@@ -256,6 +256,10 @@ So the stage2 compiler has to recompile `std` for the target.
256256
257257### Why does only libstd use ` cfg(bootstrap) ` ?
258258
259+ NOTE: for docs on ` cfg(bootstrap) ` itself, see [ Complications of Bootstrapping] [ complications ] .
260+ 261+ [ complications ] : #complications-of-bootstrapping
262+ 259263The ` rustc ` generated by the stage0 compiler is linked to the freshly-built
260264` std ` , which means that for the most part only ` std ` needs to be cfg-gated,
261265so that ` rustc ` can use features added to std immediately after their addition,
@@ -265,7 +269,7 @@ Note this is different from any other Rust program: stage1 `rustc`
265269is built by the _ beta_ compiler, but using the _ master_ version of libstd!
266270
267271The only time ` rustc ` uses ` cfg(bootstrap) ` is when it adds internal lints
268- that use diagnostic items. This happens very rarely .
272+ that use diagnostic items, or when it uses unstable library features that were recently changed .
269273
270274### What is a 'sysroot'?
271275
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