Auto merge of #85993 - bjorn3:serde_json, r=wesleywiser

Remove all json handling from rustc_serialize

Json is now handled using serde_json. Where appropriate I have replaced json usage with binary serialization (rmeta files) or manual string formatting (emcc linker arg generation).

This allowed for removing and simplifying a lot of code, which hopefully results in faster serialization/deserialization and faster compiles of rustc itself.

Where sensible we now use serde. Metadata and incr cache serialization keeps using a heavily modified (compared to crates.io) rustc-serialize version that in the future could probably be extended with zero-copy deserialization or other perf tricks that serde can't support due to supporting more than one serialization format.

Note that I had to remove `-Zast-json` and `-Zast-json-noexpand` as the relevant AST types don't implement `serde::Serialize`.

Fixes #40177

See also https://github.com/rust-lang/compiler-team/issues/418

1 files changed, 0 insertions, 10 deletions

diff --git a/compiler/rustc_serialize/src/opaque.rs b/compiler/rustc_serialize/src/opaque.rs
index 5e5cbacbcff..3bcb7cc3650 100644
--- a/compiler/rustc_serialize/src/opaque.rs
+++ b/compiler/rustc_serialize/src/opaque.rs
@@ -65,11 +65,6 @@ impl serialize::Encoder for Encoder {
     type Error = !;
 
     #[inline]
-    fn emit_unit(&mut self) -> EncodeResult {
-        Ok(())
-    }
-
-    #[inline]
     fn emit_usize(&mut self, v: usize) -> EncodeResult {
         write_leb128!(self, v, usize, write_usize_leb128)
     }
@@ -420,11 +415,6 @@ impl serialize::Encoder for FileEncoder {
     type Error = io::Error;
 
     #[inline]
-    fn emit_unit(&mut self) -> FileEncodeResult {
-        Ok(())
-    }
-
-    #[inline]
     fn emit_usize(&mut self, v: usize) -> FileEncodeResult {
         file_encoder_write_leb128!(self, v, usize, write_usize_leb128)
     }