commit 9423c4f0dda638ec2a925140850b85e8d3e6d455 (from bee074f032970fd1b59650c04a70e75eeee9c63b)

Merge: bee074f03297 3a2a4429a288

Author: Mazdak Farrokhzad <twingoow@gmail.com>

Date:   Mon Mar 23 10:29:13 2020 +0100

    Rollup merge of #70123 - cuviper:library-path, r=Mark-Simulacrum

    Ensure LLVM is in the link path for rustc tools

    The build script for `rustc_llvm` outputs LLVM information in `cargo:rustc-link-lib` and `cargo:rustc-link-search` so the compiler can be linked correctly. However, while the lib is carried along in metadata, the search paths are not. So when cargo is invoked again later for rustc _tools_, they'll also try to link with LLVM, but the necessary paths may be left out.

    Rustbuild can use the environment to set the LLVM link path for tools -- `LIB` for MSVC toolchains and `LIBRARY_PATH` for everyone else.

    Fixes #68714.

diff --git a/src/bootstrap/builder.rs b/src/bootstrap/builder.rs

index 602e4511ea58..dd519506d42a 100644

--- a/src/bootstrap/builder.rs

+++ b/src/bootstrap/builder.rs

@@ -11,7 +11,7 @@ use std::path::{Path, PathBuf};

 use std::process::Command;

 use std::time::{Duration, Instant};

-use build_helper::t;

+use build_helper::{output, t};

 use crate::cache::{Cache, Interned, INTERNER};

 use crate::check;

@@ -23,7 +23,7 @@ use crate::install;

 use crate::native;

 use crate::test;

 use crate::tool;

-use crate::util::{self, add_lib_path, exe, libdir};

+use crate::util::{self, add_dylib_path, add_link_lib_path, exe, libdir};

 use crate::{Build, DocTests, GitRepo, Mode};

 pub use crate::Compiler;

@@ -660,7 +660,7 @@ impl<'a> Builder<'a> {

             return;

         }

-        add_lib_path(vec![self.rustc_libdir(compiler)], &mut cmd.command);

+        add_dylib_path(vec![self.rustc_libdir(compiler)], &mut cmd.command);

     }

     /// Gets a path to the compiler specified.

@@ -698,6 +698,20 @@ impl<'a> Builder<'a> {

         cmd

     }

+    /// Return the path to `llvm-config` for the target, if it exists.

+    ///

+    /// Note that this returns `None` if LLVM is disabled, or if we're in a

+    /// check build or dry-run, where there's no need to build all of LLVM.

+    fn llvm_config(&self, target: Interned<String>) -> Option<PathBuf> {

+        if self.config.llvm_enabled() && self.kind != Kind::Check && !self.config.dry_run {

+            let llvm_config = self.ensure(native::Llvm { target });

+            if llvm_config.is_file() {

+                return Some(llvm_config);

+            }

+        }

+        None

+    }

+

     /// Prepares an invocation of `cargo` to be run.

     ///

     /// This will create a `Command` that represents a pending execution of

@@ -1034,6 +1048,17 @@ impl<'a> Builder<'a> {

                 .env("RUSTC_SNAPSHOT_LIBDIR", self.rustc_libdir(compiler));

         }

+        // Tools that use compiler libraries may inherit the `-lLLVM` link

+        // requirement, but the `-L` library path is not propagated across

+        // separate Cargo projects. We can add LLVM's library path to the

+        // platform-specific environment variable as a workaround.

+        if mode == Mode::ToolRustc {

+            if let Some(llvm_config) = self.llvm_config(target) {

+                let llvm_libdir = output(Command::new(&llvm_config).arg("--libdir"));

+                add_link_lib_path(vec![llvm_libdir.trim().into()], &mut cargo);

+            }

+        }

+

         if self.config.incremental {

             cargo.env("CARGO_INCREMENTAL", "1");

         } else {

diff --git a/src/bootstrap/compile.rs b/src/bootstrap/compile.rs

index 65a00db33949..ad494b88b3af 100644

--- a/src/bootstrap/compile.rs

+++ b/src/bootstrap/compile.rs

@@ -451,44 +451,6 @@ impl Step for Rustc {

             false,

         );

-        // We used to build librustc_codegen_llvm as a separate step,

-        // which produced a dylib that the compiler would dlopen() at runtime.

-        // This meant that we only needed to make sure that libLLVM.so was

-        // installed by the time we went to run a tool using it - since

-        // librustc_codegen_llvm was effectively a standalone artifact,

-        // other crates were completely oblivious to its dependency

-        // on `libLLVM.so` during build time.

-        //

-        // However, librustc_codegen_llvm is now built as an ordinary

-        // crate during the same step as the rest of the compiler crates.

-        // This means that any crates depending on it will see the fact

-        // that it uses `libLLVM.so` as a native library, and will

-        // cause us to pass `-llibLLVM.so` to the linker when we link

-        // a binary.

-        //

-        // For `rustc` itself, this works out fine.

-        // During the `Assemble` step, we call `dist::maybe_install_llvm_dylib`

-        // to copy libLLVM.so into the `stage` directory. We then link

-        // the compiler binary, which will find `libLLVM.so` in the correct place.

-        //

-        // However, this is insufficient for tools that are build against stage0

-        // (e.g. stage1 rustdoc). Since `Assemble` for stage0 doesn't actually do anything,

-        // we won't have `libLLVM.so` in the stage0 sysroot. In the past, this wasn't

-        // a problem - we would copy the tool binary into its correct stage directory

-        // (e.g. stage1 for a stage1 rustdoc built against a stage0 compiler).

-        // Since libLLVM.so wasn't resolved until runtime, it was fine for it to

-        // not exist while we were building it.

-        //

-        // To ensure that we can still build stage1 tools against a stage0 compiler,

-        // we explicitly copy libLLVM.so into the stage0 sysroot when building

-        // the stage0 compiler. This ensures that tools built against stage0

-        // will see libLLVM.so at build time, making the linker happy.

-        if compiler.stage == 0 {

-            builder.info(&format!("Installing libLLVM.so to stage 0 ({})", compiler.host));

-            let sysroot = builder.sysroot(compiler);

-            dist::maybe_install_llvm_dylib(builder, compiler.host, &sysroot);

-        }

-

         builder.ensure(RustcLink {

             compiler: builder.compiler(compiler.stage, builder.config.build),

             target_compiler: compiler,

diff --git a/src/bootstrap/tool.rs b/src/bootstrap/tool.rs

index 67e0ed5c5802..c8ccba467e50 100644

--- a/src/bootstrap/tool.rs

+++ b/src/bootstrap/tool.rs

@@ -12,7 +12,7 @@ use crate::channel;

 use crate::channel::GitInfo;

 use crate::compile;

 use crate::toolstate::ToolState;

-use crate::util::{add_lib_path, exe, CiEnv};

+use crate::util::{add_dylib_path, exe, CiEnv};

 use crate::Compiler;

 use crate::Mode;

@@ -388,7 +388,7 @@ pub struct ErrorIndex {

 impl ErrorIndex {

     pub fn command(builder: &Builder<'_>, compiler: Compiler) -> Command {

         let mut cmd = Command::new(builder.ensure(ErrorIndex { compiler }));

-        add_lib_path(

+        add_dylib_path(

             vec![PathBuf::from(&builder.sysroot_libdir(compiler, compiler.host))],

             &mut cmd,

         );

@@ -689,7 +689,7 @@ impl<'a> Builder<'a> {

             }

         }

-        add_lib_path(lib_paths, &mut cmd);

+        add_dylib_path(lib_paths, &mut cmd);

         cmd

     }

 }

diff --git a/src/bootstrap/util.rs b/src/bootstrap/util.rs

index eac790fe504b..2bc6f1939d97 100644

--- a/src/bootstrap/util.rs

+++ b/src/bootstrap/util.rs

@@ -40,7 +40,7 @@ pub fn libdir(target: &str) -> &'static str {

 }

 /// Adds a list of lookup paths to `cmd`'s dynamic library lookup path.

-pub fn add_lib_path(path: Vec<PathBuf>, cmd: &mut Command) {

+pub fn add_dylib_path(path: Vec<PathBuf>, cmd: &mut Command) {

     let mut list = dylib_path();

     for path in path {

         list.insert(0, path);

@@ -72,6 +72,31 @@ pub fn dylib_path() -> Vec<PathBuf> {

     env::split_paths(&var).collect()

 }

+/// Adds a list of lookup paths to `cmd`'s link library lookup path.

+pub fn add_link_lib_path(path: Vec<PathBuf>, cmd: &mut Command) {

+    let mut list = link_lib_path();

+    for path in path {

+        list.insert(0, path);

+    }

+    cmd.env(link_lib_path_var(), t!(env::join_paths(list)));

+}

+

+/// Returns the environment variable which the link library lookup path

+/// resides in for this platform.

+fn link_lib_path_var() -> &'static str {

+    if cfg!(target_env = "msvc") { "LIB" } else { "LIBRARY_PATH" }

+}

+

+/// Parses the `link_lib_path_var()` environment variable, returning a list of

+/// paths that are members of this lookup path.

+fn link_lib_path() -> Vec<PathBuf> {

+    let var = match env::var_os(link_lib_path_var()) {

+        Some(v) => v,

+        None => return vec![],

+    };

+    env::split_paths(&var).collect()

+}

+

 /// `push` all components to `buf`. On windows, append `.exe` to the last component.

 pub fn push_exe_path(mut buf: PathBuf, components: &[&str]) -> PathBuf {

     let (&file, components) = components.split_last().expect("at least one component required");