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

2 files changed, 0 insertions, 11 deletions

diff --git a/compiler/rustc_interface/src/passes.rs b/compiler/rustc_interface/src/passes.rs
index e6c9c6693c5..3c867e308c4 100644
--- a/compiler/rustc_interface/src/passes.rs
+++ b/compiler/rustc_interface/src/passes.rs
@@ -27,7 +27,6 @@ use rustc_passes::{self, hir_stats, layout_test};
 use rustc_plugin_impl as plugin;
 use rustc_query_impl::{OnDiskCache, Queries as TcxQueries};
 use rustc_resolve::{Resolver, ResolverArenas};
-use rustc_serialize::json;
 use rustc_session::config::{CrateType, Input, OutputFilenames, OutputType};
 use rustc_session::cstore::{MetadataLoader, MetadataLoaderDyn};
 use rustc_session::output::{filename_for_input, filename_for_metadata};
@@ -59,10 +58,6 @@ pub fn parse<'a>(sess: &'a Session, input: &Input) -> PResult<'a, ast::Crate> {
         }
     })?;
 
-    if sess.opts.debugging_opts.ast_json_noexpand {
-        println!("{}", json::as_json(&krate));
-    }
-
     if sess.opts.debugging_opts.input_stats {
         eprintln!("Lines of code:             {}", sess.source_map().count_lines());
         eprintln!("Pre-expansion node count:  {}", count_nodes(&krate));
@@ -423,10 +418,6 @@ pub fn configure_and_expand(
         hir_stats::print_ast_stats(&krate, "POST EXPANSION AST STATS");
     }
 
-    if sess.opts.debugging_opts.ast_json {
-        println!("{}", json::as_json(&krate));
-    }
-
     resolver.resolve_crate(&krate);
 
     // Needs to go *after* expansion to be able to check the results of macro expansion.
diff --git a/compiler/rustc_interface/src/tests.rs b/compiler/rustc_interface/src/tests.rs
index 1327bf6fcd4..a178cca6d10 100644
--- a/compiler/rustc_interface/src/tests.rs
+++ b/compiler/rustc_interface/src/tests.rs
@@ -644,8 +644,6 @@ fn test_debugging_options_tracking_hash() {
     // Make sure that changing an [UNTRACKED] option leaves the hash unchanged.
     // This list is in alphabetical order.
     untracked!(assert_incr_state, Some(String::from("loaded")));
-    untracked!(ast_json, true);
-    untracked!(ast_json_noexpand, true);
     untracked!(borrowck, String::from("other"));
     untracked!(deduplicate_diagnostics, false);
     untracked!(dep_tasks, true);