windows-gnullvm: always link libunwind statically

compiler/rustc_target/src/spec/base/windows_gnullvm.rs

@@ -13,13 +13,14 @@ pub(crate) fn opts() -> TargetOptions {
     // but LLVM maintainers rejected it: https://reviews.llvm.org/D51440
     let pre_link_args = TargetOptions::link_args(
         LinkerFlavor::Gnu(Cc::Yes, Lld::No),
-        &["-nolibc", "--unwindlib=none"],
+        &["-nolibc", "--unwindlib=libunwind", "-static-libgcc"],
     );
     // Order of `late_link_args*` does not matter with LLD.
     let mingw_libs = &["-lmingw32", "-lmingwex", "-lmsvcrt", "-lkernel32", "-luser32"];
 
     let mut late_link_args =
         TargetOptions::link_args(LinkerFlavor::Gnu(Cc::No, Lld::No), mingw_libs);
+    add_link_args(&mut late_link_args, LinkerFlavor::Gnu(Cc::No, Lld::No), &["-l:libunwind.a"]);
     add_link_args(&mut late_link_args, LinkerFlavor::Gnu(Cc::Yes, Lld::No), mingw_libs);
 
     TargetOptions {
@@ -46,8 +47,6 @@ pub(crate) fn opts() -> TargetOptions {
         eh_frame_header: false,
         no_default_libraries: false,
         has_thread_local: true,
-        crt_static_allows_dylibs: true,
-        crt_static_respected: true,
         debuginfo_kind: DebuginfoKind::Dwarf,
         // FIXME(davidtwco): Support Split DWARF on Windows GNU - may require LLVM changes to
         // output DWO, despite using DWARF, doesn't use ELF..

library/unwind/src/lib.rs

@@ -214,8 +214,3 @@ cfg_select! {
 #[cfg(target_os = "hurd")]
 #[link(name = "gcc_s")]
 unsafe extern "C" {}
-
-#[cfg(all(target_os = "windows", target_env = "gnu", target_abi = "llvm"))]
-#[link(name = "unwind", kind = "static", modifiers = "-bundle", cfg(target_feature = "crt-static"))]
-#[link(name = "unwind", cfg(not(target_feature = "crt-static")))]
-unsafe extern "C" {}

src/bootstrap/src/core/build_steps/dist.rs

@@ -323,7 +323,6 @@ fn make_win_llvm_dist(plat_root: &Path, target: TargetSelection, builder: &Build
     let target_libs = [
         // MinGW libs
         "libunwind.a",
-        "libunwind.dll.a",
         "libmingw32.a",
         "libmingwex.a",
         "libmsvcrt.a",

src/doc/rustc/src/platform-support/windows-gnullvm.md

@@ -19,7 +19,7 @@ Target triples available so far:
 ## Requirements
 
 Building those targets requires an LLVM-based C toolchain, for example, [llvm-mingw][1] or [MSYS2][2] with CLANG*
-environment.
+environment, with static libunwind library available.
 
 Binaries for this target should be at least on par with `*-windows-gnu` in terms of requirements and functionality,
 except for implicit self-contained mode (explained in [the section below](#building-rust-programs)).