the next line, and
> then pops the warning stack so that the pragma state
> is reset.'
>
> Signed-off-by: Sami Mujawar <sami.muja...@arm.com>
Reviewed-by: Leif Lindholm <l...@nuviainc.com>
However, this patch set is garbled. The cover-letter claims to be v3,
1/2 claims to be v1-resend and 2/2 claims to be v2.
Please use git format-patch for generating your patches before sending
out - that will do the right thing.
/
Leif
> ---
>
> Notes:
> v2:
> - Update patch to selectively suppress comparison of [SAMI]
> constant warning and submit as a separate series.
>
> v1:
> - Fix comparison of constant warning reported by VS2017 [SAMI]
> - Various feedbacks can be seen at:
> https://edk2.groups.io/g/devel/topic/32999801#46278
>
> ArmPlatformPkg/Library/PL011UartLib/PL011UartLib.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/ArmPlatformPkg/Library/PL011UartLib/PL011UartLib.c
> b/ArmPlatformPkg/Library/PL011UartLib/PL011UartLib.c
> index
> 2d3c279cce49304959953ec4a34b50e09a7d0045..3c915e1e8de22a0b0b4cc46d495a5a6cbc784013
> 100644
> --- a/ArmPlatformPkg/Library/PL011UartLib/PL011UartLib.c
> +++ b/ArmPlatformPkg/Library/PL011UartLib/PL011UartLib.c
> @@ -2,7 +2,7 @@
> Serial I/O Port library functions with no library constructor/destructor
>
> Copyright (c) 2008 - 2010, Apple Inc. All rights reserved.<BR>
> - Copyright (c) 2011 - 2019, ARM Ltd. All rights reserved.<BR>
> + Copyright (c) 2011 - 2020, ARM Ltd. All rights reserved.<BR>
>
> SPDX-License-Identifier: BSD-2-Clause-Patent
>
> @@ -174,6 +174,14 @@ PL011UartInitializePort (
> //
>
> // If PL011 Integer value has been defined then always ignore the BAUD rate
> +#if defined(_MSC_EXTENSIONS)
> + // Suppress 'warning C6326' reported by Visual Studio compiler using
> + // the suppress pragma directive that: 'Pushes the current state of
> + // the pragma on the stack, disables the specified warning for the
> + // next line, and then pops the warning stack so that the pragma state
> + // is reset.'
> +#pragma warning(suppress:6326)
> +#endif
> if (FixedPcdGet32 (PL011UartInteger) != 0) {
> Integer = FixedPcdGet32 (PL011UartInteger);
> Fractional = FixedPcdGet32 (PL011UartFractional);
> --
> 'Guid(CE165669-3EF3-493F-B85D-6190EE5B9759)'
>
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