store the rustc version in metadata and check it

[arielb1]

This prevents ICEs when old crates are used with a new version of
rustc. Currently, the linking of crates compiled with different
versions of rustc is completely unsupported.

Fixes#28700

r? @nrc

[nrc]

@bors: r+

[bors]

📌 Commit debc1b9 has been approved by nrc

[nagisa]

Is rustc x.y enough? Maybe a version + commit would be better?

I'm pretty sure there’s a non-trivial population using nightly and these are not compatible between compiles either, are they?

[arielb1]

CFG_VERSION is what rustc --version outputs - for example, 1.4.0-nightly (8f1b0aa32 2015-08-21).

[bors]

⌛ Testing commit debc1b9 with merge 804326a...

[bors]

💔 Test failed - auto-linux-32-opt

[eefriedman]

../src/librustc/middle/expr_use_visitor.rs:283:9: 287:10 error: cannot infer an appropriate lifetime for lifetime parameter `'tcx` due to conflicting requirements
../src/librustc/middle/expr_use_visitor.rs:283 ExprUseVisitor {
../src/librustc/middle/expr_use_visitor.rs:284 typer: typer,
../src/librustc/middle/expr_use_visitor.rs:285 mc: mc::MemCategorizationContext::new(typer),
../src/librustc/middle/expr_use_visitor.rs:286 delegate: delegate,
../src/librustc/middle/expr_use_visitor.rs:287 }
../src/librustc/middle/expr_use_visitor.rs:279:5: 288:6 help: consider using an explicit lifetime parameter as shown: fn new(delegate: &'d mut Delegate<'tcx>, typer: &'t infer::InferCtxt<'a, 'a>)
-> ExprUseVisitor<'d, 't, 'a, 'a>
../src/librustc/middle/expr_use_visitor.rs:279 pub fn new(delegate: &'d mut Delegate<'tcx>,
../src/librustc/middle/expr_use_visitor.rs:280 typer: &'t infer::InferCtxt<'a, 'tcx>)
../src/librustc/middle/expr_use_visitor.rs:281 -> ExprUseVisitor<'d,'t,'a,'tcx>
../src/librustc/middle/expr_use_visitor.rs:282 {
../src/librustc/middle/expr_use_visitor.rs:283 ExprUseVisitor {
../src/librustc/middle/expr_use_visitor.rs:284 typer: typer,
...
error: aborting due to previous error

[arielb1]

@bors r=nrc 9699adc

[bors]

⌛ Testing commit 9699adc with merge ac17bcf...

[bors]

💔 Test failed - auto-win-msvc-32-opt

[arielb1]

This compiles locally. Why can't it compile on bors too?

[arielb1]

@bors r=nrc f2d5ebe

[nrc]

@arielb1 it's an intermittent bug, so annoying. Try adding let result = ...; result that sometimes works.

[bors]

⌛ Testing commit f2d5ebe with merge 65d5c08...

[bors]

☀️ Test successful - auto-linux-32-nopt-t, auto-linux-32-opt, auto-linux-64-nopt-t, auto-linux-64-opt, auto-linux-64-x-android-t, auto-mac-32-opt, auto-mac-64-nopt-t, auto-mac-64-opt, auto-win-gnu-32-nopt-t, auto-win-gnu-32-opt, auto-win-gnu-64-nopt-t, auto-win-gnu-64-opt, auto-win-msvc-32-opt, auto-win-msvc-64-opt