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Thu, 20 Mar 2025 04:33:58 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGhEOXVJklW7b0P8YsQfg/Yd8oxtXANrjsZINkKIpBb7Mw8o5asXUqiOmuO5AYjy8rTqqvd9Q== X-Received: by 2002:a5d:6c67:0:b0:391:2e0f:efec with SMTP id ffacd0b85a97d-399739b45f4mr4290472f8f.7.1742470437759; Thu, 20 Mar 2025 04:33:57 -0700 (PDT) Received: from [192.168.10.48] ([151.49.194.153]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-39972df9b9esm5010041f8f.18.2025.03.20.04.33.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Mar 2025 04:33:57 -0700 (PDT) From: Paolo Bonzini To: qemu-devel@nongnu.org Cc: Peter Maydell Subject: [PATCH] rust: assertions: add const_assert Date: Thu, 20 Mar 2025 12:33:56 +0100 Message-ID: <20250320113356.799412-1-pbonzini@redhat.com> X-Mailer: git-send-email 2.48.1 MIME-Version: 1.0 Received-SPF: pass client-ip=170.10.129.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -23 X-Spam_score: -2.4 X-Spam_bar: -- X-Spam_report: (-2.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.332, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Add a new assertion that is similar to "const { assert!(...) }" but can be used outside functions and with older versions of Rust. Similar in concept (but not in code) to the homonymous macro of the "static_assertions" crate. Suggested-by: Peter Maydell Signed-off-by: Paolo Bonzini --- rust/qemu-api/src/assertions.rs | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/rust/qemu-api/src/assertions.rs b/rust/qemu-api/src/assertions.rs index 104dec39774..1fa3955d867 100644 --- a/rust/qemu-api/src/assertions.rs +++ b/rust/qemu-api/src/assertions.rs @@ -120,3 +120,25 @@ macro_rules! assert_match { ); }; } + +/// Assert at compile time that an expression is true. This is similar +/// to `const { assert!(...); }` but it works outside functions, as well as +/// on versions of Rust before 1.79. +/// +/// # Examples +/// +/// ``` +/// # use qemu_api::const_assert; +/// const_assert!("abc".len() == 3); +/// ``` +/// +/// ```compile_fail +/// # use qemu_api::const_assert; +/// const_assert!("abc".len() == 2); // does not compile +/// ``` +#[macro_export] +macro_rules! const_assert { + ($x:expr) => { + const _: [(); { const VALUE__: bool = $x; VALUE__ as usize }] = [()]; + }; +}