MinGW: move unwind linkage to libunwind

src/librustc_codegen_ssa/back/link.rs

@@ -1218,29 +1218,10 @@ fn add_user_defined_link_args(
 
 /// Add arbitrary "late link" args defined by the target spec.
 /// FIXME: Determine where exactly these args need to be inserted.
-fn add_late_link_args(
-    cmd: &mut dyn Linker,
-    sess: &Session,
-    flavor: LinkerFlavor,
-    crate_type: config::CrateType,
-    codegen_results: &CodegenResults,
-) {
+fn add_late_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
     if let Some(args) = sess.target.target.options.late_link_args.get(&flavor) {
         cmd.args(args);
     }
-    let any_dynamic_crate = crate_type == config::CrateType::Dylib
-        || codegen_results.crate_info.dependency_formats.iter().any(|(ty, list)| {
-            *ty == crate_type && list.iter().any(|&linkage| linkage == Linkage::Dynamic)
-        });
-    if any_dynamic_crate {
-        if let Some(args) = sess.target.target.options.late_link_args_dynamic.get(&flavor) {
-            cmd.args(args);
-        }
-    } else {
-        if let Some(args) = sess.target.target.options.late_link_args_static.get(&flavor) {
-            cmd.args(args);
-        }
-    }
 }
 
 /// Add arbitrary "post-link" args defined by the target spec.
@@ -1581,7 +1562,7 @@ fn linker_with_args<'a, B: ArchiveBuilder<'a>>(
     cmd.finalize();
 
     // NO-OPT-OUT, OBJECT-FILES-MAYBE, CUSTOMIZATION-POINT
-    add_late_link_args(cmd, sess, flavor, crate_type, codegen_results);
+    add_late_link_args(cmd, sess, flavor);
 
     // NO-OPT-OUT, OBJECT-FILES-YES
     add_post_link_objects(cmd, sess, crate_type);

src/librustc_target/spec/mod.rs

@@ -581,12 +581,6 @@ pub struct TargetOptions {
     /// user-defined but before post_link_objects. Standard platform
     /// libraries that should be always be linked to, usually go here.
     pub late_link_args: LinkArgs,
-    /// Linker arguments used in addition to `late_link_args` if at least one
-    /// Rust dependency is dynamically linked.
-    pub late_link_args_dynamic: LinkArgs,
-    /// Linker arguments used in addition to `late_link_args` if aall Rust
-    /// dependencies are statically linked.
-    pub late_link_args_static: LinkArgs,
     /// Objects to link after all others, always found within the
     /// sysroot folder.
     pub post_link_objects: Vec<String>, // ... unconditionally
@@ -858,8 +852,6 @@ impl Default for TargetOptions {
             post_link_objects: Vec::new(),
             post_link_objects_crt: Vec::new(),
             late_link_args: LinkArgs::new(),
-            late_link_args_dynamic: LinkArgs::new(),
-            late_link_args_static: LinkArgs::new(),
             link_env: Vec::new(),
             link_env_remove: Vec::new(),
             archive_format: "gnu".to_string(),
@@ -1136,8 +1128,6 @@ impl Target {
         key!(pre_link_objects_exe_crt, list);
         key!(pre_link_objects_dll, list);
         key!(late_link_args, link_args);
-        key!(late_link_args_dynamic, link_args);
-        key!(late_link_args_static, link_args);
         key!(post_link_objects, list);
         key!(post_link_objects_crt, list);
         key!(post_link_args, link_args);
@@ -1363,8 +1353,6 @@ impl ToJson for Target {
         target_option_val!(pre_link_objects_exe_crt);
         target_option_val!(pre_link_objects_dll);
         target_option_val!(link_args - late_link_args);
-        target_option_val!(link_args - late_link_args_dynamic);
-        target_option_val!(link_args - late_link_args_static);
         target_option_val!(post_link_objects);
         target_option_val!(post_link_objects_crt);
         target_option_val!(link_args - post_link_args);

src/librustc_target/spec/windows_base.rs

@@ -17,13 +17,12 @@ pub fn opts() -> TargetOptions {
     );
 
     let mut late_link_args = LinkArgs::new();
-    let mut late_link_args_dynamic = LinkArgs::new();
-    let mut late_link_args_static = LinkArgs::new();
     late_link_args.insert(
         LinkerFlavor::Gcc,
         vec![
             "-lmingwex".to_string(),
             "-lmingw32".to_string(),
+            "-lgcc".to_string(),
             "-lmsvcrt".to_string(),
             // mingw's msvcrt is a weird hybrid import library and static library.
             // And it seems that the linker fails to use import symbols from msvcrt
@@ -38,33 +37,6 @@ pub fn opts() -> TargetOptions {
             "-lkernel32".to_string(),
         ],
     );
-    late_link_args_dynamic.insert(
-        LinkerFlavor::Gcc,
-        vec![
-            // If any of our crates are dynamically linked then we need to use
-            // the shared libgcc_s-dw2-1.dll. This is required to support
-            // unwinding across DLL boundaries.
-            "-lgcc_s".to_string(),
-            "-lgcc".to_string(),
-            "-lkernel32".to_string(),
-        ],
-    );
-    late_link_args_static.insert(
-        LinkerFlavor::Gcc,
-        vec![
-            // If all of our crates are statically linked then we can get away
-            // with statically linking the libgcc unwinding code. This allows
-            // binaries to be redistributed without the libgcc_s-dw2-1.dll
-            // dependency, but unfortunately break unwinding across DLL
-            // boundaries when unwinding across FFI boundaries.
-            "-lgcc".to_string(),
-            "-lgcc_eh".to_string(),
-            "-lpthread".to_string(),
-            // libpthread depends on libmsvcrt, so we need to link it *again*.
-            "-lmsvcrt".to_string(),
-            "-lkernel32".to_string(),
-        ],
-    );
 
     TargetOptions {
         // FIXME(#13846) this should be enabled for windows
@@ -90,8 +62,6 @@ pub fn opts() -> TargetOptions {
             "rsbegin.o".to_string(),
         ],
         late_link_args,
-        late_link_args_dynamic,
-        late_link_args_static,
         post_link_objects: vec!["rsend.o".to_string()],
         abi_return_struct_as_int: true,
         emit_debug_gdb_scripts: false,

src/libunwind/build.rs

@@ -33,7 +33,7 @@ fn main() {
     } else if target.contains("dragonfly") {
         println!("cargo:rustc-link-lib=gcc_pic");
     } else if target.contains("pc-windows-gnu") {
-        // This is handled in the target spec with late_link_args_[static|dynamic]
+        // This is handled in lib.rs
 
         // cfg!(bootstrap) doesn't work in build scripts
         if env::var("RUSTC_STAGE").ok() == Some("0".to_string()) {

src/libunwind/lib.rs

@@ -27,3 +27,19 @@ extern "C" {}
 #[link(name = "gcc_eh", kind = "static-nobundle", cfg(target_feature = "crt-static"))]
 #[link(name = "gcc_s", cfg(not(target_feature = "crt-static")))]
 extern "C" {}
+
+// If any of our crates are dynamically linked then we need to use
+// the shared libgcc_s-dw2-1.dll. This is required to support
+// unwinding across DLL boundaries.
+// If all of our crates are statically linked then we can get away
+// with statically linking the libgcc unwinding code. This allows
+// binaries to be redistributed without the libgcc_s-dw2-1.dll
+// dependency, but unfortunately break unwinding across DLL
+// boundaries when unwinding across FFI boundaries.
+//
+// Linking order matters a lot here!
+#[cfg(all(not(bootstrap), target_os = "windows", target_env = "gnu", target_vendor = "pc"))]
+#[link(name = "gcc_eh", kind = "static-nobundle")]
+#[link(name = "pthread", kind = "static-nobundle")]
+#[link(name = "gcc_s")]
+extern "C" {}

src/test/run-make-fulldeps/windows-binary-no-external-deps/Makefile

@@ -0,0 +1,9 @@
+-include ../tools.mk
+
+# only-windows
+
+PATH=$(SYSTEMROOT)/system32
+
+all:
+	$(RUSTC) hello.rs
+	$(TMPDIR)/hello.exe

src/test/run-make-fulldeps/windows-binary-no-external-deps/hello.rs

@@ -0,0 +1,3 @@
+fn main() {
+    println!("Hello World!");
+}