json: Fix handling of NaN/Infinity #15192
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The JSON spec requires that these special values be serialized as null; the current serialization breaks any conformant JSON parser. So encoding needs to output "null", to_json on floating-point types can return Null as well as Number, and reading null when specifically expecting a number should be interpreted as NaN. There's no way to round-trip Infinity.
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I believe that @erickt has been working on some refactorings of serialization, so he may be best to ask about the duplication. |
bors
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The JSON spec requires that these special values be serialized as "null"; the current serialization breaks any conformant JSON parser. So encoding needs to output "null", `to_json` on floating-point types can return `Null` as well as `Number` values, and reading a `Null` value when specifically expecting a number should be interpreted as NaN. There's no way to round-trip Infinity through JSON.
This is my first attempt at both writing Rust and opening pull requests, so please dial your derp detector up to eleven when reviewing. A `rustc --test lib.rs` in `libserialize` passes all tests; a `make check` of the whole tree fails with the error below, but it doesn't look obviously related and the docs say that `make check` is known to be flaky on Windows.
---- [compile-fail] compile-fail/svh-change-significant-cfg.rs stdout ----
task '[compile-fail] compile-fail/svh-change-significant-cfg.rs' failed at 'called `Result::
unwrap()` on an `Err` value: couldn't create file (end of file (unknown error); path=i686-pc-mingw32
\test\compile-fail\svh-a-base.err; mode=truncate; access=write)', C:\msys\home\Mike\rust\src\libcore
\result.rs:545
Incidentally, it may just be my lack of familiarity with the language and its idioms, but the duplication between `Encoder`/`PrettyEncoder` had a distinct code smell to it. The size of the file (~3500 lines) also made it a bit hard to navigate. Has there been any discussion of refactoring and/or breaking it up? I couldn't find anything in Issues except the ancient #9028.
flip1995
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Jul 25, 2025
Fixes rust-lang/rust-clippy#15192 by adding checks for no_std while giving out Box recommendation ``` changelog: [`large_enum_variant`]: Dont suggest `Box` in `no_std` mode ```
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The JSON spec requires that these special values be serialized as "null"; the current serialization breaks any conformant JSON parser. So encoding needs to output "null",
to_jsonon floating-point types can returnNullas well asNumbervalues, and reading aNullvalue when specifically expecting a number should be interpreted as NaN. There's no way to round-trip Infinity through JSON.This is my first attempt at both writing Rust and opening pull requests, so please dial your derp detector up to eleven when reviewing. A
rustc --test lib.rsinlibserializepasses all tests; amake checkof the whole tree fails with the error below, but it doesn't look obviously related and the docs say thatmake checkis known to be flaky on Windows.Incidentally, it may just be my lack of familiarity with the language and its idioms, but the duplication between
Encoder/PrettyEncoderhad a distinct code smell to it. The size of the file (~3500 lines) also made it a bit hard to navigate. Has there been any discussion of refactoring and/or breaking it up? I couldn't find anything in Issues except the ancient #9028.