librustc_back: convert fn target() to return Result

Change all the target generation functions to return a Result<Target,
String> so that targets that are unable to be instantiated can be
expressed as an Err instead of a panic!(). This should improve #33497 as
well.

Author: cardoe

src/librustc_back/target/aarch64_apple_ios.rs

@@ -8,11 +8,12 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use target::{Target, TargetOptions};
+use target::{Target, TargetOptions, TargetResult};
 use super::apple_ios_base::{opts, Arch};
 
-pub fn target() -> Target {
-    Target {
+pub fn target() -> TargetResult {
+    let base = try!(opts(Arch::Arm64));
+    Ok(Target {
         llvm_target: "arm64-apple-ios".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "64".to_string(),
@@ -25,7 +26,7 @@ pub fn target() -> Target {
             features: "+neon,+fp-armv8,+cyclone".to_string(),
             eliminate_frame_pointer: false,
             max_atomic_width: 128,
-            .. opts(Arch::Arm64)
+            .. base
         },
-    }
+    })
 }

src/librustc_back/target/aarch64_linux_android.rs

@@ -8,15 +8,15 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use target::Target;
+use target::{Target, TargetResult};
 
-pub fn target() -> Target {
+pub fn target() -> TargetResult {
     let mut base = super::android_base::opts();
     base.max_atomic_width = 128;
     // As documented in http://developer.android.com/ndk/guides/cpu-features.html
     // the neon (ASIMD) and FP must exist on all android aarch64 targets.
     base.features = "+neon,+fp-armv8".to_string();
-    Target {
+    Ok(Target {
         llvm_target: "aarch64-linux-android".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "64".to_string(),
@@ -26,5 +26,5 @@ pub fn target() -> Target {
         target_env: "".to_string(),
         target_vendor: "unknown".to_string(),
         options: base,
-    }
+    })
 }

src/librustc_back/target/aarch64_unknown_linux_gnu.rs

@@ -8,12 +8,12 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use target::Target;
+use target::{Target, TargetResult};
 
-pub fn target() -> Target {
+pub fn target() -> TargetResult {
     let mut base = super::linux_base::opts();
     base.max_atomic_width = 128;
-    Target {
+    Ok(Target {
         llvm_target: "aarch64-unknown-linux-gnu".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "64".to_string(),
@@ -23,5 +23,5 @@ pub fn target() -> Target {
         target_os: "linux".to_string(),
         target_vendor: "unknown".to_string(),
         options: base,
-    }
+    })
 }

src/librustc_back/target/apple_ios_base.rs

@@ -36,7 +36,7 @@ impl Arch {
     }
 }
 
-pub fn get_sdk_root(sdk_name: &str) -> String {
+pub fn get_sdk_root(sdk_name: &str) -> Result<String, String> {
     let res = Command::new("xcrun")
                       .arg("--show-sdk-path")
                       .arg("-sdk")
@@ -55,21 +55,23 @@ pub fn get_sdk_root(sdk_name: &str) -> String {
                       });
 
     match res {
-        Ok(output) => output.trim().to_string(),
-        Err(e) => panic!("failed to get {} SDK path: {}", sdk_name, e)
+        Ok(output) => Ok(output.trim().to_string()),
+        Err(e) => Err(format!("failed to get {} SDK path: {}", sdk_name, e))
     }
 }
 
-fn pre_link_args(arch: Arch) -> Vec<String> {
+fn build_pre_link_args(arch: Arch) -> Result<Vec<String>, String> {
     let sdk_name = match arch {
         Armv7 | Armv7s | Arm64 => "iphoneos",
         I386 | X86_64 => "iphonesimulator"
     };
 
     let arch_name = arch.to_string();
 
-    vec!["-arch".to_string(), arch_name.to_string(),
-         "-Wl,-syslibroot".to_string(), get_sdk_root(sdk_name)]
+    let sdk_root = try!(get_sdk_root(sdk_name));
+
+    Ok(vec!["-arch".to_string(), arch_name.to_string(),
+         "-Wl,-syslibroot".to_string(), sdk_root])
 }
 
 fn target_cpu(arch: Arch) -> String {
@@ -82,13 +84,14 @@ fn target_cpu(arch: Arch) -> String {
     }.to_string()
 }
 
-pub fn opts(arch: Arch) -> TargetOptions {
-    TargetOptions {
+pub fn opts(arch: Arch) -> Result<TargetOptions, String> {
+    let pre_link_args = try!(build_pre_link_args(arch));
+    Ok(TargetOptions {
         cpu: target_cpu(arch),
         dynamic_linking: false,
         executables: true,
-        pre_link_args: pre_link_args(arch),
+        pre_link_args: pre_link_args,
         has_elf_tls: false,
         .. super::apple_base::opts()
-    }
+    })
 }

src/librustc_back/target/arm_linux_androideabi.rs

@@ -8,14 +8,14 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use target::Target;
+use target::{Target, TargetResult};
 
-pub fn target() -> Target {
+pub fn target() -> TargetResult {
     let mut base = super::android_base::opts();
     base.features = "+v7,+vfp3,+d16".to_string();
     base.max_atomic_width = 64;
 
-    Target {
+    Ok(Target {
         llvm_target: "arm-linux-androideabi".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "32".to_string(),
@@ -25,5 +25,5 @@ pub fn target() -> Target {
         target_env: "".to_string(),
         target_vendor: "unknown".to_string(),
         options: base,
-    }
+    })
 }

src/librustc_back/target/arm_unknown_linux_gnueabi.rs

@@ -8,12 +8,12 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use target::{Target, TargetOptions};
+use target::{Target, TargetOptions, TargetResult};
 
-pub fn target() -> Target {
+pub fn target() -> TargetResult {
     let mut base = super::linux_base::opts();
     base.max_atomic_width = 64;
-    Target {
+    Ok(Target {
         llvm_target: "arm-unknown-linux-gnueabi".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "32".to_string(),
@@ -27,5 +27,5 @@ pub fn target() -> Target {
             features: "+v6".to_string(),
             .. base
         },
-    }
+    })
 }

src/librustc_back/target/arm_unknown_linux_gnueabihf.rs

@@ -8,12 +8,12 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use target::{Target, TargetOptions};
+use target::{Target, TargetOptions, TargetResult};
 
-pub fn target() -> Target {
+pub fn target() -> TargetResult {
     let mut base = super::linux_base::opts();
     base.max_atomic_width = 64;
-    Target {
+    Ok(Target {
         llvm_target: "arm-unknown-linux-gnueabihf".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "32".to_string(),
@@ -27,5 +27,5 @@ pub fn target() -> Target {
             features: "+v6,+vfp2".to_string(),
             .. base
         }
-    }
+    })
 }

src/librustc_back/target/armv7_apple_ios.rs

@@ -8,11 +8,12 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use target::{Target, TargetOptions};
+use target::{Target, TargetOptions, TargetResult};
 use super::apple_ios_base::{opts, Arch};
 
-pub fn target() -> Target {
-    Target {
+pub fn target() -> TargetResult {
+    let base = try!(opts(Arch::Armv7));
+    Ok(Target {
         llvm_target: "armv7-apple-ios".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "32".to_string(),
@@ -24,7 +25,7 @@ pub fn target() -> Target {
         options: TargetOptions {
             features: "+v7,+vfp3,+neon".to_string(),
             max_atomic_width: 64,
-            .. opts(Arch::Armv7)
+            .. base
         }
-    }
+    })
 }

src/librustc_back/target/armv7_linux_androideabi.rs

@@ -8,14 +8,14 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use target::Target;
+use target::{Target, TargetResult};
 
-pub fn target() -> Target {
+pub fn target() -> TargetResult {
     let mut base = super::android_base::opts();
     base.features = "+v7,+thumb2,+vfp3,+d16".to_string();
     base.max_atomic_width = 64;
 
-    Target {
+    Ok(Target {
         llvm_target: "armv7-none-linux-android".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "32".to_string(),
@@ -25,5 +25,5 @@ pub fn target() -> Target {
         target_env: "".to_string(),
         target_vendor: "unknown".to_string(),
         options: base,
-    }
+    })
 }

src/librustc_back/target/armv7_unknown_linux_gnueabihf.rs

@@ -8,11 +8,11 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use target::{Target, TargetOptions};
+use target::{Target, TargetOptions, TargetResult};
 
-pub fn target() -> Target {
+pub fn target() -> TargetResult {
     let base = super::linux_base::opts();
-    Target {
+    Ok(Target {
         llvm_target: "armv7-unknown-linux-gnueabihf".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "32".to_string(),
@@ -28,6 +28,6 @@ pub fn target() -> Target {
             max_atomic_width: 64,
             .. base
         }
-    }
+    })
 }
 

src/librustc_back/target/armv7s_apple_ios.rs

@@ -8,11 +8,12 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use target::{Target, TargetOptions};
+use target::{Target, TargetOptions, TargetResult};
 use super::apple_ios_base::{opts, Arch};
 
-pub fn target() -> Target {
-    Target {
+pub fn target() -> TargetResult {
+    let base = try!(opts(Arch::Armv7s));
+    Ok(Target {
         llvm_target: "armv7s-apple-ios".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "32".to_string(),
@@ -24,7 +25,7 @@ pub fn target() -> Target {
         options: TargetOptions {
             features: "+v7,+vfp4,+neon".to_string(),
             max_atomic_width: 64,
-            .. opts(Arch::Armv7s)
+            .. base
         }
-    }
+    })
 }

src/librustc_back/target/asmjs_unknown_emscripten.rs

@@ -10,7 +10,7 @@
 
 use super::{Target, TargetOptions};
 
-pub fn target() -> Target {
+pub fn target() -> Result<Target, String> {
     let opts = TargetOptions {
         linker: "emcc".to_string(),
         ar: "emar".to_string(),
@@ -25,7 +25,7 @@ pub fn target() -> Target {
         max_atomic_width: 32,
         .. Default::default()
     };
-    Target {
+    Ok(Target {
         llvm_target: "asmjs-unknown-emscripten".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "32".to_string(),
@@ -35,5 +35,5 @@ pub fn target() -> Target {
         data_layout: "e-p:32:32-i64:64-v128:32:128-n32-S128".to_string(),
         arch: "asmjs".to_string(),
         options: opts,
-    }
+    })
 }

src/librustc_back/target/i386_apple_ios.rs

@@ -8,11 +8,12 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use target::{Target, TargetOptions};
+use target::{Target, TargetOptions, TargetResult};
 use super::apple_ios_base::{opts, Arch};
 
-pub fn target() -> Target {
-    Target {
+pub fn target() -> TargetResult {
+    let base = try!(opts(Arch::I386));
+    Ok(Target {
         llvm_target: "i386-apple-ios".to_string(),
         target_endian: "little".to_string(),
         target_pointer_width: "32".to_string(),
@@ -23,7 +24,7 @@ pub fn target() -> Target {
         target_vendor: "apple".to_string(),
         options: TargetOptions {
             max_atomic_width: 64,
-            .. opts(Arch::I386)
+            .. base
         }
-    }
+    })
 }

src/librustc_back/target/i586_pc_windows_msvc.rs

@@ -8,11 +8,11 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use target::Target;
+use target::TargetResult;
 
-pub fn target() -> Target {
-    let mut base = super::i686_pc_windows_msvc::target();
+pub fn target() -> TargetResult {
+    let mut base = try!(super::i686_pc_windows_msvc::target());
     base.options.cpu = "pentium".to_string();
     base.llvm_target = "i586-pc-windows-msvc".to_string();
-    return base
+    Ok(base)
 }

src/librustc_back/target/i586_unknown_linux_gnu.rs

@@ -8,11 +8,11 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use target::Target;
+use target::TargetResult;
 
-pub fn target() -> Target {
-    let mut base = super::i686_unknown_linux_gnu::target();
+pub fn target() -> TargetResult {
+    let mut base = try!(super::i686_unknown_linux_gnu::target());
     base.options.cpu = "pentium".to_string();
     base.llvm_target = "i586-unknown-linux-gnu".to_string();
-    return base
+    Ok(base)
 }