Include import name in import shadowing error messages.

This partially alleviates the confusing behavior in issue #16597
Update compile-fail tests due to changed diagnostics
Add compile-fail test for missing import shadowing case
doc: add missing word
doc: use the more convenient 'cargo run' command

This lovely command has already been introduced, so let's take advantage
of it.
doc: slight consistency fix

Others in this list are Capitalized, so do it here too.
Replace mention of ~T by Box<T> in the FFI guide.
Always insert methods into the search index, even if we're currently in a private module.

Previously, this caused methods of re-exported types to not be inserted into
the search index. This fix may introduce some false positives, but in my
testing they appear as orphaned methods and end up not being inserted into the
final search index at a later stage.

Fixes issue #11943
libcollections: In tests, remove some uses of deprecated methods and
unused imports.
add missing ! char to feature gate hint
Added a note for usage of abs with ::MIN.
Add a simple test for rustdoc search index contents
Fix sorting order. Change `sync` to `share`
debuginfo: Allow to activate GDB pretty printers in autotests.
debuginfo: Add GDB pretty printers for structs and enums.
debuginfo: Emit different autotest debugger scripts depending on GDB version.
debuginfo: Improve GDB version handling in compiletest tool
Allow *-pointers in PtrTy (fixes #16781)
Fix an ICE with error types in a vec

Closes #16783
Forbid ~str and ~[]

This corrects a rebasing error. Also adds a test so it won't happen again.