Target-feature documented as unsafe. rustc book and rustc -C help have been modified.
diff --git a/src/librustc/session/config.rs b/src/librustc/session/config.rs
index 2446d4f..33b9dda 100644
--- a/src/librustc/session/config.rs
+++ b/src/librustc/session/config.rs
@@ -1149,7 +1149,8 @@
target_cpu: Option<String> = (None, parse_opt_string, [TRACKED],
"select target processor (`rustc --print target-cpus` for details)"),
target_feature: String = (String::new(), parse_string, [TRACKED],
- "target specific attributes (`rustc --print target-features` for details)"),
+ "target specific attributes. (`rustc --print target-features` for details). \
+ This feature is unsafe."),
passes: Vec<String> = (Vec::new(), parse_list, [TRACKED],
"a list of extra LLVM passes to run (space separated)"),
llvm_args: Vec<String> = (Vec::new(), parse_list, [TRACKED],
