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The failure from Unwrapping an "Err" does not tell you what error it was #13379

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wackywendell opened this issue Apr 7, 2014 · 0 comments · Fixed by #13479
Closed

The failure from Unwrapping an "Err" does not tell you what error it was #13379

wackywendell opened this issue Apr 7, 2014 · 0 comments · Fixed by #13479

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@wackywendell
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Right now, if you call result.unwrap() for a variable result that is an Err, the program fails but does not tell you what was in the Err. For example:

fn main() {
    let test_err : Result<(), ~str> = Err(~"no reason whatsoever.");
    let _ = test_err.unwrap();
}

Output:
task '<main>' failed at 'called Result::unwrap()on anErr value', /build/rust-git/src/rust/src/libstd/result.rs:187

It would be convenient if failing on a Result<T, E : Show> also displayed the error it was failing on, so, for example, you could call let value = result.unwrap() in the main function of a program and know that it would tell you not only if an error occurred but also what that error was.
@Ryman Ryman mentioned this issue Apr 12, 2014
Merged
@sfackler sfackler mentioned this issue Apr 12, 2014
Merged
sfackler added a commit to sfackler/rust that referenced this issue Apr 14, 2014
@sfackler
Make Result::{unwrap, unwrap_err} require Show
eb0473d 
`foo.ok().unwrap()` and `foo.err().unwrap()` are the fallbacks for types
that aren't `Show`.

Closes rust-lang#13379
bors added a commit that referenced this issue Apr 14, 2014
@bors
auto merge of #13479 : sfackler/rust/result-unwrap, r=cmr
40a9797 
`foo.ok().unwrap()` and `foo.err().unwrap()` are the fallbacks for types
that aren't `Show`.

Closes #13379
compiler-errors pushed a commit to compiler-errors/rust that referenced this issue Oct 26, 2022
@bors
Auto merge of rust-lang#13399 - DropDemBits:assists-format-args-captu…
a2e4f78 
…re-pt2, r=Veykril

Migrate assists to format args captures, part 2

Continuation of rust-lang#13379

Migrates:

- `generate_constant`
- `generate_default_from_enum_variant`
- `generate_default_from_new`
- `generate_delegate_methods`
- `generate_deref`
- `generate_documentation_template`
- `generate_enum_is_method`
- `generate_enum_projection_method`
- `generate_from_impl_for_enum`
- `generate_function`
- `generate_getter`
- `generate_impl`
- `generate_new`
- `generate_setter`
notriddle pushed a commit to notriddle/rust that referenced this issue Nov 10, 2022
@bors
Auto merge of rust-lang#13379 - DropDemBits:ide-assists-format-args-c…
afe8f6b 
…apture, r=Veykril

internal: Migrate `ide_assists::utils` and `ide_assists::handlers` to use format arg captures (part 1)

This not only serves as making future migration to mutable syntax trees easier, it also finds out what needs to be migrated in the first place.

~~Aside from the first commit, subsequent commits are structured to only deal with one file/handler at a time.~~

This is the first of 3 PRs, migrating:

Utils:

- `gen_trait_fn_body`
- `render_snippet`
- `ReferenceConversion`
  - `convert_type`
  - `getter`

Handlers:

- `add_explicit_type`
- `add_return_type`
- `add_turbo_fish`
- `apply_demorgan`
- `auto_import`
- `convert_comment_block`
- `convert_integer_literal`
- `convert_into_to_from`
- `convert_iter_for_each_to_for`
- `convert_let_else_to_match`
- `convert_tuple_struct_to_named_struct`
- `convert_two_arm_bool_match_to_matches_macro`
- `destructure_tuple_binding`
- `extract_function`
- `extract_module`
- `extract_struct_from_enum_variant`
- `extract_type_alias`
- `extract_variable`
- `fix_visibility`
bors added a commit to rust-lang-ci/rust that referenced this issue Sep 24, 2024
@bors
Auto merge of rust-lang#13379 - alex-semenyuk:while_let_loop_fix_docu…
78bdd45 
…ment, r=dswij

Fix doc for `while_let_loop`

Fix doc for `while_let_loop`

changelog: none
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Make Result::{unwrap, unwrap_err} require Show sfackler/rust
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@wackywendell