{"header":{"message":"Support downcasting ContextError to C and E\n","description":null,"timestamp":"2019-10-28T00:52:05Z","authors":[{"email":"dtolnay@gmail.com","name":"David Tolnay"}]},"hash":"W5YRNIBZIMTQLOKIBWBF7CHCIOLKXVHV7Y2AIKMKG7GCQSAVZKBAC","authors":[],"deps":{"hashes":[["W5YRNIBZIMTQLOKIBWBF7CHCIOLKXVHV7Y2AIKMKG7GCQSAVZKBAC","Support downcasting ContextError to C and E\n"],["AA",null],["VWTWVVRECX62JABUZYFCTCPWTXXT3DB4635RIAGCKIQMGJ7VXRGAC","Move downcasting into vtable\n"],["ZA66LGSAXNKRWKA7QLKM5UGSZE3KTGTRL6MNGA426YYW65HYIDPAC","No need for object_raw, object_mut_raw to be unsafe\n"],["LX7EZ6TKJCQI3K7SV56WMTPFY672WN5UOBGXKKXQI7S73GMWNNXAC","Change Error::construct to unsafe fn because TypeId must be correct\n"],["UB53AXKRDBNRMOXEAJISW7G4IZLBBWIDW2GPHNGQVRBMFLVKWUTQC","Swap ContextError type parameters to match type name\n"],["Z4YYQXEE4OQPF22I4LD7RVQIBKK67AHCYR6C35MANUCIC4P3EPYQC","Deallocate with the right Layout during downcast\n"],["T64LKJ2RTUDFYSJQI7KF4WHZYXZHNEGNOS7ZMMCRIQZ4YN5LOOMAC","Fix potential UB by removing reliance on trait object layout\n\nAdds a raw vtable object (similar to `RawWakerVTable`) that is manually\ncreated and has methods to dynamically cast to `dyn StdError`.\n"],["AEVUCD3O343GYQLS7EO5ULPGVTGXSOXDKU3RVENI3ZJ3MFYTZ2ZAC","Rename source to object in vtable\n\nSince these function pointers have nothing to do with Error::source.\n"],["NPOFDGQF4CE72IZBT5Y7KPIBHWPPNOEPBYD5RTUHSVUJ2W4XFRVQC","Deallocate ErrorImpl with the right Layout\n"],["CITEDKPB6MKVZUEYEDE5ZKTNVY35HCOAXKDPYG7YLLEOVFNMSRXQC","Import implementation from fehler 1.0.0-alpha.1\n"],["UPPVYBGC7MQBUCAAB6KW3R5KWHGASFTTXVUHEWRNP27SK3CI7UHQC","Introduce safe from_std and matching from_adhoc\n"],["KCOCFOS6KMCTVS6K3WE6KOQSWC3QNWN2E36ASHQPP3Z3H4BHR3NQC","Support context on Option\n"],["F5MLEQJFOB443KKN22TYYJN2TR52653MD4VXSEYZQBNWWJYES5VQC","Update vtable function names to match the implementation names\n"],["4SNDY6U7TDCVRCARTEQ7JLATJFDMUMEFV2GSLKMQJY7RFNPU5HDQC","Fix UB when accessing errors with large alignment\n"],["VSLQNAQBAGOJC2IV55V3W755UIPN47J4RTCCLCABRFFFUU5LT2JQC","Also move Error and Chain to get usable paths in diagnostics\n"],["ZKAEZKAMMQWPQIV6X2CFQUUOG7RBJOE3MNXLBH4J3ZASUYTCZJAQC","Move ContextError to error.rs in preparation for refactor\n"],["ZDN7BJ3JA3VL4AYWX3SV24GHP6NCAETJVAKAXKMIZTLHTWLUNMOQC","Detect nightly and only expose backtrace if available\n"],["UR5XDZ3SS7QXSUFAYQDYUXX4QDROIYVXUH3Z24F6PAWJDNODAZYAC","Rename InnerException to ErrorImpl\n"],["TOXJRHV7ZUPHWXCA4TAG3YRBTIPUZQ5BNX34D3VD2JAIYLRN6XSAC","Move TypeId out of the Box allocation\n"],["CZP5PD5NYLDULLW43VOL6V75CH6DDEJO7H6JSGQSIV2WNSQF4A6QC","Rename vtable object ref and mut methods that are no longer raw ptr\n"],["BA4YE6QGRTYONATHUP347OFUBUCWXQPNZ6Q5DIQ2DLJLRZJ6AC4AC","Eliminate backtrace_if_absent in Error::context\n\nThis avoids stepping through the list of causes when adding context to\nthe anyhow::Error type which is known to already hold a backtrace.\n\nReduces the release-mode time of the following loop from 4 seconds to 4\nmilliseconds.\n\n let mut err = anyhow!(\"...\");\n for _ in 0..25000 {\n err = err.context(\"...\");\n }\n"],["TI53BDDVHWRE4CCKWD23WO7VR4AMIDZZEXDEKEJY2AUJL2U6PSOQC","Specify types where the manual vtable relies on them\n"],["RFSCYZWH7VQUGHAM374YUDGZGM5S4KT6NXWDMHXL4767SCRSL2DQC","Expand ContextError vtable to prepare for extending downcast support\n"],["RIKD63GT7RFV3UAV4BYD57GFXKXALWUP6J7AAHB3M6JVAZ3WFTXAC","Add conversion from Error to Box\n"]],"deps":["VWTWVVRECX62JABUZYFCTCPWTXXT3DB4635RIAGCKIQMGJ7VXRGAC"],"known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},"hunks":[{"Edit":{"inode":{"change":3,"pos":3238},"path":"src/error.rs","line":32,"atom":{"EdgeMap":{"edges":[{"previous":"BLOCK","flag":"BLOCK | DELETED","from":{"change":3,"pos":79},"to":{"change":3,"start":79,"end":134},"introduced_by":3}],"inode":{"change":3,"pos":3238}}},"contents":[{"Del":" object_drop_front: object_drop_front::,\n"}]}},{"Edit":{"inode":{"change":3,"pos":3238},"path":"src/error.rs","line":37,"atom":{"NewVertex":{"up_context":[{"change":2,"pos":83}],"down_context":[{"change":3,"pos":300}],"flag":"BLOCK","start":0,"end":54,"inode":{"change":3,"pos":3238}}},"contents":[{"Add":" object_drop_rest: object_drop_front::,"}]}},{"Edit":{"inode":{"change":3,"pos":3238},"path":"src/error.rs","line":51,"atom":{"EdgeMap":{"edges":[{"previous":"BLOCK","flag":"BLOCK | DELETED","from":{"change":3,"pos":537},"to":{"change":3,"start":537,"end":606},"introduced_by":3}],"inode":{"change":3,"pos":3238}}},"contents":[{"Del":" object_drop_front: object_drop_front::>,\n"}]}},{"Edit":{"inode":{"change":3,"pos":3238},"path":"src/error.rs","line":56,"atom":{"NewVertex":{"up_context":[{"change":2,"pos":135}],"down_context":[{"change":3,"pos":814}],"flag":"BLOCK","start":55,"end":109,"inode":{"change":3,"pos":3238}}},"contents":[{"Add":" object_drop_rest: object_drop_front::,"}]}},{"Edit":{"inode":{"change":3,"pos":3238},"path":"src/error.rs","line":71,"atom":{"EdgeMap":{"edges":[{"previous":"BLOCK","flag":"BLOCK | DELETED","from":{"change":3,"pos":1118},"to":{"change":3,"start":1118,"end":1187},"introduced_by":3}],"inode":{"change":3,"pos":3238}}},"contents":[{"Del":" object_drop_front: object_drop_front::>,\n"}]}},{"Edit":{"inode":{"change":3,"pos":3238},"path":"src/error.rs","line":76,"atom":{"NewVertex":{"up_context":[{"change":2,"pos":187}],"down_context":[{"change":3,"pos":1395}],"flag":"BLOCK","start":110,"end":164,"inode":{"change":3,"pos":3238}}},"contents":[{"Add":" object_drop_rest: object_drop_front::,"}]}},{"Edit":{"inode":{"change":3,"pos":3238},"path":"src/error.rs","line":93,"atom":{"EdgeMap":{"edges":[{"previous":"BLOCK","flag":"BLOCK | DELETED","from":{"change":3,"pos":383},"to":{"change":3,"start":383,"end":455},"introduced_by":3}],"inode":{"change":3,"pos":3238}}},"contents":[{"Del":" object_drop_front: object_drop_front::>,\n"}]}},{"Replacement":{"inode":{"change":3,"pos":3238},"path":"src/error.rs","line":96,"ins":{"up_context":[{"change":3,"pos":633}],"down_context":[{"change":3,"pos":689}],"flag":"BLOCK","start":165,"end":320,"inode":{"change":3,"pos":3238}},"del":{"edges":[{"previous":"BLOCK","flag":"BLOCK | DELETED","from":{"change":3,"pos":633},"to":{"change":3,"start":633,"end":689},"introduced_by":3},{"previous":"BLOCK","flag":"BLOCK | DELETED","from":{"change":3,"pos":689},"to":{"change":2,"start":188,"end":256},"introduced_by":2}],"inode":{"change":3,"pos":3238}},"ins_contents":[{"Add":" object_is: context_is::,"},{"Add":" object_downcast: context_downcast::,"},{"Add":" object_drop_rest: context_drop_rest::,"}],"del_contents":[{"Del":" object_is: object_is::>,\n"},{"Del":" object_downcast: object_downcast::>,\n"}]}},{"Edit":{"inode":{"change":3,"pos":3238},"path":"src/error.rs","line":193,"atom":{"EdgeMap":{"edges":[{"previous":"BLOCK","flag":"BLOCK | DELETED","from":{"change":3,"pos":148},"to":{"change":3,"start":148,"end":224},"introduced_by":3}],"inode":{"change":3,"pos":3238}}},"contents":[{"Del":" object_drop_front: object_drop_front::>,\n"}]}},{"Edit":{"inode":{"change":3,"pos":3238},"path":"src/error.rs","line":198,"atom":{"NewVertex":{"up_context":[{"change":2,"pos":329}],"down_context":[{"change":3,"pos":474}],"flag":"BLOCK","start":321,"end":396,"inode":{"change":3,"pos":3238}}},"contents":[{"Add":" object_drop_rest: object_drop_front::>,"}]}},{"Replacement":{"inode":{"change":3,"pos":3238},"path":"src/error.rs","line":287,"ins":{"up_context":[{"change":2,"pos":738}],"down_context":[{"change":2,"pos":793}],"flag":"BLOCK","start":397,"end":459,"inode":{"change":3,"pos":3238}},"del":{"edges":[{"previous":"BLOCK","flag":"BLOCK | DELETED","from":{"change":2,"pos":738},"to":{"change":2,"start":738,"end":793},"introduced_by":2}],"inode":{"change":3,"pos":3238}},"ins_contents":[{"Add":" (erased.vtable.object_drop_rest)(erased, target);"}],"del_contents":[{"Del":" (erased.vtable.object_drop_front)(erased);\n"}]}},{"Edit":{"inode":{"change":3,"pos":3238},"path":"src/error.rs","line":403,"atom":{"EdgeMap":{"edges":[{"previous":"BLOCK","flag":"BLOCK | DELETED","from":{"change":3,"pos":519},"to":{"change":3,"start":393,"end":447},"introduced_by":3}],"inode":{"change":3,"pos":3238}}},"contents":[{"Del":" object_drop_front: unsafe fn(Box>),\n"}]}},{"Edit":{"inode":{"change":3,"pos":3238},"path":"src/error.rs","line":408,"atom":{"NewVertex":{"up_context":[{"change":2,"pos":1271}],"down_context":[{"change":3,"pos":520}],"flag":"BLOCK","start":460,"end":521,"inode":{"change":3,"pos":3238}}},"contents":[{"Add":" object_drop_rest: unsafe fn(Box>, TypeId),"}]}},{"Replacement":{"inode":{"change":3,"pos":3238},"path":"src/error.rs","line":418,"ins":{"up_context":[{"change":3,"pos":471}],"down_context":[{"change":3,"pos":527}],"flag":"BLOCK","start":522,"end":594,"inode":{"change":3,"pos":3238}},"del":{"edges":[{"previous":"BLOCK","flag":"BLOCK | DELETED","from":{"change":3,"pos":471},"to":{"change":3,"start":471,"end":527},"introduced_by":3}],"inode":{"change":3,"pos":3238}},"ins_contents":[{"Add":"unsafe fn object_drop_front(e: Box>, target: TypeId) {"}],"del_contents":[{"Del":"unsafe fn object_drop_front(e: Box>) {\n"}]}},{"Edit":{"inode":{"change":3,"pos":3238},"path":"src/error.rs","line":422,"atom":{"NewVertex":{"up_context":[{"change":3,"pos":725}],"down_context":[{"change":3,"pos":725}],"flag":"BLOCK","start":595,"end":615,"inode":{"change":3,"pos":3238}}},"contents":[{"Add":" let _ = target;"}]}},{"Edit":{"inode":{"change":3,"pos":3238},"path":"src/error.rs","line":466,"atom":{"NewVertex":{"up_context":[{"change":2,"pos":1731}],"down_context":[{"change":3,"pos":2091}],"flag":"BLOCK","start":616,"end":773,"inode":{"change":3,"pos":3238}}},"contents":[{"Add":"}"},{"Add":""},{"Add":"unsafe fn context_is(target: TypeId) -> bool"},{"Add":"where"},{"Add":" C: 'static,"},{"Add":" E: 'static,"},{"Add":"{"},{"Add":" TypeId::of::() == target || TypeId::of::() == target"}]}},{"Replacement":{"inode":{"change":3,"pos":3238},"path":"src/error.rs","line":476,"ins":{"up_context":[{"change":3,"pos":2094}],"down_context":[{"change":3,"pos":9236}],"flag":"BLOCK","start":774,"end":2131,"inode":{"change":3,"pos":3238}},"del":{"edges":[{"previous":"","flag":"DELETED","from":{"change":3,"pos":674},"to":{"change":3,"start":9177,"end":9236},"introduced_by":3},{"previous":"","flag":"DELETED","from":{"change":3,"pos":2094},"to":{"change":3,"start":9177,"end":9236},"introduced_by":3},{"previous":"BLOCK","flag":"BLOCK | DELETED","from":{"change":3,"pos":9177},"to":{"change":3,"start":9177,"end":9236},"introduced_by":3}],"inode":{"change":3,"pos":3238}},"ins_contents":[{"Add":"unsafe fn context_downcast(e: &ErrorImpl<()>, target: TypeId) -> Option>"},{"Add":"where"},{"Add":" C: 'static,"},{"Add":" E: 'static,"},{"Add":"{"},{"Add":" if TypeId::of::() == target {"},{"Add":" let unerased = e as *const ErrorImpl<()> as *const ErrorImpl>;"},{"Add":" let addr = &(*unerased)._error.context as *const C as *mut ();"},{"Add":" Some(NonNull::new_unchecked(addr))"},{"Add":" } else if TypeId::of::() == target {"},{"Add":" let unerased = e as *const ErrorImpl<()> as *const ErrorImpl>;"},{"Add":" let addr = &(*unerased)._error.error as *const E as *mut ();"},{"Add":" Some(NonNull::new_unchecked(addr))"},{"Add":" } else {"},{"Add":" None"},{"Add":" }"},{"Add":"}"},{"Add":""},{"Add":"unsafe fn context_drop_rest(e: Box>, target: TypeId)"},{"Add":"where"},{"Add":" C: 'static,"},{"Add":" E: 'static,"},{"Add":"{"},{"Add":" // Called after downcasting by value to either the C or the E and doing a"},{"Add":" // ptr::read to take ownership of that value."},{"Add":" if TypeId::of::() == target {"},{"Add":" let unerased = mem::transmute::<"},{"Add":" Box>,"},{"Add":" Box, E>>>,"},{"Add":" >(e);"},{"Add":" drop(unerased);"},{"Add":" } else {"},{"Add":" let unerased = mem::transmute::<"},{"Add":" Box>,"},{"Add":" Box>>>,"},{"Add":" >(e);"},{"Add":" drop(unerased);"},{"Add":" }"},{"Add":"}"},{"Add":""},{"Add":"// repr C to ensure that E remains in the final position."}],"del_contents":[{"Del":"// repr C to ensure that `E` remains in the final position\n"}]}},{"Replacement":{"inode":{"change":3,"pos":3238},"path":"src/error.rs","line":521,"ins":{"up_context":[{"change":3,"pos":9352}],"down_context":[{"change":3,"pos":876}],"flag":"BLOCK","start":2132,"end":2239,"inode":{"change":3,"pos":3238}},"del":{"edges":[{"previous":"BLOCK","flag":"BLOCK | DELETED","from":{"change":3,"pos":9352},"to":{"change":3,"start":776,"end":876},"introduced_by":3}],"inode":{"change":3,"pos":3238}},"ins_contents":[{"Add":" // NOTE: Don't use directly. Use only through vtable. Erased type may have"},{"Add":" // different alignment."}],"del_contents":[{"Del":" // NOTE: Don't use directly. Use only through vtable. Erased type may have different alignment.\n"}]}},{"Edit":{"inode":{"change":3,"pos":3238},"path":"src/error.rs","line":526,"atom":{"NewVertex":{"up_context":[{"change":3,"pos":9369}],"down_context":[{"change":3,"pos":313}],"flag":"BLOCK","start":2240,"end":2392,"inode":{"change":3,"pos":3238}}},"contents":[{"Add":"// repr C to ensure that ContextError has the same layout as"},{"Add":"// ContextError, E> and ContextError>."},{"Add":"#[repr(C)]"}]}}],"owner":"yaahc","repo":"eyre","token":"xlle9CBSgUp69YzvYPZKVfNeJ+DuIxMd1GO5ykqQXpM=","login":null}

…

Dependencies

Change contents