Re: [edk2-devel] [PATCH] edk II C Coding Standard: Remove section 5.4.2.2 STATIC

["Chang, Abner" <abner.chang@amd.com>]

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[AMD Official Use Only - General]

HI Ard, attach the patch review for the 'static'.  Please check it and provide your feedback on it if you think the phrase is not strong enough.

Thanks
Abner

> -----Original Message-----
> From: Kinney, Michael D <michael.d.kinney@intel.com>
> Sent: Monday, November 28, 2022 11:41 PM
> To: Ard Biesheuvel <ardb@kernel.org>; devel@edk2.groups.io; Kinney,
> Michael D <michael.d.kinney@intel.com>
> Cc: Chang, Abner <Abner.Chang@amd.com>; Ni, Ray <ray.ni@intel.com>;
> Gao, Liming <gaoliming@byosoft.com.cn>
> Subject: RE: [edk2-devel] [PATCH] edk II C Coding Standard: Remove section
> 5.4.2.2 STATIC
> 
> Caution: This message originated from an External Source. Use proper
> caution when opening attachments, clicking links, or responding.
> 
> 
> Ard,
> 
> I agree it should be a strong recommendation for all of these reasons.
> 
> There is a patch review for this spec for use of 'static'.  Can you please
> provide feedback with your recommended content?
> 
> Thanks,
> 
> Mike
> 
> > -----Original Message-----
> > From: Ard Biesheuvel <ardb@kernel.org>
> > Sent: Monday, November 28, 2022 1:08 AM
> > To: devel@edk2.groups.io; Kinney, Michael D
> > <michael.d.kinney@intel.com>
> > Cc: Chang, Abner <Abner.Chang@amd.com>; Ni, Ray <ray.ni@intel.com>;
> > Gao, Liming <gaoliming@byosoft.com.cn>
> > Subject: Re: [edk2-devel] [PATCH] edk II C Coding Standard: Remove
> > section 5.4.2.2 STATIC
> >
> > On Tue, 22 Nov 2022 at 19:10, Michael D Kinney
> > <michael.d.kinney@intel.com> wrote:
> > >
> > > Hi Abner,
> > >
> > > Removing that section 5.4.2.2 is required to close this bug.
> > >
> > > Meaning of 'static' is covered by the ANSI C standards.
> > >
> > > Use of 'static' for non-public variable/functions in EDK II
> > > libraries/modules is recommended.
> > >
> > > However, it is not required.  It is recommended to reduce chances of
> > > symbol conflicts at link time.  Current approach is if a link
> > > failure occurs for multiply defined symbols and those are non-public
> > > symbols, the 'static' attribute can be applied to the non-public
> > > symbols in the components that generated the link failure.
> > >
> > > It may be good to mention this recommendation in the CSS.
> > >
> > > I will let you decide when this recommendation needs to be added to
> > > CSS.
> > >
> >
> > 'static' is not just a tool to avoid symbol conflicts. It also avoids
> > abuse of symbols that are assumed to have a private nature but can be
> > linked to nonetheless (e.g., in static libraries). Ideally, any
> > library should only export the symbols that it defines as part of its
> > interface, although this is not currently feasible of a library
> > consists of multiple object files.
> >
> > Another thing to keep in mind is that static is used by the compiler
> > to make inferences about the value. A static global variable can only
> > be modified by the code in the same compilation unit, and so the
> > compiler is free to optimize accesses or perform constant propagation
> > and drop it entirely if it only observes reads and no writes from the
> > variable.
> >
> > I consider it good developer hygiene to always use static on global
> > symbols (code and data) unless the symbol needs to be shared with
> > other compilation units.

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From: "Chang, Abner via groups.io" <abner.chang=amd.com@groups.io>
To: "devel@edk2.groups.io" <devel@edk2.groups.io>
Cc: Ray Ni <ray.ni@intel.com>, Michael D Kinney <michael.d.kinney@intel.com>
Subject: [edk2-devel] [PATCH V2] edk II C Coding Standard: Remove section 5.4.2.2 STATIC
Date: Sat, 26 Nov 2022 09:02:57 +0000
Message-ID: <172B1708C307B48B.11309@groups.io>

Caution: This message originated from an External Source. Use proper caution when opening attachments, clicking links, or responding.


From: Abner Chang <abner.chang@amd.com>

BZ #1766

Revise the sections that mention the usage of "static" and
remove section 5.4.2.2.1 and 5.4.2.2.2 section.
We are not allowed to use upper-case STATIC in the source
file now.
Just follow C standard and use the lower-case 'static'.

Leave the macro "#deifne STATIC static" there without
removing it to keep the backward compatible.

Signed-off-by: Abner Chang <abner.chang@amd.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
---
 5_source_files/54_code_file_structure.md    | 19 ++++---------------
 5_source_files/56_declarations_and_types.md |  2 +-
 2 files changed, 5 insertions(+), 16 deletions(-)

diff --git a/5_source_files/54_code_file_structure.md b/5_source_files/54_code_file_structure.md
index 0c4d6a2..6a9fcc7 100644
--- a/5_source_files/54_code_file_structure.md
+++ b/5_source_files/54_code_file_structure.md
@@ -267,19 +267,8 @@ specified in Section 5.4.1.3 "Compile-Time Names".
 Thus, while it might be legal C, do **not** declare external variables anywhere
 other than at the top level of a file as specified by this document.

-#### 5.4.2.2 Static
+#### 5.4.2.2 static

-An object declared `STATIC` has either file or block scope.
-
-##### 5.4.2.2.1 Do not reuse an object or function identifier with static storage duration.
-
-Throughout the set of source files defined within a single .inf file, do not
-reuse an identifier with static storage duration. The compiler may not be
-confused by this, but the user may confuse unrelated variables with the same
-name.
-
-##### 5.4.2.2.2 Functions should not be declared STATIC.
-
-Some source-level debuggers are unable to resolve static functions. Until it
-can be verified that no one is dependent upon a debugger with this limitation,
-it is strongly recommended that functions not be declared static.
+Use static for the variables and functions those are non-public to other source
+files is encouraged. This reduces the chances of symbol redefined error during
+link process.
\ No newline at end of file
diff --git a/5_source_files/56_declarations_and_types.md b/5_source_files/56_declarations_and_types.md
index ec1803d..db98b95 100644
--- a/5_source_files/56_declarations_and_types.md
+++ b/5_source_files/56_declarations_and_types.md
@@ -38,7 +38,7 @@
 Any abstract type that is defined must be constructed from other abstract types
 or from common EFI data types.

-#### 5.6.1.2 The use of int, unsigned, char, void, static, long is a violation of the coding convention.
+#### 5.6.1.2 The use of int, unsigned, char, void, long and the data types those are defined in EFI Data Types is a violation of the coding convention.

 The corresponding EFI types must be used instead.

--
2.37.1.windows.1



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