Objects fields named Result generate code that (generally) won't compile

[colmanhumphrey]

Having a Result definition seems to create code that won't compile, if std::result::Result is needed.

Reproduction

A simplified schema that shows the issue (note: if you don't have the enum, or something that needs a result, it won't give the error):

{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "title": "Test",
  "type": "object",
  "properties": {
    "results": {
      "$ref": "#/definitions/MultipleResult"
    }
  },
  "definitions": {
    "MultipleResult": {
      "type": "object",
      "properties": {
        "results": {
          "type": "array",
          "items": {
            "$ref": "#/definitions/Result"
          }
        }
      }
    },
    "Result": {
      "type": "object",
      "properties": {
        "id": {
          "type": "string"
        }
      }
    },
    "SomeEnum": {
      "type": "string",
      "description": "",
      "enum": [
        "Arm1",
        "Arm2",
        "Arm3"
      ]
    }
  }
}

Gives:

error[E0107]: struct takes 0 generic arguments but 2 generic arguments were supplied
   --> src/lib.rs:136:33
    |
136 |     fn try_from(value: &str) -> Result<Self, self::error::ConversionError> {
    |                                 ^^^^^^------------------------------------ help: remove these generics
    |                                 |
    |                                 expected 0 generic arguments
    |
note: struct defined here, with 0 generic parameters
   --> src/lib.rs:78:12
    |
78  | pub struct Result {
    |            ^^^^^^

error[E0107]: struct takes 0 generic arguments but 2 generic arguments were supplied
   --> src/lib.rs:142:36
    |
142 |     fn try_from(value: &String) -> Result<Self, self::error::ConversionError> {
    |                                    ^^^^^^------------------------------------ help: remove these generics
    |                                    |
    |                                    expected 0 generic arguments
    |
note: struct defined here, with 0 generic parameters
   --> src/lib.rs:78:12
    |
78  | pub struct Result {
    |            ^^^^^^

error[E0107]: struct takes 0 generic arguments but 2 generic arguments were supplied
   --> src/lib.rs:125:33
    |
125 |     fn from_str(value: &str) -> Result<Self, self::error::ConversionError> {
    |                                 ^^^^^^------------------------------------ help: remove these generics
    |                                 |
    |                                 expected 0 generic arguments
    |
note: struct defined here, with 0 generic parameters
   --> src/lib.rs:78:12
    |
78  | pub struct Result {
    |            ^^^^^^

error[E0053]: method `from_str` has an incompatible type for trait
   --> src/lib.rs:125:33
    |
125 |     fn from_str(value: &str) -> Result<Self, self::error::ConversionError> {
    |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |                                 |
    |                                 expected `Result<SomeEnum, ConversionError>`, found `Result`
    |                                 help: change the output type to match the trait: `std::result::Result<SomeEnum, ConversionError>`
    |
    = note: expected signature `fn(&_) -> std::result::Result<SomeEnum, ConversionError>`
               found signature `fn(&_) -> Result`

error[E0053]: method `try_from` has an incompatible type for trait
   --> src/lib.rs:136:33
    |
136 |     fn try_from(value: &str) -> Result<Self, self::error::ConversionError> {
    |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |                                 |
    |                                 expected `Result<SomeEnum, ConversionError>`, found `Result`
    |                                 help: change the output type to match the trait: `std::result::Result<SomeEnum, ConversionError>`
    |
    = note: expected signature `fn(&_) -> std::result::Result<SomeEnum, ConversionError>`
               found signature `fn(&_) -> Result`

error[E0053]: method `try_from` has an incompatible type for trait
   --> src/lib.rs:142:36
    |
142 |     fn try_from(value: &String) -> Result<Self, self::error::ConversionError> {
    |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |                                    |
    |                                    expected `Result<SomeEnum, ConversionError>`, found `Result`
    |                                    help: change the output type to match the trait: `std::result::Result<SomeEnum, ConversionError>`
    |
    = note: expected signature `fn(&std::string::String) -> std::result::Result<SomeEnum, ConversionError>`
               found signature `fn(&std::string::String) -> Result`

error[E0107]: struct takes 0 generic arguments but 2 generic arguments were supplied
   --> src/lib.rs:148:35
    |
148 |     fn try_from(value: String) -> Result<Self, self::error::ConversionError> {
    |                                   ^^^^^^------------------------------------ help: remove these generics
    |                                   |
    |                                   expected 0 generic arguments
    |
note: struct defined here, with 0 generic parameters
   --> src/lib.rs:78:12
    |
78  | pub struct Result {
    |            ^^^^^^

error[E0053]: method `try_from` has an incompatible type for trait
   --> src/lib.rs:148:35
    |
148 |     fn try_from(value: String) -> Result<Self, self::error::ConversionError> {
    |                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |                                   |
    |                                   expected `Result<SomeEnum, ConversionError>`, found `Result`
    |                                   help: change the output type to match the trait: `std::result::Result<SomeEnum, ConversionError>`
    |
    = note: expected signature `fn(std::string::String) -> std::result::Result<SomeEnum, ConversionError>`
               found signature `fn(std::string::String) -> Result`

error[E0308]: mismatched types
   --> src/lib.rs:127:23
    |
125 |     fn from_str(value: &str) -> Result<Self, self::error::ConversionError> {
    |                                 ------------------------------------------ expected `Result` because of return type
126 |         match value {
127 |             "Arm1" => Ok(Self::Arm1),
    |                       ^^^^^^^^^^^^^^ expected `Result`, found `Result<SomeEnum, _>`
    |
    = note: `std::result::Result<SomeEnum, _>` and `Result` have similar names, but are actually distinct types
note: `std::result::Result<SomeEnum, _>` is defined in crate `core`
   --> /Users/colmanhumphrey/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/core/src/result.rs:502:1
    |
502 | pub enum Result<T, E> {
    | ^^^^^^^^^^^^^^^^^^^^^
note: `Result` is defined in the current crate
   --> src/lib.rs:78:1
    |
78  | pub struct Result {
    | ^^^^^^^^^^^^^^^^^

error[E0308]: mismatched types
   --> src/lib.rs:137:9
    |
136 |     fn try_from(value: &str) -> Result<Self, self::error::ConversionError> {
    |                                 ------------------------------------------ expected `Result` because of return type
137 |         value.parse()
    |         ^^^^^^^^^^^^^ expected `Result`, found `Result<_, _>`
    |
    = note: `std::result::Result<_, _>` and `Result` have similar names, but are actually distinct types
note: `std::result::Result<_, _>` is defined in crate `core`
   --> /Users/colmanhumphrey/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/core/src/result.rs:502:1
    |
502 | pub enum Result<T, E> {
    | ^^^^^^^^^^^^^^^^^^^^^
note: `Result` is defined in the current crate
   --> src/lib.rs:78:1
    |
78  | pub struct Result {
    | ^^^^^^^^^^^^^^^^^
help: consider using `Result::expect` to unwrap the `std::result::Result<_, _>` value, panicking if the value is a `Result::Err`
    |
137 |         value.parse().expect("REASON")
    |                      +++++++++++++++++

error[E0308]: mismatched types
   --> src/lib.rs:143:9
    |
142 |     fn try_from(value: &String) -> Result<Self, self::error::ConversionError> {
    |                                    ------------------------------------------ expected `Result` because of return type
143 |         value.parse()
    |         ^^^^^^^^^^^^^ expected `Result`, found `Result<_, _>`
    |
    = note: `std::result::Result<_, _>` and `Result` have similar names, but are actually distinct types
note: `std::result::Result<_, _>` is defined in crate `core`
   --> /Users/colmanhumphrey/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/core/src/result.rs:502:1
    |
502 | pub enum Result<T, E> {
    | ^^^^^^^^^^^^^^^^^^^^^
note: `Result` is defined in the current crate
   --> src/lib.rs:78:1
    |
78  | pub struct Result {
    | ^^^^^^^^^^^^^^^^^
help: consider using `Result::expect` to unwrap the `std::result::Result<_, _>` value, panicking if the value is a `Result::Err`
    |
143 |         value.parse().expect("REASON")
    |                      +++++++++++++++++

error[E0308]: mismatched types
   --> src/lib.rs:149:9
    |
148 |     fn try_from(value: String) -> Result<Self, self::error::ConversionError> {
    |                                   ------------------------------------------ expected `Result` because of return type
149 |         value.parse()
    |         ^^^^^^^^^^^^^ expected `Result`, found `Result<_, _>`
    |
    = note: `std::result::Result<_, _>` and `Result` have similar names, but are actually distinct types
note: `std::result::Result<_, _>` is defined in crate `core`
   --> /Users/colmanhumphrey/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/core/src/result.rs:502:1
    |
502 | pub enum Result<T, E> {
    | ^^^^^^^^^^^^^^^^^^^^^
note: `Result` is defined in the current crate
   --> src/lib.rs:78:1
    |
78  | pub struct Result {
    | ^^^^^^^^^^^^^^^^^
help: consider using `Result::expect` to unwrap the `std::result::Result<_, _>` value, panicking if the value is a `Result::Err`
    |
149 |         value.parse().expect("REASON")
    |                      +++++++++++++++++

Some errors have detailed explanations: E0053, E0107, E0308.
For more information about an error, try `rustc --explain E0053`.
error: could not compile `inspection-schema` (lib) due to 12 previous errors

Solve

I think an explicit Result, like #458, should hopefully solve it.

(meanwhile, I will probably change my field name...)

Thanks!

[ahl]

Thanks for the bug report. It sounds like we should fully qualify our use of std::result::Result to avoid ambiguity.