[NLL] Use better span for initializing a variable twice #51926

matthewjasper · 2018-06-29T23:09:34Z

When assigning to a (projection from a) local immutable local which starts initialised (everything except let PATTERN;):

Point to the declaration of that local
Make the error message refer to the local, rather than the projection.

r? @nikomatsakis

rust-highfive · 2018-06-29T23:28:04Z

The job x86_64-gnu-llvm-3.9 of your PR failed on Travis (raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

[00:07:21]    Compiling proc_macro v0.0.0 (file:///checkout/src/libproc_macro)
[00:07:42]    Compiling syntax_ext v0.0.0 (file:///checkout/src/libsyntax_ext)
[00:14:11]    Compiling rustc_mir v0.0.0 (file:///checkout/src/librustc_mir)
[00:14:11]    Compiling rustc_typeck v0.0.0 (file:///checkout/src/librustc_typeck)
[00:14:11] error: expected one of `=>`, `if`, or `|`, found `Some`
[00:14:11]    --> librustc_mir/borrow_check/error_reporting.rs:646:13
[00:14:11]     |
[00:14:11] 645 |             }))), ..})
[00:14:11]     |                       - expected one of `=>`, `if`, or `|` here
[00:14:11] 646 |             Some(LocalDecl { is_user_variable: None, .. })
[00:14:11]     |             ^^^^ unexpected token
[00:14:11] 
[00:14:13] error: unused imports: `BindingForm`, `ClearCrossCrate`
[00:14:13]   --> librustc_mir/borrow_check/error_reporting.rs:13:18
[00:14:13]    |
[00:14:13] 13 | use rustc::mir::{BindingForm, BorrowKind, ClearCrossCrate, Field, Local};
[00:14:13]    |
[00:14:13]    = note: `-D unused-imports` implied by `-D warnings`
[00:14:13] 
[00:14:13] 
[00:14:13] error: unused import: `LocalDecl`
[00:14:13]   --> librustc_mir/borrow_check/error_reporting.rs:14:18
[00:14:13]    |
[00:14:13] 14 | use rustc::mir::{LocalDecl, LocalKind, Location, Operand, Place};
[00:14:13] 
[00:14:13] 
[00:14:13] error: unused import: `rustc::mir::VarBindingForm`
[00:14:13]   --> librustc_mir/borrow_check/error_reporting.rs:16:5
[00:14:13]    |
[00:14:13] 16 | use rustc::mir::VarBindingForm;
[00:14:13] 
[00:14:15] error: unreachable statement
[00:14:15]    --> librustc_mir/borrow_check/error_reporting.rs:651:9
[00:14:15]     |
[00:14:15]     |
[00:14:15] 651 | /         let mut err = self.tcx.cannot_reassign_immutable(
[00:14:15] 652 | |             span,
[00:14:15] 653 | |             place_description.as_ref().map(AsRef::as_ref).unwrap_or("_"),
[00:14:15] 654 | |             from_arg,
[00:14:15] 655 | |             Origin::Mir,
[00:14:15] 656 | |         );
[00:14:15]     |
[00:14:15]     = note: `-D unreachable-code` implied by `-D warnings`
[00:14:15] 
[00:14:24] error: aborting due to 5 previous errors
[00:14:24] error: aborting due to 5 previous errors
[00:14:24] 
[00:14:24] error: Could not compile `rustc_mir`.
[00:14:24] 
[00:14:24] Caused by:
[00:14:24]   process didn't exit successfully: `/checkout/obj/build/bootstrap/debug/rustc --crate-name rustc_mir librustc_mir/lib.rs --color always --error-format json --crate-type dylib --emit=dep-info,link -C prefer-dynamic -C opt-level=2 -C metadata=cfff5c37c787835a -C extra-filename=-cfff5c37c787835a --out-dir /checkout/obj/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps --target x86_64-unknown-linux-gnu -L dependency=/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps -L dependency=/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-rustc/release/deps --extern rustc_apfloat=/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps/librustc_apfloat-642a7efe79e24835.rlib --extern graphviz=/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps/libgraphviz-be994de8b3050feb.so --extern log_settings=/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps/liblog_settings-f16e9eee09cda644.rlib --extern rustc_target=/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps/librustc_target-58741ed9de9aae4f.so --extern rustc=/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps/librustc-f0ddda7cc3e4e4d5.so --extern syntax_pos=/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps/libsyntax_pos-fcb7f2ed7949c0c2.so --extern polonius_engine=/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps/libpolonius_engine-6e0be5cf77966185.rlib --extern syntax=/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps/libsyntax-b9c6a6d70ded088a.so --extern serialize=/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps/libserialize-5d0a8a65bb9fe29f.so --extern serialize=/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps/libserialize-5d0a8a65bb9fe29f.rlib --extern bitflags=/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps/libbitflags-99b4534960f92449.rlib --extern byteorder=/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps/libbyteorder-78ebc049d4f53f46.rlib --extern either=/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps/libeither-11fcd35bf55f48b3.rlib --extern arena=/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps/libarena-ccde2368d50449de.so --extern log=/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps/liblog-5073f1296cd24b67.rlib --extern rustc_data_structures=/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps/librustc_data_structures-a7df2fc298b4fb06.so --extern rustc_errors=/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps/librustc_errors-c73ed1030caf17c3.so -L native=/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/build/backtrace-sys-88673787176f9d86/out -L native=/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/build/miniz-sys-62d80197b9ec531e/out` (exit code: 101)
[00:16:12] error: build failed
[00:16:12] command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "build" "--target" "x86_64-unknown-linux-gnu" "-j" "4" "--release" "--locked" "--color" "always" "--features" " jemalloc" "--manifest-path" "/checkout/src/rustc/Cargo.toml" "--message-format" "json"
[00:16:12] expected success, got: exit code: 101
[00:16:12] expected success, got: exit code: 101
[00:16:12] thread 'main' panicked at 'cargo must succeed', bootstrap/compile.rs:1091:9
[00:16:12] travis_fold:end:stage0-rustc

[00:16:12] travis_time:end:stage0-rustc:start=1530314204991788950,finish=1530314881092018956,duration=676100230006

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN. (Feature Requests)

nikomatsakis · 2018-07-02T17:16:21Z

@bors r+

bors · 2018-07-02T17:16:22Z

📌 Commit c613aa5 has been approved by nikomatsakis

@nikomatsakis

…r=nikomatsakis [NLL] Use better span for initializing a variable twice Closes rust-lang#51217 When assigning to a (projection from a) local immutable local which starts initialised (everything except `let PATTERN;`): * Point to the declaration of that local * Make the error message refer to the local, rather than the projection. r? @nikomatsakis

bors · 2018-07-03T23:54:31Z

⌛ Testing commit c613aa5 with merge a739c51...

@nikomatsakis

[NLL] Use better span for initializing a variable twice Closes #51217 When assigning to a (projection from a) local immutable local which starts initialised (everything except `let PATTERN;`): * Point to the declaration of that local * Make the error message refer to the local, rather than the projection. r? @nikomatsakis

bors · 2018-07-04T01:59:25Z

☀️ Test successful - status-appveyor, status-travis
Approved by: nikomatsakis
Pushing a739c51 to master...

rust-highfive assigned nikomatsakis Jun 29, 2018

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jun 29, 2018

Improve error messages when assigning to a local that starts initialized

c613aa5

matthewjasper force-pushed the Initialization-span branch from 2d1a92d to c613aa5 Compare June 30, 2018 10:06

nikomatsakis approved these changes Jul 2, 2018

View reviewed changes

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jul 2, 2018

Mark-Simulacrum mentioned this pull request Jul 2, 2018

Rollup of 12 pull requests #52001

Closed

bors merged commit c613aa5 into rust-lang:master Jul 4, 2018

matthewjasper deleted the Initialization-span branch September 3, 2018 21:32

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[NLL] Use better span for initializing a variable twice #51926

[NLL] Use better span for initializing a variable twice #51926

matthewjasper commented Jun 29, 2018

rust-highfive commented Jun 29, 2018

nikomatsakis commented Jul 2, 2018

bors commented Jul 2, 2018

bors commented Jul 3, 2018

bors commented Jul 4, 2018

[NLL] Use better span for initializing a variable twice #51926

[NLL] Use better span for initializing a variable twice #51926

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matthewjasper commented Jun 29, 2018

rust-highfive commented Jun 29, 2018

nikomatsakis commented Jul 2, 2018

bors commented Jul 2, 2018

bors commented Jul 3, 2018

bors commented Jul 4, 2018