Avoid unnecessary (re-)allocations in the lexer
Avoid unnecessary heap allocations in the metadata ty decoder
tydecode: Accept a plain borrowed pointer to the data
Lexer: Avoid unnecessary allocations
TypeChecker: Avoid unnecessary copies
Remove some unnecessary closures
Avoid unnecessary allocations in the metadata decoder
Add a test that causes an ICE currently
rustc: Fix an ICE "Autoderef but type not derefable"

Related to #5062 (same error message), but that test case causes
a different ICE than mentioned there (even without this fix).
Add test for #5062
rustc::regionck: fix ICE when getting signature of ty_err

Fixes #5062
configure: replace echo "" with plain echo

When no arguments are given, echo prints a blank line.  These two are
equivalent:

  $ echo ""
  $ echo

Replace the former by the latter.

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
auto merge of #7015 : huonw/rust/each-fn-kill, r=thestinger

Continuation of #6995/#6999.
auto merge of #6970 : artagnon/rust/configure, r=catamorphism

When no arguments are given, echo prints a blank line.  These two are
equivalent:

  $ echo ""
  $ echo

Replace the former by the latter.

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
rm some uses of to_mut_unsafe_ptr
auto merge of #6992 : Blei/rust/fix-autoderef-ice, r=catamorphism

Related to #5062, but doesn't fix that one.
auto merge of #7004 : dotdash/rust/allocs, r=thestinger

This removes some unnecessary allocations in the lexer, the typechecker and the metadata decoder. Reduces the time spent in the parsing and typechecking passes by about 10% for me.
auto merge of #7016 : thestinger/rust/ptr, r=luqmana
fix decoding of multiple attributes (fixes #7017)

We were just looking at the last because we were overwriting ret.
add test for RcMut being Const and Owned, tests #7017 being fixed