From 540f95d9fad41a605e4c8b898d77f47374a76cbd Mon Sep 17 00:00:00 2001
From: Manish Goregaokar <manishsmail@gmail.com>
Date: Wed, 24 Jan 2018 11:50:30 +0530
Subject: Add internal-only rustc_serialize_exclude_null attribute for making
 the field only exist in the json if the flag is passed

---
 src/libsyntax/feature_gate.rs | 5 +++++
 src/libsyntax/json.rs         | 2 ++
 src/libsyntax/lib.rs          | 1 +
 3 files changed, 8 insertions(+)

(limited to 'src/libsyntax')

diff --git a/src/libsyntax/feature_gate.rs b/src/libsyntax/feature_gate.rs
index 9a2560b0458..3e523fca92a 100644
--- a/src/libsyntax/feature_gate.rs
+++ b/src/libsyntax/feature_gate.rs
@@ -788,6 +788,11 @@ pub const BUILTIN_ATTRIBUTES: &'static [(&'static str, AttributeType, AttributeG
                                                        is just used for rustc unit tests \
                                                        and will never be stable",
                                                       cfg_fn!(rustc_attrs))),
+    ("rustc_serialize_exclude_null", Normal, Gated(Stability::Unstable,
+                                             "rustc_attrs",
+                                             "the `#[rustc_serialize_exclude_null]` attribute \
+                                              is an internal-only feature",
+                                             cfg_fn!(rustc_attrs))),
     ("rustc_synthetic", Whitelisted, Gated(Stability::Unstable,
                                                       "rustc_attrs",
                                                       "this attribute \
diff --git a/src/libsyntax/json.rs b/src/libsyntax/json.rs
index 7a8717ada4c..681e14a6137 100644
--- a/src/libsyntax/json.rs
+++ b/src/libsyntax/json.rs
@@ -108,6 +108,7 @@ struct Diagnostic {
 }
 
 #[derive(RustcEncodable)]
+#[allow(unused_attributes)]
 struct DiagnosticSpan {
     file_name: String,
     byte_start: u32,
@@ -129,6 +130,7 @@ struct DiagnosticSpan {
     /// that should be sliced in atop this span.
     suggested_replacement: Option<String>,
     /// If the suggestion is approximate
+    #[rustc_serialize_exclude_null]
     suggestion_approximate: Option<bool>,
     /// Macro invocations that created the code at this span, if any.
     expansion: Option<Box<DiagnosticSpanMacroExpansion>>,
diff --git a/src/libsyntax/lib.rs b/src/libsyntax/lib.rs
index 3b4c5da10f2..9181cca215c 100644
--- a/src/libsyntax/lib.rs
+++ b/src/libsyntax/lib.rs
@@ -25,6 +25,7 @@
 #![feature(match_default_bindings)]
 #![feature(i128_type)]
 #![feature(const_atomic_usize_new)]
+#![feature(rustc_attrs)]
 
 // See librustc_cratesio_shim/Cargo.toml for a comment explaining this.
 #[allow(unused_extern_crates)]
-- 
cgit 1.4.1-3-g733a5