Apply c_enum_min_bits = 8 to (arm|thumb)-none- platforms

Author: Manishearth

compiler/rustc_target/src/spec/armebv7r_none_eabi.rs

@@ -20,6 +20,8 @@ pub fn target() -> Target {
             panic_strategy: PanicStrategy::Abort,
             max_atomic_width: Some(32),
             emit_debug_gdb_scripts: false,
+            // GCC and Clang default to 8 for arm-none here
+            c_enum_min_bits: 8,
             ..Default::default()
         },
     }

compiler/rustc_target/src/spec/armebv7r_none_eabihf.rs

@@ -21,6 +21,8 @@ pub fn target() -> Target {
             features: "+vfp3,-d32,-fp16".to_string(),
             max_atomic_width: Some(32),
             emit_debug_gdb_scripts: false,
+            // GCC and Clang default to 8 for arm-none here
+            c_enum_min_bits: 8,
             ..Default::default()
         },
     }

compiler/rustc_target/src/spec/armv7a_none_eabi.rs

@@ -28,6 +28,7 @@ pub fn target() -> Target {
         max_atomic_width: Some(64),
         panic_strategy: PanicStrategy::Abort,
         emit_debug_gdb_scripts: false,
+        c_enum_min_bits: 8,
         ..Default::default()
     };
     Target {

compiler/rustc_target/src/spec/armv7a_none_eabihf.rs

@@ -19,6 +19,8 @@ pub fn target() -> Target {
         max_atomic_width: Some(64),
         panic_strategy: PanicStrategy::Abort,
         emit_debug_gdb_scripts: false,
+        // GCC and Clang default to 8 for arm-none here
+        c_enum_min_bits: 8,
         ..Default::default()
     };
     Target {

compiler/rustc_target/src/spec/armv7r_none_eabi.rs

@@ -19,6 +19,8 @@ pub fn target() -> Target {
             panic_strategy: PanicStrategy::Abort,
             max_atomic_width: Some(32),
             emit_debug_gdb_scripts: false,
+            // GCC and Clang default to 8 for arm-none here
+            c_enum_min_bits: 8,
             ..Default::default()
         },
     }

compiler/rustc_target/src/spec/armv7r_none_eabihf.rs

@@ -20,6 +20,8 @@ pub fn target() -> Target {
             features: "+vfp3,-d32,-fp16".to_string(),
             max_atomic_width: Some(32),
             emit_debug_gdb_scripts: false,
+            // GCC and Clang default to 8 for arm-none here
+            c_enum_min_bits: 8,
             ..Default::default()
         },
     }

compiler/rustc_target/src/spec/thumb_base.rs

@@ -53,6 +53,9 @@ pub fn opts() -> TargetOptions {
         // LLVM is eager to trash the link register when calling `noreturn` functions, which
         // breaks debugging. Preserve LR by default to prevent that from happening.
         frame_pointer: FramePointer::Always,
+        // ARM supports multiple ABIs for enums, the linux one matches the default of 32 here
+        // but any arm-none or thumb-none target will be defaulted to 8 on GCC and clang
+        c_enum_min_bits: 8,
         ..Default::default()
     }
 }