Add missing docs

Author: GuillaumeGomez

stdsimd/arch/detect/error_macros.rs

@@ -2,6 +2,8 @@
 //! architecture. These macros provide a better error messages when the user
 //! attempts to call them in a different architecture.
 
+/// Prevents compilation if `is_x86_feature_detected` is used somewhere
+/// else than `x86` and `x86_64` targets.
 #[cfg(not(any(target_arch = "x86", target_arch = "x86_64")))]
 #[macro_export]
 #[unstable(feature = "stdsimd", issue = "27731")]
@@ -21,6 +23,8 @@ macro_rules! is_x86_feature_detected {
     };
 }
 
+/// Prevents compilation if `is_arm_feature_detected` is used somewhere else
+/// than `ARM` targets.
 #[cfg(not(target_arch = "arm"))]
 #[macro_export]
 #[unstable(feature = "stdsimd", issue = "27731")]
@@ -40,6 +44,8 @@ macro_rules! is_arm_feature_detected {
     };
 }
 
+/// Prevents compilation if `is_aarch64_feature_detected` is used somewhere else
+/// than `aarch64` targets.
 #[cfg(not(target_arch = "aarch64"))]
 #[macro_export]
 #[unstable(feature = "stdsimd", issue = "27731")]
@@ -59,6 +65,8 @@ macro_rules! is_aarch64_feature_detected {
     };
 }
 
+/// Prevents compilation if `is_powerpc_feature_detected` is used somewhere else
+/// than `PowerPC` targets.
 #[cfg(not(target_arch = "powerpc"))]
 #[macro_export]
 #[unstable(feature = "stdsimd", issue = "27731")]
@@ -78,6 +86,8 @@ guarding it behind a cfg(target_arch) as follows:
     };
 }
 
+/// Prevents compilation if `is_powerpc64_feature_detected` is used somewhere
+/// else than `PowerPC64` targets.
 #[cfg(not(target_arch = "powerpc64"))]
 #[macro_export]
 #[unstable(feature = "stdsimd", issue = "27731")]
@@ -97,6 +107,8 @@ guarding it behind a cfg(target_arch) as follows:
     };
 }
 
+/// Prevents compilation if `is_mips_feature_detected` is used somewhere else
+/// than `MIPS` targets.
 #[cfg(not(target_arch = "mips"))]
 #[macro_export]
 #[unstable(feature = "stdsimd", issue = "27731")]
@@ -116,6 +128,8 @@ macro_rules! is_mips_feature_detected {
     };
 }
 
+/// Prevents compilation if `is_mips64_feature_detected` is used somewhere else
+/// than `MIPS64` targets.
 #[cfg(not(target_arch = "mips64"))]
 #[macro_export]
 #[unstable(feature = "stdsimd", issue = "27731")]