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

wackywendell · 2014-04-07T15:50:48Z

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.

The text was updated successfully, but these errors were encountered:

`foo.ok().unwrap()` and `foo.err().unwrap()` are the fallbacks for types that aren't `Show`. Closes rust-lang#13379

`foo.ok().unwrap()` and `foo.err().unwrap()` are the fallbacks for types that aren't `Show`. Closes #13379

…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`

…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`

Ryman mentioned this issue Apr 12, 2014

libstd: Add unwrap_or and unwrap_or_handle to Result #13475

Merged

sfackler mentioned this issue Apr 12, 2014

Make Result::{unwrap, unwrap_err} require Show #13479

Merged

sfackler added a commit to sfackler/rust that referenced this issue Apr 14, 2014

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

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

bors closed this as completed in #13479 Apr 14, 2014

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

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

wackywendell commented Apr 7, 2014

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

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

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wackywendell commented Apr 7, 2014