{"header":{"message":"Move downcasting into vtable\n","description":null,"timestamp":"2019-10-27T23:58:51Z","authors":[{"email":"dtolnay@gmail.com","name":"David Tolnay"}]},"hash":"VWTWVVRECX62JABUZYFCTCPWTXXT3DB4635RIAGCKIQMGJ7VXRGAC","authors":[],"deps":{"hashes":[["VWTWVVRECX62JABUZYFCTCPWTXXT3DB4635RIAGCKIQMGJ7VXRGAC","Move downcasting into vtable\n"],["AA",null],["TJQE7LZGYT5FUB6LR2GGKIV3BHXAAOP2V2SMYNLUNCZNQ4JNF5PAC","Format with rustfmt 2019-09-08\n"],["TOXJRHV7ZUPHWXCA4TAG3YRBTIPUZQ5BNX34D3VD2JAIYLRN6XSAC","Move TypeId out of the Box allocation\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"],["RFSCYZWH7VQUGHAM374YUDGZGM5S4KT6NXWDMHXL4767SCRSL2DQC","Expand ContextError vtable to prepare for extending downcast support\n"],["RIKD63GT7RFV3UAV4BYD57GFXKXALWUP6J7AAHB3M6JVAZ3WFTXAC","Add conversion from Error to Box\n"],["IEMA7CQ74EKDOWZRKUCMJ5FIVAT42RMEQ5RUFM4WVNFYUNIAO7OAC","Add example to Error::downcast_ref\n"],["Z4YYQXEE4OQPF22I4LD7RVQIBKK67AHCYR6C35MANUCIC4P3EPYQC","Deallocate with the right Layout during downcast\n"],["UM7DFUYLW4HSMBUDZY3R6ZNJRSX2E75C4DYV3MJAU57EUCGE6JLAC","Rename Exception to Error\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"],["GZZOJ7ZUSBPI3HXIV5UCFNMCDAMZPPLISY2UDV73FDN74HZ3AWJAC","Format with rustfmt 2019-09-08\n"],["SZMWAJGIDYMGTPMWSW22NLZ3VRXA2BATFUTMSWOGH337EFYBTWQAC","Use Self in signatures of Error constructors\n"],["VSLQNAQBAGOJC2IV55V3W755UIPN47J4RTCCLCABRFFFUU5LT2JQC","Also move Error and Chain to get usable paths in diagnostics\n"],["CITEDKPB6MKVZUEYEDE5ZKTNVY35HCOAXKDPYG7YLLEOVFNMSRXQC","Import implementation from fehler 1.0.0-alpha.1\n"],["4SNDY6U7TDCVRCARTEQ7JLATJFDMUMEFV2GSLKMQJY7RFNPU5HDQC","Fix UB when accessing errors with large alignment\n"],["4G3IP4EELNSP2BTQRUJIMYFBNCITIUWUSSBAODV5Y5GPKNCCMMJAC","Explicitly specify all cast types in unsafe code\n"],["EXRAFG37562NH775A4LDPP5FNKXLPLIZSJ3FCOBINUDKRFBJHCXAC","Move trait bounds to where-clauses\n\nI find it more readable how this appears in rustdoc.\n"],["O557J2CNZMAHKGGCT3Y7LH5XORK63D2YOUCALWYB76CHVLJRSDBQC","Simplify downcast_ref and downcast_mut\n"],["W655S25G7CGI4XOZ2PKITKTH26VJ4QMZFRV2RPYNI4KIUJOIGVMAC","Change all remaining exception related wording\n"],["3LI5FAF5ULXOWBMTG4XCUOMUPVROSFDY6FWGE574OH4JGPMOPNVAC","Import std::error::Error as StdError\n\nTo avoid name collisions when renaming Exception to Error.\n"],["NPOFDGQF4CE72IZBT5Y7KPIBHWPPNOEPBYD5RTUHSVUJ2W4XFRVQC","Deallocate ErrorImpl with the right Layout\n"]],"deps":["TJQE7LZGYT5FUB6LR2GGKIV3BHXAAOP2V2SMYNLUNCZNQ4JNF5PAC","TOXJRHV7ZUPHWXCA4TAG3YRBTIPUZQ5BNX34D3VD2JAIYLRN6XSAC","BA4YE6QGRTYONATHUP347OFUBUCWXQPNZ6Q5DIQ2DLJLRZJ6AC4AC","RFSCYZWH7VQUGHAM374YUDGZGM5S4KT6NXWDMHXL4767SCRSL2DQC"],"known":["CITEDKPB6MKVZUEYEDE5ZKTNVY35HCOAXKDPYG7YLLEOVFNMSRXQC","GZZOJ7ZUSBPI3HXIV5UCFNMCDAMZPPLISY2UDV73FDN74HZ3AWJAC","3LI5FAF5ULXOWBMTG4XCUOMUPVROSFDY6FWGE574OH4JGPMOPNVAC","UM7DFUYLW4HSMBUDZY3R6ZNJRSX2E75C4DYV3MJAU57EUCGE6JLAC","W655S25G7CGI4XOZ2PKITKTH26VJ4QMZFRV2RPYNI4KIUJOIGVMAC","EXRAFG37562NH775A4LDPP5FNKXLPLIZSJ3FCOBINUDKRFBJHCXAC","SZMWAJGIDYMGTPMWSW22NLZ3VRXA2BATFUTMSWOGH337EFYBTWQAC","IEMA7CQ74EKDOWZRKUCMJ5FIVAT42RMEQ5RUFM4WVNFYUNIAO7OAC","T64LKJ2RTUDFYSJQI7KF4WHZYXZHNEGNOS7ZMMCRIQZ4YN5LOOMAC","NPOFDGQF4CE72IZBT5Y7KPIBHWPPNOEPBYD5RTUHSVUJ2W4XFRVQC","O557J2CNZMAHKGGCT3Y7LH5XORK63D2YOUCALWYB76CHVLJRSDBQC","Z4YYQXEE4OQPF22I4LD7RVQIBKK67AHCYR6C35MANUCIC4P3EPYQC","RIKD63GT7RFV3UAV4BYD57GFXKXALWUP6J7AAHB3M6JVAZ3WFTXAC","4SNDY6U7TDCVRCARTEQ7JLATJFDMUMEFV2GSLKMQJY7RFNPU5HDQC","4G3IP4EELNSP2BTQRUJIMYFBNCITIUWUSSBAODV5Y5GPKNCCMMJAC","VSLQNAQBAGOJC2IV55V3W755UIPN47J4RTCCLCABRFFFUU5LT2JQC"]},"hunks":[{"Replacement":{"inode":{"change":6,"pos":3238},"path":"src/error.rs","line":8,"ins":{"up_context":[{"change":6,"pos":3419}],"down_context":[{"change":6,"pos":3931}],"flag":"BLOCK","start":0,"end":31,"inode":{"change":6,"pos":3238}},"del":{"edges":[{"previous":"BLOCK","flag":"BLOCK | DELETED","from":{"change":6,"pos":3419},"to":{"change":6,"start":3419,"end":3433},"introduced_by":6}],"inode":{"change":6,"pos":3238}},"ins_contents":[{"Add":"use std::ptr::{self, NonNull};"}],"del_contents":[{"Del":"use std::ptr;\n"}]}},{"Edit":{"inode":{"change":6,"pos":3238},"path":"src/error.rs","line":37,"atom":{"NewVertex":{"up_context":[{"change":3,"pos":300}],"down_context":[{"change":3,"pos":300}],"flag":"BLOCK","start":32,"end":83,"inode":{"change":6,"pos":3238}}},"contents":[{"Add":" object_downcast: object_downcast::,"}]}},{"Edit":{"inode":{"change":6,"pos":3238},"path":"src/error.rs","line":56,"atom":{"NewVertex":{"up_context":[{"change":3,"pos":814}],"down_context":[{"change":3,"pos":814}],"flag":"BLOCK","start":84,"end":135,"inode":{"change":6,"pos":3238}}},"contents":[{"Add":" object_downcast: object_downcast::,"}]}},{"Edit":{"inode":{"change":6,"pos":3238},"path":"src/error.rs","line":76,"atom":{"NewVertex":{"up_context":[{"change":3,"pos":1395}],"down_context":[{"change":3,"pos":1395}],"flag":"BLOCK","start":136,"end":187,"inode":{"change":6,"pos":3238}}},"contents":[{"Add":" object_downcast: object_downcast::,"}]}},{"Edit":{"inode":{"change":6,"pos":3238},"path":"src/error.rs","line":98,"atom":{"NewVertex":{"up_context":[{"change":5,"pos":689}],"down_context":[{"change":5,"pos":689}],"flag":"BLOCK","start":188,"end":256,"inode":{"change":6,"pos":3238}}},"contents":[{"Add":" object_downcast: object_downcast::>,"}]}},{"Edit":{"inode":{"change":6,"pos":3238},"path":"src/error.rs","line":198,"atom":{"NewVertex":{"up_context":[{"change":4,"pos":474}],"down_context":[{"change":4,"pos":474}],"flag":"BLOCK","start":257,"end":329,"inode":{"change":6,"pos":3238}}},"contents":[{"Add":" object_downcast: object_downcast::>,"}]}},{"Replacement":{"inode":{"change":6,"pos":3238},"path":"src/error.rs","line":277,"ins":{"up_context":[{"change":6,"pos":1036}],"down_context":[{"change":6,"pos":84}],"flag":"BLOCK","start":330,"end":568,"inode":{"change":6,"pos":3238}},"del":{"edges":[{"previous":"BLOCK","flag":"BLOCK | DELETED","from":{"change":6,"pos":1036},"to":{"change":6,"start":56,"end":84},"introduced_by":6}],"inode":{"change":6,"pos":3238}},"ins_contents":[{"Add":" let target = TypeId::of::();"},{"Add":" unsafe {"},{"Add":" let addr = match (self.inner.vtable.object_downcast)(&self.inner, target) {"},{"Add":" Some(addr) => addr,"},{"Add":" None => return Err(self),"},{"Add":" };"}],"del_contents":[{"Del":" if self.is::() {\n"}]}},{"Replacement":{"inode":{"change":6,"pos":3238},"path":"src/error.rs","line":284,"ins":{"up_context":[{"change":6,"pos":133}],"down_context":[{"change":6,"pos":6882}],"flag":"BLOCK","start":569,"end":815,"inode":{"change":6,"pos":3238}},"del":{"edges":[{"previous":"","flag":"DELETED","from":{"change":6,"pos":133},"to":{"change":6,"start":6655,"end":6676},"introduced_by":6},{"previous":"BLOCK","flag":"BLOCK | DELETED","from":{"change":6,"pos":6655},"to":{"change":6,"start":6655,"end":6676},"introduced_by":6},{"previous":"BLOCK","flag":"BLOCK | DELETED","from":{"change":6,"pos":6676},"to":{"change":2,"start":0,"end":149},"introduced_by":2},{"previous":"","flag":"DELETED","from":{"change":6,"pos":111},"to":{"change":6,"start":218,"end":392},"introduced_by":6},{"previous":"","flag":"DELETED","from":{"change":6,"pos":112},"to":{"change":6,"start":218,"end":392},"introduced_by":6},{"previous":"","flag":"DELETED","from":{"change":2,"pos":149},"to":{"change":6,"start":218,"end":392},"introduced_by":2},{"previous":"BLOCK","flag":"BLOCK | DELETED","from":{"change":6,"pos":218},"to":{"change":6,"start":218,"end":392},"introduced_by":6},{"previous":"","flag":"DELETED","from":{"change":6,"pos":392},"to":{"change":6,"start":6803,"end":6882},"introduced_by":6},{"previous":"BLOCK","flag":"BLOCK | DELETED","from":{"change":6,"pos":6803},"to":{"change":6,"start":6803,"end":6882},"introduced_by":6}],"inode":{"change":6,"pos":3238}},"ins_contents":[{"Add":" let error = ptr::read(addr.cast::().as_ptr());"},{"Add":" let inner = ptr::read(&outer.inner);"},{"Add":" let erased = ManuallyDrop::into_inner(inner);"},{"Add":" (erased.vtable.object_drop_front)(erased);"},{"Add":" Ok(error)"}],"del_contents":[{"Del":" unsafe {\n"},{"Del":" let error = ptr::read(\n outer.inner.error() as *const (dyn StdError + Send + Sync) as *const E\n );\n"},{"Del":" let inner = ptr::read(&outer.inner);\n let erased = ManuallyDrop::into_inner(inner);\n (erased.vtable.object_drop_front)(erased);\n"},{"Del":" Ok(error)\n }\n } else {\n Err(self)\n"}]}},{"Replacement":{"inode":{"change":6,"pos":3238},"path":"src/error.rs","line":332,"ins":{"up_context":[{"change":6,"pos":1153}],"down_context":[{"change":6,"pos":1414}],"flag":"BLOCK","start":816,"end":1001,"inode":{"change":6,"pos":3238}},"del":{"edges":[{"previous":"","flag":"DELETED","from":{"change":6,"pos":1153},"to":{"change":6,"start":7036,"end":7064},"introduced_by":6},{"previous":"BLOCK","flag":"BLOCK | DELETED","from":{"change":6,"pos":7036},"to":{"change":6,"start":7036,"end":7064},"introduced_by":6},{"previous":"BLOCK","flag":"BLOCK | DELETED","from":{"change":6,"pos":7064},"to":{"change":2,"start":150,"end":281},"introduced_by":2},{"previous":"","flag":"DELETED","from":{"change":6,"pos":76},"to":{"change":6,"start":1380,"end":1414},"introduced_by":6},{"previous":"","flag":"DELETED","from":{"change":6,"pos":189},"to":{"change":6,"start":1380,"end":1414},"introduced_by":6},{"previous":"","flag":"DELETED","from":{"change":6,"pos":215},"to":{"change":6,"start":1380,"end":1414},"introduced_by":6},{"previous":"","flag":"DELETED","from":{"change":2,"pos":281},"to":{"change":6,"start":1380,"end":1414},"introduced_by":2},{"previous":"","flag":"DELETED","from":{"change":6,"pos":1343},"to":{"change":6,"start":1380,"end":1414},"introduced_by":6},{"previous":"BLOCK","flag":"BLOCK | DELETED","from":{"change":6,"pos":7148},"to":{"change":6,"start":1380,"end":1414},"introduced_by":6}],"inode":{"change":6,"pos":3238}},"ins_contents":[{"Add":" let target = TypeId::of::();"},{"Add":" unsafe {"},{"Add":" let addr = (self.inner.vtable.object_downcast)(&self.inner, target)?;"},{"Add":" Some(&*addr.cast::().as_ptr())"}],"del_contents":[{"Del":" if self.is::() {\n"},{"Del":" Some(unsafe {\n &*(self.inner.error() as *const (dyn StdError + Send + Sync) as *const E)\n })\n"},{"Del":" } else {\n None\n"}]}},{"Replacement":{"inode":{"change":6,"pos":3238},"path":"src/error.rs","line":344,"ins":{"up_context":[{"change":6,"pos":1278}],"down_context":[{"change":6,"pos":1459}],"flag":"BLOCK","start":1002,"end":1191,"inode":{"change":6,"pos":3238}},"del":{"edges":[{"previous":"","flag":"DELETED","from":{"change":6,"pos":1278},"to":{"change":6,"start":7332,"end":7360},"introduced_by":6},{"previous":"BLOCK","flag":"BLOCK | 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DELETED","from":{"change":6,"pos":7448},"to":{"change":6,"start":1425,"end":1459},"introduced_by":6}],"inode":{"change":6,"pos":3238}},"ins_contents":[{"Add":" let target = TypeId::of::();"},{"Add":" unsafe {"},{"Add":" let addr = (self.inner.vtable.object_downcast)(&self.inner, target)?;"},{"Add":" Some(&mut *addr.cast::().as_ptr())"}],"del_contents":[{"Del":" if self.is::() {\n"},{"Del":" Some(unsafe {\n &mut *(self.inner.error_mut() as *mut (dyn StdError + Send + Sync) as *mut E)\n })\n"},{"Del":" } else {\n None\n"}]}},{"Edit":{"inode":{"change":6,"pos":3238},"path":"src/error.rs","line":408,"atom":{"NewVertex":{"up_context":[{"change":3,"pos":1987}],"down_context":[{"change":6,"pos":520}],"flag":"BLOCK","start":1192,"end":1271,"inode":{"change":6,"pos":3238}}},"contents":[{"Add":" object_downcast: unsafe fn(&ErrorImpl<()>, TypeId) -> Option>,"}]}},{"Replacement":{"inode":{"change":6,"pos":3238},"path":"src/error.rs","line":447,"ins":{"up_context":[{"change":6,"pos":674}],"down_context":[{"change":3,"pos":2035}],"flag":"BLOCK","start":1272,"end":1465,"inode":{"change":6,"pos":3238}},"del":{"edges":[{"previous":"BLOCK","flag":"BLOCK | DELETED","from":{"change":6,"pos":674},"to":{"change":3,"start":1988,"end":2035},"introduced_by":3}],"inode":{"change":6,"pos":3238}},"ins_contents":[{"Add":"unsafe fn object_is(target: TypeId) -> bool"},{"Add":"where"},{"Add":" E: 'static,"},{"Add":"{"},{"Add":" TypeId::of::() == target"},{"Add":"}"},{"Add":""},{"Add":"unsafe fn object_downcast(e: &ErrorImpl<()>, target: TypeId) -> Option>"}],"del_contents":[{"Del":"unsafe fn object_is(target: TypeId) -> bool\n"}]}},{"Replacement":{"inode":{"change":6,"pos":3238},"path":"src/error.rs","line":456,"ins":{"up_context":[{"change":3,"pos":2041}],"down_context":[{"change":3,"pos":2057}],"flag":"BLOCK","start":1466,"end":1482,"inode":{"change":6,"pos":3238}},"del":{"edges":[{"previous":"BLOCK","flag":"BLOCK | DELETED","from":{"change":3,"pos":2041},"to":{"change":3,"start":2041,"end":2057},"introduced_by":3}],"inode":{"change":6,"pos":3238}},"ins_contents":[{"Add":" E: 'static,"}],"del_contents":[{"Del":" T: 'static,\n"}]}},{"Replacement":{"inode":{"change":6,"pos":3238},"path":"src/error.rs","line":458,"ins":{"up_context":[{"change":3,"pos":2059}],"down_context":[{"change":3,"pos":2091}],"flag":"BLOCK","start":1483,"end":1731,"inode":{"change":6,"pos":3238}},"del":{"edges":[{"previous":"BLOCK","flag":"BLOCK | DELETED","from":{"change":3,"pos":2059},"to":{"change":3,"start":2059,"end":2091},"introduced_by":3}],"inode":{"change":6,"pos":3238}},"ins_contents":[{"Add":" if TypeId::of::() == target {"},{"Add":" let unerased = e as *const ErrorImpl<()> as *const ErrorImpl;"},{"Add":" let addr = &(*unerased)._error as *const E as *mut ();"},{"Add":" Some(NonNull::new_unchecked(addr))"},{"Add":" } else {"},{"Add":" None"},{"Add":" }"}],"del_contents":[{"Del":" TypeId::of::() == target\n"}]}}],"owner":"yaahc","repo":"eyre","token":"qhZKHjkV6zHIvoLyOeUmweQV+TZgRMZAxl762figvwk=","login":null}

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