Use serde for target spec json deserialize

Cargo.lock

@@ -4499,7 +4499,10 @@ dependencies = [
  "rustc_macros",
  "rustc_serialize",
  "rustc_span",
+ "serde",
+ "serde_derive",
  "serde_json",
+ "serde_path_to_error",
  "tracing",
 ]
 
@@ -4870,6 +4873,16 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "serde_path_to_error"
+version = "0.1.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "59fab13f937fa393d08645bf3a84bdfe86e296747b506ada67bb15f10f218b2a"
+dependencies = [
+ "itoa",
+ "serde",
+]
+
 [[package]]
 name = "serde_spanned"
 version = "0.6.9"

compiler/rustc_session/src/config.rs

@@ -336,12 +336,12 @@ impl LinkSelfContained {
         if let Some(component_to_enable) = component.strip_prefix('+') {
             self.explicitly_set = None;
             self.enabled_components
-                .insert(LinkSelfContainedComponents::from_str(component_to_enable)?);
+                .insert(LinkSelfContainedComponents::from_str(component_to_enable).ok()?);
             Some(())
         } else if let Some(component_to_disable) = component.strip_prefix('-') {
             self.explicitly_set = None;
             self.disabled_components
-                .insert(LinkSelfContainedComponents::from_str(component_to_disable)?);
+                .insert(LinkSelfContainedComponents::from_str(component_to_disable).ok()?);
             Some(())
         } else {
             None

compiler/rustc_session/src/options.rs

@@ -1295,7 +1295,7 @@ pub mod parse {
     }
 
     pub(crate) fn parse_linker_flavor(slot: &mut Option<LinkerFlavorCli>, v: Option<&str>) -> bool {
-        match v.and_then(LinkerFlavorCli::from_str) {
+        match v.and_then(|v| LinkerFlavorCli::from_str(v).ok()) {
             Some(lf) => *slot = Some(lf),
             _ => return false,
         }

compiler/rustc_target/Cargo.toml

@@ -12,7 +12,10 @@ rustc_fs_util = { path = "../rustc_fs_util" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_serialize = { path = "../rustc_serialize" }
 rustc_span = { path = "../rustc_span" }
+serde = "1.0.219"
+serde_derive = "1.0.219"
 serde_json = "1.0.59"
+serde_path_to_error = "0.1.17"
 tracing = "0.1"
 # tidy-alphabetical-end
 

compiler/rustc_target/src/json.rs

@@ -114,3 +114,18 @@ impl ToJson for rustc_abi::CanonAbi {
         self.to_string().to_json()
     }
 }
+
+macro_rules! serde_deserialize_from_str {
+    ($ty:ty) => {
+        impl<'de> serde::Deserialize<'de> for $ty {
+            fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+            where
+                D: serde::Deserializer<'de>,
+            {
+                let s = String::deserialize(deserializer)?;
+                FromStr::from_str(&s).map_err(serde::de::Error::custom)
+            }
+        }
+    };
+}
+pub(crate) use serde_deserialize_from_str;