Use question_mark feature in librustc_back.

src/librustc_back/target/aarch64_apple_ios.rs

@@ -12,7 +12,7 @@ use target::{Target, TargetOptions, TargetResult};
 use super::apple_ios_base::{opts, Arch};
 
 pub fn target() -> TargetResult {
-    let base = try!(opts(Arch::Arm64));
+    let base = opts(Arch::Arm64)?;
     Ok(Target {
         llvm_target: "arm64-apple-ios".to_string(),
         target_endian: "little".to_string(),

src/librustc_back/target/apple_ios_base.rs

@@ -68,7 +68,7 @@ fn build_pre_link_args(arch: Arch) -> Result<Vec<String>, String> {
 
     let arch_name = arch.to_string();
 
-    let sdk_root = try!(get_sdk_root(sdk_name));
+    let sdk_root = get_sdk_root(sdk_name)?;
 
     Ok(vec!["-arch".to_string(), arch_name.to_string(),
          "-Wl,-syslibroot".to_string(), sdk_root])
@@ -85,7 +85,7 @@ fn target_cpu(arch: Arch) -> String {
 }
 
 pub fn opts(arch: Arch) -> Result<TargetOptions, String> {
-    let pre_link_args = try!(build_pre_link_args(arch));
+    let pre_link_args = build_pre_link_args(arch)?;
     Ok(TargetOptions {
         cpu: target_cpu(arch),
         dynamic_linking: false,

src/librustc_back/target/armv7_apple_ios.rs

@@ -12,7 +12,7 @@ use target::{Target, TargetOptions, TargetResult};
 use super::apple_ios_base::{opts, Arch};
 
 pub fn target() -> TargetResult {
-    let base = try!(opts(Arch::Armv7));
+    let base = opts(Arch::Armv7)?;
     Ok(Target {
         llvm_target: "armv7-apple-ios".to_string(),
         target_endian: "little".to_string(),

src/librustc_back/target/armv7s_apple_ios.rs

@@ -12,7 +12,7 @@ use target::{Target, TargetOptions, TargetResult};
 use super::apple_ios_base::{opts, Arch};
 
 pub fn target() -> TargetResult {
-    let base = try!(opts(Arch::Armv7s));
+    let base = opts(Arch::Armv7s)?;
     Ok(Target {
         llvm_target: "armv7s-apple-ios".to_string(),
         target_endian: "little".to_string(),

src/librustc_back/target/i386_apple_ios.rs

@@ -12,7 +12,7 @@ use target::{Target, TargetOptions, TargetResult};
 use super::apple_ios_base::{opts, Arch};
 
 pub fn target() -> TargetResult {
-    let base = try!(opts(Arch::I386));
+    let base = opts(Arch::I386)?;
     Ok(Target {
         llvm_target: "i386-apple-ios".to_string(),
         target_endian: "little".to_string(),

src/librustc_back/target/i586_pc_windows_msvc.rs

@@ -11,7 +11,7 @@
 use target::TargetResult;
 
 pub fn target() -> TargetResult {
-    let mut base = try!(super::i686_pc_windows_msvc::target());
+    let mut base = super::i686_pc_windows_msvc::target()?;
     base.options.cpu = "pentium".to_string();
     base.llvm_target = "i586-pc-windows-msvc".to_string();
     Ok(base)

src/librustc_back/target/i586_unknown_linux_gnu.rs

@@ -11,7 +11,7 @@
 use target::TargetResult;
 
 pub fn target() -> TargetResult {
-    let mut base = try!(super::i686_unknown_linux_gnu::target());
+    let mut base = super::i686_unknown_linux_gnu::target()?;
     base.options.cpu = "pentium".to_string();
     base.llvm_target = "i586-unknown-linux-gnu".to_string();
     Ok(base)

src/librustc_back/target/mod.rs

@@ -77,12 +77,12 @@ macro_rules! supported_targets {
             match target {
                 $(
                     $triple => {
-                        let mut t = try!($module::target());
+                        let mut t = $module::target()?;
                         t.options.is_builtin = true;
 
                         // round-trip through the JSON parser to ensure at
                         // run-time that the parser works correctly
-                        t = try!(Target::from_json(t.to_json()));
+                        t = Target::from_json(t.to_json())?;
                         debug!("Got builtin target: {:?}", t);
                         Ok(t)
                     },
@@ -442,12 +442,12 @@ impl Target {
         };
 
         let mut base = Target {
-            llvm_target: try!(get_req_field("llvm-target")),
-            target_endian: try!(get_req_field("target-endian")),
-            target_pointer_width: try!(get_req_field("target-pointer-width")),
-            data_layout: try!(get_req_field("data-layout")),
-            arch: try!(get_req_field("arch")),
-            target_os: try!(get_req_field("os")),
+            llvm_target: get_req_field("llvm-target")?,
+            target_endian: get_req_field("target-endian")?,
+            target_pointer_width: get_req_field("target-pointer-width")?,
+            data_layout: get_req_field("data-layout")?,
+            arch: get_req_field("arch")?,
+            target_os: get_req_field("os")?,
             target_env: get_opt_field("env", ""),
             target_vendor: get_opt_field("vendor", "unknown"),
             options: Default::default(),

src/librustc_back/target/x86_64_apple_ios.rs

@@ -12,7 +12,7 @@ use target::{Target, TargetOptions, TargetResult};
 use super::apple_ios_base::{opts, Arch};
 
 pub fn target() -> TargetResult {
-    let base = try!(opts(Arch::X86_64));
+    let base = opts(Arch::X86_64)?;
     Ok(Target {
         llvm_target: "x86_64-apple-ios".to_string(),
         target_endian: "little".to_string(),