Mailing List Archive

commit 4dc9a8b0606770dc9c6be20ff5a74a9af5fcba70
Author: Nicola Vetrini <nicola.vetrini@bugseng.com>
AuthorDate: Thu Feb 15 14:06:17 2024 +0100
Commit: Stefano Stabellini <stefano.stabellini@amd.com>
CommitDate: Wed Mar 13 17:21:51 2024 -0700

automation/eclair_analysis: deviate certain macros for Rule 20.12

Certain macros are allowed to violate the Rule, since their meaning and
intended use is well-known to all Xen developers.

Variadic macros that rely on the GCC extension for removing a trailing
comma when token pasting the variable argument are similarly
well-understood and therefore allowed.

No functional change.

Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
---
automation/eclair_analysis/ECLAIR/deviations.ecl | 20 ++++++++++++++++++++
docs/misra/deviations.rst | 22 ++++++++++++++++++++++
2 files changed, 42 insertions(+)

diff --git a/automation/eclair_analysis/ECLAIR/deviations.ecl b/automation/eclair_analysis/ECLAIR/deviations.ecl
index 9ac3ee4dfd..53f7623454 100644
--- a/automation/eclair_analysis/ECLAIR/deviations.ecl
+++ b/automation/eclair_analysis/ECLAIR/deviations.ecl
@@ -405,6 +405,26 @@ in assignments."
{safe, "left_right(^[(,\\[]$,^[),\\]]$)"}
-doc_end

+-doc_begin="Uses of variadic macros that have one of their arguments defined as
+a macro and used within the body for both ordinary parameter expansion and as an
+operand to the # or ## operators have a behavior that is well-understood and
+deliberate."
+-config=MC3R1.R20.12,macros+={deliberate, "variadic()"}
+-doc_end
+
+-doc_begin="Uses of a macro parameter for ordinary expansion and as an operand
+to the # or ## operators within the following macros are deliberate, to provide
+useful diagnostic messages to the user."
+-config=MC3R1.R20.12,macros+={deliberate, "name(ASSERT||BUILD_BUG_ON||BUILD_BUG_ON_ZERO)"}
+-doc_end
+
+-doc_begin="The helper macro GENERATE_CASE may use a macro parameter for ordinary
+expansion and token pasting to improve readability. Only instances where this
+leads to a violation of the Rule are deviated."
+-file_tag+={deliberate_generate_case, "^xen/arch/arm/vcpreg\\.c$"}
+-config=MC3R1.R20.12,macros+={deliberate, "name(GENERATE_CASE)&&loc(file(deliberate_generate_case))"}
+-doc_end
+
#
# General
#
diff --git a/docs/misra/deviations.rst b/docs/misra/deviations.rst
index ce855ddae6..6d532a872d 100644
--- a/docs/misra/deviations.rst
+++ b/docs/misra/deviations.rst
@@ -336,6 +336,28 @@ Deviations related to MISRA C:2012 Rules:
(4) as lhs in assignments.
- Tagged as `safe` for ECLAIR.

+ * - R20.12
+ - Variadic macros that use token pasting often employ the gcc extension
+ `ext_paste_comma`, as detailed in `C-language-toolchain.rst`, which is
+ not easily replaceable; macros that in addition perform regular argument
+ expansion on the same argument subject to the # or ## operators violate
+ the Rule if the argument is a macro.
+ - Tagged as `deliberate` for ECLAIR.
+
+ * - R20.12
+ - Macros that are used for runtime or build-time assertions contain
+ deliberate uses of an argument as both a regular argument and a
+ stringification token, to provide useful diagnostic messages.
+ - Tagged as `deliberate` for ECLAIR.
+
+ * - R20.12
+ - GENERATE_CASE is a local helper macro that allows some selected switch
+ statements to be more compact and readable. As such, the risk of
+ developer confusion in using such macro is deemed negligible. This
+ construct is deviated only in Translation Units that present a violation
+ of the Rule due to uses of this macro.
+ - Tagged as `deliberate` for ECLAIR.
+
Other deviations:
-----------------

--
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