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Tue, 12 Aug 2025 03:18:15 -0700 (PDT) Message-ID: <17cfd168-e54f-4cba-b2c2-5118bfbb8ca9@suse.com> Date: Tue, 12 Aug 2025 12:18:13 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] misra: add ASSERT_UNREACHABLE() in default clauses To: Nicola Vetrini Cc: xen-devel@lists.xenproject.org, Stefano Stabellini , Julien Grall , Bertrand Marquis , Michal Orzel , Volodymyr Babchuk , Andrew Cooper , Anthony PERARD , =?UTF-8?Q?Roger_Pau_Monn=C3=A9?= , Dmytro Prokopchuk1 References: <7cd71ed21383c189fedb3250ddde54a593f7f98b.1754944131.git.dmytro_prokopchuk1@epam.com> <8ce96224f88513e4041d33248456fab3@bugseng.com> Content-Language: en-US From: Jan Beulich Autocrypt: addr=jbeulich@suse.com; keydata= xsDiBFk3nEQRBADAEaSw6zC/EJkiwGPXbWtPxl2xCdSoeepS07jW8UgcHNurfHvUzogEq5xk hu507c3BarVjyWCJOylMNR98Yd8VqD9UfmX0Hb8/BrA+Hl6/DB/eqGptrf4BSRwcZQM32aZK 7Pj2XbGWIUrZrd70x1eAP9QE3P79Y2oLrsCgbZJfEwCgvz9JjGmQqQkRiTVzlZVCJYcyGGsD /0tbFCzD2h20ahe8rC1gbb3K3qk+LpBtvjBu1RY9drYk0NymiGbJWZgab6t1jM7sk2vuf0Py O9Hf9XBmK0uE9IgMaiCpc32XV9oASz6UJebwkX+zF2jG5I1BfnO9g7KlotcA/v5ClMjgo6Gl MDY4HxoSRu3i1cqqSDtVlt+AOVBJBACrZcnHAUSuCXBPy0jOlBhxPqRWv6ND4c9PH1xjQ3NP nxJuMBS8rnNg22uyfAgmBKNLpLgAGVRMZGaGoJObGf72s6TeIqKJo/LtggAS9qAUiuKVnygo 3wjfkS9A3DRO+SpU7JqWdsveeIQyeyEJ/8PTowmSQLakF+3fote9ybzd880fSmFuIEJldWxp Y2ggPGpiZXVsaWNoQHN1c2UuY29tPsJgBBMRAgAgBQJZN5xEAhsDBgsJCAcDAgQVAggDBBYC AwECHgECF4AACgkQoDSui/t3IH4J+wCfQ5jHdEjCRHj23O/5ttg9r9OIruwAn3103WUITZee e7Sbg12UgcQ5lv7SzsFNBFk3nEQQCACCuTjCjFOUdi5Nm244F+78kLghRcin/awv+IrTcIWF hUpSs1Y91iQQ7KItirz5uwCPlwejSJDQJLIS+QtJHaXDXeV6NI0Uef1hP20+y8qydDiVkv6l IreXjTb7DvksRgJNvCkWtYnlS3mYvQ9NzS9PhyALWbXnH6sIJd2O9lKS1Mrfq+y0IXCP10eS FFGg+Av3IQeFatkJAyju0PPthyTqxSI4lZYuJVPknzgaeuJv/2NccrPvmeDg6Coe7ZIeQ8Yj t0ARxu2xytAkkLCel1Lz1WLmwLstV30g80nkgZf/wr+/BXJW/oIvRlonUkxv+IbBM3dX2OV8 AmRv1ySWPTP7AAMFB/9PQK/VtlNUJvg8GXj9ootzrteGfVZVVT4XBJkfwBcpC/XcPzldjv+3 HYudvpdNK3lLujXeA5fLOH+Z/G9WBc5pFVSMocI71I8bT8lIAzreg0WvkWg5V2WZsUMlnDL9 mpwIGFhlbM3gfDMs7MPMu8YQRFVdUvtSpaAs8OFfGQ0ia3LGZcjA6Ik2+xcqscEJzNH+qh8V m5jjp28yZgaqTaRbg3M/+MTbMpicpZuqF4rnB0AQD12/3BNWDR6bmh+EkYSMcEIpQmBM51qM EKYTQGybRCjpnKHGOxG0rfFY1085mBDZCH5Kx0cl0HVJuQKC+dV2ZY5AqjcKwAxpE75MLFkr wkkEGBECAAkFAlk3nEQCGwwACgkQoDSui/t3IH7nnwCfcJWUDUFKdCsBH/E5d+0ZnMQi+G0A nAuWpQkjM1ASeQwSHEeAWPgskBQL In-Reply-To: <8ce96224f88513e4041d33248456fab3@bugseng.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 12.08.2025 11:55, Nicola Vetrini wrote: > On 2025-08-12 09:25, Jan Beulich wrote: >> On 11.08.2025 23:25, Nicola Vetrini wrote: >>> On 2025-08-11 22:30, Dmytro Prokopchuk1 wrote: >>>> --- a/xen/arch/arm/decode.c >>>> +++ b/xen/arch/arm/decode.c >>>> @@ -178,6 +178,9 @@ static int decode_thumb(register_t pc, struct >>>> hsr_dabt *dabt) >>>> case 3: /* Signed byte */ >>>> update_dabt(dabt, reg, 0, true); >>>> break; >>>> + default: >>>> + ASSERT_UNREACHABLE(); >>>> + break; >>>> } >>>> >>> >>> I think this is fine, and there should be no problems with the break >>> being unreachable in some configs due to the call property for >>> ASSERT_UNREACHABLE >>> >>> -doc_begin="Calls to function `__builtin_unreachable()' in the >>> expansion >>> of macro >>> `ASSERT_UNREACHABLE()' are not considered to have the `noreturn' >>> property." >>> -call_properties+={"name(__builtin_unreachable)&&stmt(begin(any_exp(macro(name(ASSERT_UNREACHABLE)))))", >>> {"noreturn(false)"}} >>> -doc_end >> >> Did you also see Julien's reply? Imo, to address a complaint from one >> rule, another rule is then being violated: The "default" label itself >> is unreachable here. > > Unfortunately only after sending my reply, however the point here is > that ASSERT_UNREACHABLE() is now considered as if it was not actually a > source of unreachability for any statement below (which is the case only > in configurations where NDEBUG is undefined iirc). This was done mainly > to allow stubs for Rule 2.1 so that their return statement just after an > ASSERT_UNREACHABLE() is not seen as a problem, but given that the > configuration to obtain that is global it influences treatment for other > rules as well, and its addition is relatively recent compared to the > text written in rules.rst. I understand the special treatment of ASSERT_UNREACHABLE(). Yet even if that wasn't there, both the default: label and the break; statement would be unreachable here. Jan