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Mon, 05 May 2025 02:04:52 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFVe8c/SXPKpUkmPyijE1jDB1zNxdbJ/AaUB37n6Rffwj3hvKuLJVKKEiaOAleaEtbv4n76JQ== X-Received: by 2002:a05:600c:3acd:b0:43b:c6a7:ac60 with SMTP id 5b1f17b1804b1-441bb88c9f1mr92244075e9.10.1746435891520; Mon, 05 May 2025 02:04:51 -0700 (PDT) From: Paolo Bonzini To: qemu-devel@nongnu.org Cc: manos.pitsidianakis@linaro.org, qemu-rust@nongnu.org Subject: [PATCH 05/11] rust: qemu_api_macros: make pattern matching more readable and efficient Date: Mon, 5 May 2025 11:04:30 +0200 Message-ID: <20250505090438.24992-6-pbonzini@redhat.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250505090438.24992-1-pbonzini@redhat.com> References: <20250505090438.24992-1-pbonzini@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -44 X-Spam_score: -4.5 X-Spam_bar: ---- X-Spam_report: (-4.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.411, 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=-1, RCVD_IN_MSPIKE_WL=-0.01, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1746435948649019000 Content-Type: text/plain; charset="utf-8" "let ... else" is useful when visiting syntax trees; it avoids multiple levels of indentation and places the error close to the pattern. While at it, use "ref" to avoid moving the syntax tree objects. Signed-off-by: Paolo Bonzini Reviewed-by: Zhao Liu --- rust/qemu-api-macros/src/lib.rs | 84 +++++++++++++++------------------ 1 file changed, 37 insertions(+), 47 deletions(-) diff --git a/rust/qemu-api-macros/src/lib.rs b/rust/qemu-api-macros/src/lib= .rs index eda0d46d122..0bffd2691b4 100644 --- a/rust/qemu-api-macros/src/lib.rs +++ b/rust/qemu-api-macros/src/lib.rs @@ -16,50 +16,41 @@ fn get_fields<'a>( input: &'a DeriveInput, msg: &str, ) -> Result<&'a Punctuated, MacroError> { - if let Data::Struct(s) =3D &input.data { - if let Fields::Named(fs) =3D &s.fields { - Ok(&fs.named) - } else { - Err(MacroError::Message( - format!("Named fields required for {}", msg), - input.ident.span(), - )) - } - } else { - Err(MacroError::Message( + let Data::Struct(ref s) =3D &input.data else { + return Err(MacroError::Message( format!("Struct required for {}", msg), input.ident.span(), - )) - } + )); + }; + let Fields::Named(ref fs) =3D &s.fields else { + return Err(MacroError::Message( + format!("Named fields required for {}", msg), + input.ident.span(), + )); + }; + Ok(&fs.named) } =20 fn get_unnamed_field<'a>(input: &'a DeriveInput, msg: &str) -> Result<&'a = Field, MacroError> { - if let Data::Struct(s) =3D &input.data { - let unnamed =3D match &s.fields { - Fields::Unnamed(FieldsUnnamed { - unnamed: ref fields, - .. - }) =3D> fields, - _ =3D> { - return Err(MacroError::Message( - format!("Tuple struct required for {}", msg), - s.fields.span(), - )) - } - }; - if unnamed.len() !=3D 1 { - return Err(MacroError::Message( - format!("A single field is required for {}", msg), - s.fields.span(), - )); - } - Ok(&unnamed[0]) - } else { - Err(MacroError::Message( + let Data::Struct(ref s) =3D &input.data else { + return Err(MacroError::Message( format!("Struct required for {}", msg), input.ident.span(), - )) + )); + }; + let Fields::Unnamed(FieldsUnnamed { ref unnamed, .. }) =3D &s.fields e= lse { + return Err(MacroError::Message( + format!("Tuple struct required for {}", msg), + s.fields.span(), + )); + }; + if unnamed.len() !=3D 1 { + return Err(MacroError::Message( + format!("A single field is required for {}", msg), + s.fields.span(), + )); } + Ok(&unnamed[0]) } =20 fn is_c_repr(input: &DeriveInput, msg: &str) -> Result<(), MacroError> { @@ -210,20 +201,19 @@ fn get_repr_uN(input: &DeriveInput, msg: &str) -> Res= ult { } =20 fn get_variants(input: &DeriveInput) -> Result<&Punctuated= , MacroError> { - if let Data::Enum(e) =3D &input.data { - if let Some(v) =3D e.variants.iter().find(|v| v.fields !=3D Fields= ::Unit) { - return Err(MacroError::Message( - "Cannot derive TryInto for enum with non-unit variants.".t= o_string(), - v.fields.span(), - )); - } - Ok(&e.variants) - } else { - Err(MacroError::Message( + let Data::Enum(ref e) =3D &input.data else { + return Err(MacroError::Message( "Cannot derive TryInto for union or struct.".to_string(), input.ident.span(), - )) + )); + }; + if let Some(v) =3D e.variants.iter().find(|v| v.fields !=3D Fields::Un= it) { + return Err(MacroError::Message( + "Cannot derive TryInto for enum with non-unit variants.".to_st= ring(), + v.fields.span(), + )); } + Ok(&e.variants) } =20 #[rustfmt::skip::macros(quote)] --=20 2.49.0