Rollup merge of #65972 - braiins:vkr-arm-panicking, r=alexcrichton

Fix libunwind build: Define __LITTLE_ENDIAN__ for LE targets

If `__LITTLE_ENDIAN__` is missing, libunwind assumes big endian
and reads unwinding instructions wrong on ARM EHABI.

Fix #65765

Technical background in referenced bug.

I didn't run any automated tests, just built a simple panicking program using the fixed toolchain and panicking started to work. Tried with `catch_unwind()` and that seems to work now too. libunwind's log seems ok now, I can paste it if needed.
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Tyler Mandry 2019-11-01 11:20:21 -07:00 committed by GitHub
commit 05de0d7c9f
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@ -56,12 +56,18 @@ mod llvm_libunwind {
pub fn compile() {
let target_env = env::var("CARGO_CFG_TARGET_ENV").unwrap();
let target_vendor = env::var("CARGO_CFG_TARGET_VENDOR").unwrap();
let target_endian_little = env::var("CARGO_CFG_TARGET_ENDIAN").unwrap() != "big";
let cfg = &mut cc::Build::new();
cfg.cpp(true);
cfg.cpp_set_stdlib(None);
cfg.warnings(false);
// libunwind expects a __LITTLE_ENDIAN__ macro to be set for LE archs, cf. #65765
if target_endian_little {
cfg.define("__LITTLE_ENDIAN__", Some("1"));
}
if target_env == "msvc" {
// Don't pull in extra libraries on MSVC
cfg.flag("/Zl");