Add L4Bender as linker variant

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -1159,6 +1159,7 @@ pub fn linker_and_flavor(sess: &Session) -> (PathBuf, LinkerFlavor) {
                     LinkerFlavor::Lld(_) => "lld",
                     LinkerFlavor::PtxLinker => "rust-ptx-linker",
                     LinkerFlavor::BpfLinker => "bpf-linker",
+                    LinkerFlavor::L4Bender => "l4-bender",
                 }),
                 flavor,
             )),

compiler/rustc_codegen_ssa/src/back/linker.rs

@@ -3,6 +3,7 @@ use super::command::Command;
 use super::symbol_export;
 use rustc_span::symbol::sym;
 
+use std::env;
 use std::ffi::{OsStr, OsString};
 use std::fs::{self, File};
 use std::io::prelude::*;
@@ -126,7 +127,6 @@ pub fn get_linker<'a>(
     // FIXME: Move `/LIBPATH` addition for uwp targets from the linker construction
     // to the linker args construction.
     assert!(cmd.get_args().is_empty() || sess.target.vendor == "uwp");
-
     match flavor {
         LinkerFlavor::Lld(LldFlavor::Link) | LinkerFlavor::Msvc => {
             Box::new(MsvcLinker { cmd, sess }) as Box<dyn Linker>
@@ -149,6 +149,10 @@ pub fn get_linker<'a>(
         LinkerFlavor::PtxLinker => Box::new(PtxLinker { cmd, sess }) as Box<dyn Linker>,
 
         LinkerFlavor::BpfLinker => Box::new(BpfLinker { cmd, sess }) as Box<dyn Linker>,
+
+        LinkerFlavor::L4Bender => {
+                Box::new(L4Bender::new(cmd, sess)) as Box<dyn Linker>
+        },
     }
 }
 
@@ -1355,6 +1359,172 @@ impl<'a> Linker for WasmLd<'a> {
     }
 }
 
+/// Linker shepherd script for L4Re (Fiasco)
+pub struct L4Bender<'a> {
+    cmd: Command,
+    sess: &'a Session,
+    hinted_static: bool,
+}
+
+impl<'a> Linker for L4Bender<'a> {
+    fn link_dylib(&mut self, _lib: Symbol) {
+        panic!("dylibs not supported yet")
+    }
+    fn link_staticlib(&mut self, lib: Symbol) {
+        self.hint_static();
+        self.cmd.arg(format!("-PC{}", lib));
+    }
+    fn link_rlib(&mut self, lib: &Path) {
+        self.hint_static();
+        self.cmd.arg(lib);
+    }
+    fn include_path(&mut self, path: &Path) {
+        self.cmd.arg("-L").arg(path);
+    }
+    fn framework_path(&mut self, _: &Path) {
+        bug!("Frameworks are not supported on L4Re!");
+    }
+    fn output_filename(&mut self, path: &Path) { self.cmd.arg("-o").arg(path); }
+    fn add_object(&mut self, path: &Path) { self.cmd.arg(path); }
+    // not sure about pie on L4Re
+    fn position_independent_executable(&mut self) { }
+    fn no_position_independent_executable(&mut self) { }
+    fn full_relro(&mut self) { self.cmd.arg("-z,relro,-z,now"); }
+    fn partial_relro(&mut self) { self.cmd.arg("-z,relro"); }
+    fn no_relro(&mut self) { self.cmd.arg("-z,norelro"); }
+    fn build_static_executable(&mut self) { self.cmd.arg("-static"); }
+    fn cmd(&mut self) -> &mut Command {
+        &mut self.cmd
+    }
+
+    fn link_rust_dylib(&mut self, _: Symbol, _: &Path) {
+        panic!("Rust dylibs not supported");
+    }
+
+    fn link_framework(&mut self, _: Symbol) {
+        bug!("Frameworks not supported on L4Re.");
+    }
+
+    // Here we explicitly ask that the entire archive is included into the
+    // result artifact. For more details see #15460, but the gist is that
+    // the linker will strip away any unused objects in the archive if we
+    // don't otherwise explicitly reference them. This can occur for
+    // libraries which are just providing bindings, libraries with generic
+    // functions, etc.
+    fn link_whole_staticlib(&mut self, lib: Symbol, _: &[PathBuf]) {
+        self.hint_static();
+        self.cmd.arg("--whole-archive").arg(format!("-l{}", lib));
+        self.cmd.arg("--no-whole-archive");
+    }
+
+    fn link_whole_rlib(&mut self, lib: &Path) {
+        self.hint_static();
+        self.cmd.arg("--whole-archive").arg(lib).arg("--no-whole-archive");
+    }
+
+    fn gc_sections(&mut self, keep_metadata: bool) {
+        if !keep_metadata {
+            self.cmd.arg("--gc-sections");
+        }
+    }
+
+    fn optimize(&mut self) {
+        self.cmd.arg("-O2");
+    }
+
+    fn pgo_gen(&mut self) { }
+
+    fn debuginfo(&mut self, strip: Strip) {
+        match strip {
+            Strip::None => {}
+            Strip::Debuginfo => {
+                self.cmd().arg("--strip-debug"); }
+            Strip::Symbols => {
+                self.cmd().arg("--strip-all");
+            }
+        }
+    }
+
+    fn no_default_libraries(&mut self) {
+        self.cmd.arg("-nostdlib");
+    }
+
+    fn build_dylib(&mut self, _: &Path) {
+        bug!("not implemented");
+    }
+
+    fn export_symbols(&mut self, _: &Path, _: CrateType) {
+        // ToDo, not implemented, copy from GCC
+        return;
+    }
+
+    fn subsystem(&mut self, subsystem: &str) {
+        self.cmd.arg(&format!("--subsystem,{}", subsystem));
+    }
+
+    fn finalize(&mut self) {
+        self.hint_static(); // Reset to default before returning the composed command line.
+    }
+
+    fn group_start(&mut self) { self.cmd.arg("--start-group"); }
+    fn group_end(&mut self) { self.cmd.arg("--end-group"); }
+    fn linker_plugin_lto(&mut self) {
+        // do nothing
+    }
+    fn control_flow_guard(&mut self) {
+        self.sess.warn("Windows Control Flow Guard is not supported by this linker.");
+    }
+
+    fn no_crt_objects(&mut self) { }
+}
+
+impl<'a> L4Bender<'a> {
+    pub fn new(mut cmd: Command, sess: &'a Session) -> L4Bender<'a> {
+        if let Ok(l4bender_args) = env::var("L4_BENDER_ARGS") {
+            L4Bender::split_cmd_args(&mut cmd, &l4bender_args);
+        }
+
+        cmd.arg("--"); // separate direct l4-bender args from linker args
+
+        L4Bender {
+            cmd: cmd,
+            sess: sess,
+            hinted_static: false,
+        }
+    }
+
+    /// This parses a shell-escaped string and unquotes the arguments. It doesn't attempt to
+    /// completely understand shell, but should instead allow passing arguments like
+    /// `-Dlinker="ld -m x86_64"`, and a copy without quotes, but spaces preserved, is added as an
+    /// argument to the given Command. This means that constructs as \" are not understood, so
+    /// quote wisely.
+    fn split_cmd_args(cmd: &mut Command, shell_args: &str) {
+        let mut arg = String::new();
+        let mut quoted = false;
+        for character in shell_args.chars() {
+            match character {
+                ' ' if !quoted => {
+                    cmd.arg(&arg);
+                    arg.clear();
+                },
+                '"' | '\'' => quoted = !quoted,
+                _ => arg.push(character),
+            };
+        }
+        if arg.len() > 0 {
+            cmd.arg(&arg);
+            arg.clear();
+        }
+    }
+
+    fn hint_static(&mut self) {
+        if !self.hinted_static {
+            self.cmd.arg("-static");
+            self.hinted_static = true;
+        }
+    }
+}
+
 pub(crate) fn exported_symbols(tcx: TyCtxt<'_>, crate_type: CrateType) -> Vec<String> {
     if let Some(ref exports) = tcx.sess.target.override_export_symbols {
         return exports.clone();

compiler/rustc_target/src/spec/l4re_base.rs

@@ -1,16 +1,5 @@
-use crate::spec::{LinkerFlavor, PanicStrategy, TargetOptions};
-//use std::process::Command;
-
-// Use GCC to locate code for crt* libraries from the host, not from L4Re. Note
-// that a few files also come from L4Re, for these, the function shouldn't be
-// used. This uses GCC for the location of the file, but GCC is required for L4Re anyway.
-//fn get_path_or(filename: &str) -> String {
-//    let child = Command::new("gcc")
-//        .arg(format!("-print-file-name={}", filename)).output()
-//        .expect("Failed to execute GCC");
-//    String::from_utf8(child.stdout)
-//        .expect("Couldn't read path from GCC").trim().into()
-//}
+use crate::spec::{LinkArgs, LinkerFlavor, PanicStrategy, TargetOptions};
+use std::default::Default;
 
 pub fn opts() -> TargetOptions {
     TargetOptions {
@@ -19,9 +8,9 @@ pub fn opts() -> TargetOptions {
         linker_flavor: LinkerFlavor::Ld,
         executables: true,
         panic_strategy: PanicStrategy::Abort,
-        linker: Some("ld".to_string()),
-        linker_is_gnu: false,
-        families: vec!["unix".to_string()],
+        linker: Some("l4-bender".to_string()),
+        pre_link_args: args,
+        os_family: Some("unix".to_string()),
         ..Default::default()
     }
 }

compiler/rustc_target/src/spec/mod.rs

@@ -90,6 +90,7 @@ mod windows_uwp_msvc_base;
 pub enum LinkerFlavor {
     Em,
     Gcc,
+    L4Bender,
     Ld,
     Msvc,
     Lld(LldFlavor),
@@ -160,6 +161,7 @@ macro_rules! flavor_mappings {
 flavor_mappings! {
     ((LinkerFlavor::Em), "em"),
     ((LinkerFlavor::Gcc), "gcc"),
+    ((LinkerFlavor::L4Bender), "l4-bender"),
     ((LinkerFlavor::Ld), "ld"),
     ((LinkerFlavor::Msvc), "msvc"),
     ((LinkerFlavor::PtxLinker), "ptx-linker"),

compiler/rustc_target/src/spec/x86_64_unknown_l4re_uclibc.rs

@@ -11,6 +11,10 @@ pub fn target() -> Target {
         data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
             .to_string(),
         arch: "x86_64".to_string(),
+        target_os: "l4re".to_string(),
+        target_env: "uclibc".to_string(),
+        target_vendor: "unknown".to_string(),
+        linker_flavor: LinkerFlavor::L4Bender,
         options: base,
     }
 }