dev-lang/rust: fix segfaults with system llvm:7

Bug: https://bugs.gentoo.org/675752
Package-Manager: Portage-2.3.57, Repoman-2.3.12
Signed-off-by: Georgy Yakovlev <gyakovlev@gentoo.org>

1 files changed, 33 insertions, 0 deletions

diff --git a/dev-lang/rust/files/1.32.0-system-llvm-7-SIGSEGV.patch b/dev-lang/rust/files/1.32.0-system-llvm-7-SIGSEGV.patch
new file mode 100644
index 000000000000..afc2cabde4b5
--- /dev/null
+++ b/dev-lang/rust/files/1.32.0-system-llvm-7-SIGSEGV.patch
@@ -0,0 +1,33 @@
+From 1c95f5a34c14f08d65cdd198827e3a2fcb63cf39 Mon Sep 17 00:00:00 2001
+From: Tom Tromey <tom@tromey.com>
+Date: Tue, 22 Jan 2019 11:13:53 -0700
+Subject: [PATCH] Fix issue 57762
+
+Issue 57762 points out a compiler crash when the compiler was built
+using a stock LLVM 7.  LLVM 7 was released without a necessary fix for
+a bug in the DWARF discriminant code.
+
+This patch changes rustc to use the fallback mode on (non-Rust) LLVM 7.
+
+Closes #57762
+---
+ src/librustc_codegen_llvm/debuginfo/metadata.rs | 6 +++++-
+ 1 file changed, 5 insertions(+), 1 deletion(-)
+
+diff --git a/src/librustc_codegen_llvm/debuginfo/metadata.rs b/src/librustc_codegen_llvm/debuginfo/metadata.rs
+index 6deedd0b5ea3..a354eef6887a 100644
+--- a/src/librustc_codegen_llvm/debuginfo/metadata.rs
++++ b/src/librustc_codegen_llvm/debuginfo/metadata.rs
+@@ -1164,7 +1164,11 @@ fn use_enum_fallback(cx: &CodegenCx) -> bool {
+     // On MSVC we have to use the fallback mode, because LLVM doesn't
+     // lower variant parts to PDB.
+     return cx.sess().target.target.options.is_like_msvc
+-        || llvm_util::get_major_version() < 7;
++        || llvm_util::get_major_version() < 7
++        // LLVM version 7 did not release with an important bug fix;
++        // but the required patch is in the equivalent Rust LLVM.
++        // See https://github.com/rust-lang/rust/issues/57762.
++        || (llvm_util::get_major_version() == 7 && unsafe { !llvm::LLVMRustIsRustLLVM() });
+ }
+ 
+ // Describes the members of an enum value: An enum is described as a union of