Errors with the same span print the span once

[recrack]

Fix#4569.

[recrack]

• Source code 1

fn main() {
foo::bar::baz();
zoo::xar::caz();
}

before:

foo3.rs:2:5: 2:18 error: unresolved name
foo3.rs:2 foo::bar::baz();
^~~~~~~~~~~~~
foo3.rs:2:5: 2:18 error: use of undeclared module `foo::bar`
foo3.rs:2 foo::bar::baz();
^~~~~~~~~~~~~
foo3.rs:2:5: 2:18 error: unresolved name: `foo::bar::baz`.
foo3.rs:2 foo::bar::baz();
^~~~~~~~~~~~~
foo3.rs:3:5: 3:18 error: unresolved name
foo3.rs:3 zoo::xar::caz();
^~~~~~~~~~~~~
foo3.rs:3:5: 3:18 error: use of undeclared module `zoo::xar`
foo3.rs:3 zoo::xar::caz();
^~~~~~~~~~~~~
foo3.rs:3:5: 3:18 error: unresolved name: `zoo::xar::caz`.
foo3.rs:3 zoo::xar::caz();
^~~~~~~~~~~~~
error: aborting due to 6 previous errors

after:

foo3.rs:2:5: 2:18 error: unresolved name
foo3.rs:2:5: 2:18 error: use of undeclared module `foo::bar`
foo3.rs:2:5: 2:18 error: unresolved name: `foo::bar::baz`.
foo3.rs:2 foo::bar::baz();
^~~~~~~~~~~~~
foo3.rs:3:5: 3:18 error: unresolved name
foo3.rs:3:5: 3:18 error: use of undeclared module `zoo::xar`
foo3.rs:3:5: 3:18 error: unresolved name: `zoo::xar::caz`.
foo3.rs:3 zoo::xar::caz();
^~~~~~~~~~~~~
error: aborting due to 6 previous errors

• Source code 2

macro_rules! test(
($arg:ident) => (foo::$arg);
)
fn main() {
test!(bar);
}

before:

y.rs:2:21: 2:30 error: unresolved name
y.rs:2 ($arg:ident) => (foo::$arg);
^~~~~~~~~
y.rs:1:0: 3:1 note: in expansion of test!
y.rs:6:4: 6:15 note: expansion site
y.rs:2:21: 2:30 error: use of undeclared module `foo`
y.rs:2 ($arg:ident) => (foo::$arg);
^~~~~~~~~
y.rs:1:0: 3:1 note: in expansion of test!
y.rs:6:4: 6:15 note: expansion site
y.rs:2:21: 2:30 error: unresolved name: `foo::bar`.
y.rs:2 ($arg:ident) => (foo::$arg);
^~~~~~~~~
y.rs:1:0: 3:1 note: in expansion of test!
y.rs:6:4: 6:15 note: expansion site
error: aborting due to 3 previous errors

after:

y.rs:2:21: 2:30 error: unresolved name
y.rs:2:21: 2:30 error: use of undeclared module `foo`
y.rs:2:21: 2:30 error: unresolved name: `foo::bar`.
y.rs:2 ($arg:ident) => (foo::$arg);
^~~~~~~~~
y.rs:1:0: 3:1 note: in expansion of test!
y.rs:6:4: 6:15 note: expansion site
error: aborting due to 3 previous errors

[bstrie]

Awesome! Though I'd like to get a dev in here to confirm that they like this change wrt how notes get pushed to the end. In particular, how does this change handle borrowing errors, where the error itself is followed by a note like "loan of foo granted here" ? I hadn't considered this when I originally opened #4569, it may not even have been implemented back then.

[graydon]

I generally like this a lot. I'm not sure, as @bstrie mentions, how well this plays with borrow-check errors. Can you try a couple of those to see?

[recrack]

@bstrie , @graydon

Do you mean kind of this test?
i tested a couple of codes. ( code from github.com/mozilla/rust/issue )

• https://github.com/mozilla/rust/blob/master/src/test/compile-fail/borrowck-insert-during-each.rs

before

borrowck-insert-during-each.rs:27:4: 27:5 error: loan of dereference of mutable & pointer as mutable conflicts with prior loan
borrowck-insert-during-each.rs:27 f.n.insert(*a); //~ ERROR conflicts with prior loan
^
borrowck-insert-during-each.rs:26:5: 26:6 note: prior loan as mutable granted here
borrowck-insert-during-each.rs:26 do f.foo |a| { //~ NOTE prior loan as mutable granted here
^
error: aborting due to previous error

after ( note: prior loan as mutable granted here )

borrowck-insert-during-each.rs:26:5: 26:6 note: prior loan as mutable granted here
borrowck-insert-during-each.rs:26 do f.foo |a| { //~ NOTE prior loan as mutable granted here
^
borrowck-insert-during-each.rs:27:4: 27:5 error: loan of dereference of mutable & pointer as mutable conflicts with prior loan
borrowck-insert-during-each.rs:27 f.n.insert(*a); //~ ERROR conflicts with prior loan
^
error: aborting due to previous error

• loan.rs

struct MyStruct { numbers: int } impl MyStruct { fn takes_mut_self(&mut self, _x:int) {} fn takes_self(&self) ⟶ int { 42 fn also_takes_mut_self(&mut self) { self.takes_mut_self(self.takes_self()); } } fn main() {} 

before

loan.rs:11:28: 11:32 error: loan of dereference of mutable & pointer as immutable conflicts with prior loan
loan.rs:11 self.takes_mut_self(self.takes_self());
^~~~
loan.rs:11:8: 11:12 note: prior loan as mutable granted here
loan.rs:11 self.takes_mut_self(self.takes_self());
^~~~
error: aborting due to previous error

after ( note: prior loan as mutable granted here )

loan.rs:11:8: 11:12 note: prior loan as mutable granted here
loan.rs:11 self.takes_mut_self(self.takes_self());
^~~~
loan.rs:11:28: 11:32 error: loan of dereference of mutable & pointer as immutable conflicts with prior loan
loan.rs:11 self.takes_mut_self(self.takes_self());
^~~~
error: aborting due to previous error

[bstrie]

Hm, that definitely seems problematic. Is it difficult to have those notes printed after the errors rather than before them?

[graydon]

Yeah. Maybe I don't understand the structure of the patch, but I wonder the same question: can notes come after errors? Or does that undermine the whole logic of consolidating messages?

[recrack]

@bstrie , @graydon
Thank you for your comment! :)
i will check "notes come after errors".

[recrack]

@bstrie , @graydon

what kind of error message style do you want?

• Original Error Message

note.rs:8:32: 8:33 error: obsolete syntax: `/` lifetime notation
note.rs:8 fn next2(self) -> B/&self { let B { a: a } = self; B { a: a } }
^
note: instead of `&foo/bar`, write `&'foo bar`; instead of `bar/&foo`, write `&bar<'foo>
error: aborting due to previous error

• Style 1

note.rs:8:32: 8:33 error: obsolete syntax: `/` lifetime notation
note.rs:8 fn next2(self) -> B/&self { let B { a: a } = self; B { a: a } }
^
error: aborting due to previous error
note: instead of `&foo/bar`, write `&'foo bar`; instead of `bar/&foo`, write `&bar<'foo>

• Style 2

note.rs:8:32: 8:33 error: obsolete syntax: `/` lifetime notation
note.rs:8 fn next2(self) -> B/&self { let B { a: a } = self; B { a: a } }
^
note: instead of `&foo/bar`, write `&'foo bar`; instead of `bar/&foo`, write `&bar<'foo>
error: aborting due to previous error

[recrack]

I changed the order.

like this.(Style 2)

note.rs:8:32: 8:33 error: obsolete syntax: `/` lifetime notation
note.rs:8 fn next2(self) -> B/&self { let B { a: a } = self; B { a: a } }
^
note: instead of `&foo/bar`, write `&'foo bar`; instead of `bar/&foo`, write `&bar<'foo>
error: aborting due to previous error

[recrack]

r? @brson

[brson]

Thanks @recrack. Sorry for the delay.

[recrack]

@brson re-r?
I updated print error message case.

Fixed. Compile-test fail case.

failures:
[compile-fail] /home/ymin/share/rust/rustmozilla/src/test/compile-fail/deref-non-pointer.rs
[compile-fail] /home/ymin/share/rust/rustmozilla/src/test/compile-fail/for-loop-decl.rs
[compile-fail] /home/ymin/share/rust/rustmozilla/src/test/compile-fail/issue-2370-2.rs
[compile-fail] /home/ymin/share/rust/rustmozilla/src/test/compile-fail/issue-2370.rs
result: FAILED. 582 passed; 4 failed; 43 ignored

• Original Log Message

compile-fail/issue-2370.rs:18:11: 18:16 error: can only dereference structs with one anonymous field
compile-fail/issue-2370.rs:18 error!(*nyan);
^~~~~
note: in expansion of fmt!
<core-macros>:6:24: 6:43 note: expansion site
<core-macros>:4:4: 11:5 note: in expansion of error!
compile-fail/issue-2370.rs:18:4: 18:18 note: expansion site
error: aborting due to previous error

• Before ( My old error message )

compile-fail/issue-2370.rs:18:11: 18:16 error: internal compiler error: 0'th deref is of a non-deref'able type `cat`
compile-fail/issue-2370.rs:18 error!(*nyan);
^~~~~
note: in expansion of fmt!
<core-macros>:6:24: 6:43 note: expansion site
<core-macros>:4:4: 11:5 note: in expansion of error!
compile-fail/issue-2370.rs:18:4: 18:18 note: expansion site

• After (My new error message )

compile-fail/issue-2370.rs:18:11: 18:16 error: can only dereference structs with one anonymous field
compile-fail/issue-2370.rs:18:11: 18:16 error: internal compiler error: 0'th deref is of a non-deref'able type `cat`
compile-fail/issue-2370.rs:18 error!(*nyan);
^~~~~
note: in expansion of fmt!
<core-macros>:6:24: 6:43 note: expansion site
<core-macros>:4:4: 11:5 note: in expansion of error!
/home/ymin/share/rust/rustmozilla/src/test/compile-fail/issue-2370.rs:18:4: 18:18 note: expansion site
error: aborting due to 2 previous errors