syntax: remove some dead code.
extra: %U support in time::strftime

Fixes #2350
syntax: indicate an error when a macro ignores trailing tokens.

That is, only a single expression or item gets parsed, so if there are
any extra tokens (e.g. the start of another item/expression) the user
should be told, rather than silently dropping them.

An example:

    macro_rules! foo {
        () => {
            println("hi");
            println("bye);
        }
    }

would expand to just `println("hi")`, which is almost certainly not
what the programmer wanted.

Fixes #8012.
auto merge of #9673 : huonw/rust/macros, r=catamorphism

That is, only a single expression or item gets parsed, so if there are
any extra tokens (e.g. the start of another item/expression) the user
should be told, rather than silently dropping them.

An example:

    macro_rules! foo {
        () => {
            println("hi");
            println("bye);
        }
    }

would expand to just `println("hi")`, which is almost certainly not
what the programmer wanted.

Fixes #8012.
De-pub resolve.rs
avoid alloca in with_overflow intrinsics

This is pointless, since it's just used to load an `undef` value and
never touched again.
auto merge of #9679 : pnkfelix/rust/de-pub-resolve-code, r=huonw

r? anyone

For context (and the archaeological dig that @huonw did to see how this arose), see:
  https://botbot.me/mozilla/rust-internals/msg/6547222/
treat uninhabited enums as voidish
make small (<= size_of::<int>()) enums immediate

C-like enums are excluded from this for now, because the code paths
specific to them need to be changed.

    fn foo() -> Option<~int> { Some(~5) }

Before:

    ; Function Attrs: uwtable
    define void @_ZN3foo18hdec6e36682b87eeaf4v0.0E(%"enum.std::option::Option<~int>[#1]"* noalias nocapture sret, { i64, %tydesc*, i8*, i8*, i8 }* nocapture readnone) #0 {
    "function top level":
      %2 = tail call %"enum.std::libc::types::common::c95::c_void[#1]"* @"_ZN2rt11global_heap10malloc_raw17h56c543b77f9b78aY11v0.9$x2dpreE"({ i64, %tydesc*, i8*, i8*, i8 }* undef, i64 8)
      %3 = bitcast %"enum.std::libc::types::common::c95::c_void[#1]"* %2 to i64*
      store i64 5, i64* %3, align 8
      %4 = getelementptr inbounds %"enum.std::option::Option<~int>[#1]"* %0, i64 0, i32 0
      store i64* %3, i64** %4, align 8
      ret void
    }

After:

    ; Function Attrs: uwtable
    define %"enum.std::option::Option<~int>[#1]" @_ZN3foo18h2cbf6557a3143edah4v0.0E({ i64, %tydesc*, i8*, i8*, i8 }* nocapture readnone) #0 {
    "function top level":
      %1 = tail call %"enum.std::libc::types::common::c95::c_void[#1]"* @"_ZN2rt11global_heap10malloc_raw18hb1e9dd1beab35edau11v0.9$x2dpreE"({ i64, %tydesc*, i8*, i8*, i8 }* undef, i64 8)
      %2 = bitcast %"enum.std::libc::types::common::c95::c_void[#1]"* %1 to i64*
      store i64 5, i64* %2, align 8
      %oldret = insertvalue %"enum.std::option::Option<~int>[#1]" undef, i64* %2, 0
      ret %"enum.std::option::Option<~int>[#1]" %oldret
    }
auto merge of #9677 : thestinger/rust/immediate, r=huonw

C-like enums are excluded from this for now, because the code paths
specific to them need to be changed.

    fn foo() -> Option<~int> { Some(~5) }

Before:

    ; Function Attrs: uwtable
    define void @_ZN3foo18hdec6e36682b87eeaf4v0.0E(%"enum.std::option::Option<~int>[#1]"* noalias nocapture sret, { i64, %tydesc*, i8*, i8*, i8 }* nocapture readnone) #0 {
    "function top level":
      %2 = tail call %"enum.std::libc::types::common::c95::c_void[#1]"* @"_ZN2rt11global_heap10malloc_raw17h56c543b77f9b78aY11v0.9$x2dpreE"({ i64, %tydesc*, i8*, i8*, i8 }* undef, i64 8)
      %3 = bitcast %"enum.std::libc::types::common::c95::c_void[#1]"* %2 to i64*
      store i64 5, i64* %3, align 8
      %4 = getelementptr inbounds %"enum.std::option::Option<~int>[#1]"* %0, i64 0, i32 0
      store i64* %3, i64** %4, align 8
      ret void
    }

After:

    ; Function Attrs: uwtable
    define %"enum.std::option::Option<~int>[#1]" @_ZN3foo18h2cbf6557a3143edah4v0.0E({ i64, %tydesc*, i8*, i8*, i8 }* nocapture readnone) #0 {
    "function top level":
      %1 = tail call %"enum.std::libc::types::common::c95::c_void[#1]"* @"_ZN2rt11global_heap10malloc_raw18hb1e9dd1beab35edau11v0.9$x2dpreE"({ i64, %tydesc*, i8*, i8*, i8 }* undef, i64 8)
      %2 = bitcast %"enum.std::libc::types::common::c95::c_void[#1]"* %1 to i64*
      store i64 5, i64* %2, align 8
      %oldret = insertvalue %"enum.std::option::Option<~int>[#1]" undef, i64* %2, 0
      ret %"enum.std::option::Option<~int>[#1]" %oldret
    }
extra: %G, %g and %V support in time::strftime

Fixes #2350
Check enums in missing_doc lint

Closes #9671
auto merge of #9670 : luisbg/rust/strftime, r=alexcrichton
auto merge of #9680 : thestinger/rust/overflow, r=huonw

This is pointless, since it's just used to load an `undef` value and
never touched again.
auto merge of #9675 : sfackler/rust/lint, r=alexcrichton

Closes #9671