Attempt to fix backtrace tests on i686-msvc

Some fixes for i686-msvc and Windows have landed on the `backtrace`
crate but hadn't made their way here yet. Let's update that and see if
it passes CI.

Cargo.lock

@@ -97,18 +97,12 @@ dependencies = [
  "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
-[[package]]
-name = "autocfg"
-version = "0.1.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
 [[package]]
 name = "backtrace"
-version = "0.3.29"
+version = "0.3.34"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "autocfg 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
- "backtrace-sys 0.1.27 (registry+https://github.com/rust-lang/crates.io-index)",
+ "backtrace-sys 0.1.30 (registry+https://github.com/rust-lang/crates.io-index)",
  "cfg-if 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "compiler_builtins 0.1.18 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.54 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -118,7 +112,7 @@ dependencies = [
 
 [[package]]
 name = "backtrace-sys"
-version = "0.1.27"
+version = "0.1.30"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "cc 1.0.35 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -864,7 +858,7 @@ name = "error-chain"
 version = "0.12.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "backtrace 0.3.29 (registry+https://github.com/rust-lang/crates.io-index)",
+ "backtrace 0.3.34 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -879,7 +873,7 @@ name = "failure"
 version = "0.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "backtrace 0.3.29 (registry+https://github.com/rust-lang/crates.io-index)",
+ "backtrace 0.3.34 (registry+https://github.com/rust-lang/crates.io-index)",
  "failure_derive 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -2511,7 +2505,7 @@ name = "rustc"
 version = "0.0.0"
 dependencies = [
  "arena 0.0.0",
- "backtrace 0.3.29 (registry+https://github.com/rust-lang/crates.io-index)",
+ "backtrace 0.3.34 (registry+https://github.com/rust-lang/crates.io-index)",
  "bitflags 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "byteorder 1.2.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "chalk-engine 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -3457,7 +3451,7 @@ name = "std"
 version = "0.0.0"
 dependencies = [
  "alloc 0.0.0",
- "backtrace 0.3.29 (registry+https://github.com/rust-lang/crates.io-index)",
+ "backtrace 0.3.34 (registry+https://github.com/rust-lang/crates.io-index)",
  "cc 1.0.35 (registry+https://github.com/rust-lang/crates.io-index)",
  "cfg-if 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "compiler_builtins 0.1.18 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -4275,9 +4269,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum arrayref 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)" = "0d382e583f07208808f6b1249e60848879ba3543f57c32277bf52d69c2f0f0ee"
 "checksum arrayvec 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)" = "a1e964f9e24d588183fcb43503abda40d288c8657dfc27311516ce2f05675aef"
 "checksum atty 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)" = "9a7d5b8723950951411ee34d271d99dddcc2035a16ab25310ea2c8cfd4369652"
-"checksum autocfg 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)" = "0e49efa51329a5fd37e7c79db4621af617cd4e3e5bc224939808d076077077bf"
-"checksum backtrace 0.3.29 (registry+https://github.com/rust-lang/crates.io-index)" = "2d631cd7af21b7ff796293f1990104e3cdb606852863bac32f000c193aa35dfb"
-"checksum backtrace-sys 0.1.27 (registry+https://github.com/rust-lang/crates.io-index)" = "6ea90dd7b012b3d1a2cb6bec16670a0db2c95d4e931e84f4047e0460c1b34c8d"
+"checksum backtrace 0.3.34 (registry+https://github.com/rust-lang/crates.io-index)" = "b5164d292487f037ece34ec0de2fcede2faa162f085dd96d2385ab81b12765ba"
+"checksum backtrace-sys 0.1.30 (registry+https://github.com/rust-lang/crates.io-index)" = "5b3a000b9c543553af61bc01cbfc403b04b5caa9e421033866f2e98061eb3e61"
 "checksum base64 0.10.1 (registry+https://github.com/rust-lang/crates.io-index)" = "0b25d992356d2eb0ed82172f5248873db5560c4721f564b13cb5193bda5e668e"
 "checksum bitflags 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "3d155346769a6855b86399e9bc3814ab343cd3d62c7e985113d46a0ec3c281fd"
 "checksum blake2-rfc 0.2.18 (registry+https://github.com/rust-lang/crates.io-index)" = "5d6d530bdd2d52966a6d03b7a964add7ae1a288d25214066fd4b600f0f796400"

src/libstd/Cargo.toml

@@ -26,7 +26,7 @@ unwind = { path = "../libunwind" }
 hashbrown = { version = "0.4.0", features = ['rustc-dep-of-std'] }
 
 [dependencies.backtrace]
-version = "0.3.29"
+version = "0.3.34"
 default-features = false # don't use coresymbolication on OSX
 features = [
   "rustc-dep-of-std", # enable build support for integrating into libstd

src/test/ui/backtrace-debuginfo.rs

@@ -11,7 +11,6 @@
 // ignore-pretty issue #37195
 // ignore-cloudabi spawning processes is not supported
 // ignore-emscripten spawning processes is not supported
-// ignore-msvc issue #62844
 // ignore-sgx no processes
 // normalize-stderr-test ".*\n" -> ""
 
@@ -31,8 +30,23 @@ macro_rules! dump_and_die {
     ($($pos:expr),*) => ({
         // FIXME(#18285): we cannot include the current position because
         // the macro span takes over the last frame's file/line.
+        //
+        // You might also be wondering why a major platform,
+        // i686-pc-windows-msvc, is located in here. Some of the saga can be
+        // found on #62897, but the tl;dr; is that it appears that if the
+        // standard library doesn't have debug information or frame pointers,
+        // which it doesn't by default on the test builders, then the stack
+        // walking routines in dbghelp will randomly terminate the stack trace
+        // in libstd without going further. Presumably the addition of frame
+        // pointers and/or debuginfo fixes this since tests always work with
+        // nightly compilers (which have debuginfo). In general though this test
+        // is replicated in rust-lang/backtrace-rs and has extensive coverage
+        // there, even on i686-pc-windows-msvc. We do the best we can in
+        // rust-lang/rust to test it as well, but sometimes we just gotta keep
+        // landing PRs.
         if cfg!(any(target_os = "android",
                     all(target_os = "linux", target_arch = "arm"),
+                    all(target_env = "msvc", target_arch = "x86"),
                     target_os = "freebsd",
                     target_os = "dragonfly",
                     target_os = "openbsd")) {

src/test/ui/backtrace.rs

@@ -3,8 +3,8 @@
 // ignore-cloudabi spawning processes is not supported
 // ignore-emscripten spawning processes is not supported
 // ignore-openbsd no support for libbacktrace without filename
-// ignore-msvc issue #62844
 // ignore-sgx no processes
+// ignore-msvc see #62897 and `backtrace-debuginfo.rs` test
 // compile-flags:-g
 
 use std::env;