src/librustc_llvm/build.rs - third_party/rust - Git at Google

 use std::process::Command;
 use std::env;
 use std::path::{PathBuf, Path};

 use build_helper::output;

 fn detect_llvm_link() -> (&'static str, &'static str) {
     // Force the link mode we want, preferring static by default, but
     // possibly overridden by `configure --enable-llvm-link-shared`.
     if env::var_os("LLVM_LINK_SHARED").is_some() {
         ("dylib", "--link-shared")
     } else {
         ("static", "--link-static")
     }
 }

 fn main() {
     if env::var_os("RUST_CHECK").is_some() {
         // If we're just running `check`, there's no need for LLVM to be built.
         println!("cargo:rerun-if-env-changed=RUST_CHECK");
         return;
     }

     build_helper::restore_library_path();

     let target = env::var("TARGET").expect("TARGET was not set");
     let llvm_config = env::var_os("LLVM_CONFIG")
         .map(PathBuf::from)
         .unwrap_or_else(|| {
             if let Some(dir) = env::var_os("CARGO_TARGET_DIR").map(PathBuf::from) {
                 let to_test = dir.parent()
                     .unwrap()
                     .parent()
                     .unwrap()
                     .join(&target)
                     .join("llvm/bin/llvm-config");
                 if Command::new(&to_test).output().is_ok() {
                     return to_test;
                 }
             }
             PathBuf::from("llvm-config")
         });

     println!("cargo:rerun-if-changed={}", llvm_config.display());
     println!("cargo:rerun-if-env-changed=LLVM_CONFIG");

     // Test whether we're cross-compiling LLVM. This is a pretty rare case
     // currently where we're producing an LLVM for a different platform than
     // what this build script is currently running on.
     //
     // In that case, there's no guarantee that we can actually run the target,
     // so the build system works around this by giving us the LLVM_CONFIG for
     // the host platform. This only really works if the host LLVM and target
     // LLVM are compiled the same way, but for us that's typically the case.
     //
     // We *want* detect this cross compiling situation by asking llvm-config
     // what it's host-target is. If that's not the TARGET, then we're cross
     // compiling. Unfortunately `llvm-config` seems either be buggy, or we're
     // misconfiguring it, because the `i686-pc-windows-gnu` build of LLVM will
     // report itself with a `--host-target` of `x86_64-pc-windows-gnu`. This
     // tricks us into thinking we're doing a cross build when we aren't, so
     // havoc ensues.
     //
     // In any case, if we're cross compiling, this generally just means that we
     // can't trust all the output of llvm-config becaues it might be targeted
     // for the host rather than the target. As a result a bunch of blocks below
     // are gated on `if !is_crossed`
     let target = env::var("TARGET").expect("TARGET was not set");
     let host = env::var("HOST").expect("HOST was not set");
     let is_crossed = target != host;

     let mut optional_components =
         vec!["x86", "arm", "aarch64", "amdgpu", "mips", "powerpc",
              "systemz", "jsbackend", "webassembly", "msp430", "sparc", "nvptx",
              "hexagon"];

     let mut version_cmd = Command::new(&llvm_config);
     version_cmd.arg("--version");
     let version_output = output(&mut version_cmd);
     let mut parts = version_output.split('.').take(2)
         .filter_map(|s| s.parse::<u32>().ok());
     let (major, _minor) =
         if let (Some(major), Some(minor)) = (parts.next(), parts.next()) {
             (major, minor)
         } else {
             (6, 0)
         };

     if major > 6 {
         optional_components.push("riscv");
     }

     let required_components = &["ipo",
                                 "bitreader",
                                 "bitwriter",
                                 "linker",
                                 "asmparser",
                                 "lto",
                                 "instrumentation"];

     let components = output(Command::new(&llvm_config).arg("--components"));
     let mut components = components.split_whitespace().collect::<Vec<_>>();
     components.retain(|c| optional_components.contains(c) || required_components.contains(c));

     for component in required_components {
         if !components.contains(component) {
             panic!("require llvm component {} but wasn't found", component);
         }
     }

     for component in components.iter() {
         println!("cargo:rustc-cfg=llvm_component=\"{}\"", component);
     }

     if major >= 9 {
         println!("cargo:rustc-cfg=llvm_has_msp430_asm_parser");
     }

     // Link in our own LLVM shims, compiled with the same flags as LLVM
     let mut cmd = Command::new(&llvm_config);
     cmd.arg("--cxxflags");
     let cxxflags = output(&mut cmd);
     let mut cfg = cc::Build::new();
     cfg.warnings(false);
     for flag in cxxflags.split_whitespace() {
         // Ignore flags like `-m64` when we're doing a cross build
         if is_crossed && flag.starts_with("-m") {
             continue;
         }

         if flag.starts_with("-flto") {
             continue;
         }

         // -Wdate-time is not supported by the netbsd cross compiler
         if is_crossed && target.contains("netbsd") && flag.contains("date-time") {
             continue;
         }

         cfg.flag(flag);
     }

     for component in &components {
         let mut flag = String::from("LLVM_COMPONENT_");
         flag.push_str(&component.to_uppercase());
         cfg.define(&flag, None);
     }

     println!("cargo:rerun-if-changed-env=LLVM_RUSTLLVM");
     if env::var_os("LLVM_RUSTLLVM").is_some() {
         cfg.define("LLVM_RUSTLLVM", None);
     }

     if env::var_os("LLVM_NDEBUG").is_some() {
         cfg.define("NDEBUG", None);
     }

     build_helper::rerun_if_changed_anything_in_dir(Path::new("../rustllvm"));
     cfg.file("../rustllvm/PassWrapper.cpp")
        .file("../rustllvm/RustWrapper.cpp")
        .file("../rustllvm/ArchiveWrapper.cpp")
        .file("../rustllvm/Linker.cpp")
        .cpp(true)
        .cpp_link_stdlib(None) // we handle this below
        .compile("rustllvm");

     let (llvm_kind, llvm_link_arg) = detect_llvm_link();

     // Link in all LLVM libraries, if we're uwring the "wrong" llvm-config then
     // we don't pick up system libs because unfortunately they're for the host
     // of llvm-config, not the target that we're attempting to link.
     let mut cmd = Command::new(&llvm_config);
     cmd.arg(llvm_link_arg).arg("--libs");

     if !is_crossed {
         cmd.arg("--system-libs");
     }
     cmd.args(&components);

     for lib in output(&mut cmd).split_whitespace() {
         let name = if lib.starts_with("-l") {
             &lib[2..]
         } else if lib.starts_with("-") {
             &lib[1..]
         } else if Path::new(lib).exists() {
             // On MSVC llvm-config will print the full name to libraries, but
             // we're only interested in the name part
             let name = Path::new(lib).file_name().unwrap().to_str().unwrap();
             name.trim_end_matches(".lib")
         } else if lib.ends_with(".lib") {
             // Some MSVC libraries just come up with `.lib` tacked on, so chop
             // that off
             lib.trim_end_matches(".lib")
         } else {
             continue;
         };

         // Don't need or want this library, but LLVM's CMake build system
         // doesn't provide a way to disable it, so filter it here even though we
         // may or may not have built it. We don't reference anything from this
         // library and it otherwise may just pull in extra dependencies on
         // libedit which we don't want
         if name == "LLVMLineEditor" {
             continue;
         }

         let kind = if name.starts_with("LLVM") {
             llvm_kind
         } else {
             "dylib"
         };
         println!("cargo:rustc-link-lib={}={}", kind, name);
     }

     // LLVM ldflags
     //
     // If we're a cross-compile of LLVM then unfortunately we can't trust these
     // ldflags (largely where all the LLVM libs are located). Currently just
     // hack around this by replacing the host triple with the target and pray
     // that those -L directories are the same!
     let mut cmd = Command::new(&llvm_config);
     cmd.arg(llvm_link_arg).arg("--ldflags");
     for lib in output(&mut cmd).split_whitespace() {
         if lib.starts_with("-LIBPATH:") {
             println!("cargo:rustc-link-search=native={}", &lib[9..]);
         } else if is_crossed {
             if lib.starts_with("-L") {
                 println!("cargo:rustc-link-search=native={}",
                          lib[2..].replace(&host, &target));
             }
         } else if lib.starts_with("-l") {
             println!("cargo:rustc-link-lib={}", &lib[2..]);
         } else if lib.starts_with("-L") {
             println!("cargo:rustc-link-search=native={}", &lib[2..]);
         }
     }

     // Some LLVM linker flags (-L and -l) may be needed even when linking
     // librustc_llvm, for example when using static libc++, we may need to
     // manually specify the library search path and -ldl -lpthread as link
     // dependencies.
     let llvm_linker_flags = env::var_os("LLVM_LINKER_FLAGS");
     if let Some(s) = llvm_linker_flags {
         for lib in s.into_string().unwrap().split_whitespace() {
             if lib.starts_with("-l") {
                 println!("cargo:rustc-link-lib={}", &lib[2..]);
             } else if lib.starts_with("-L") {
                 println!("cargo:rustc-link-search=native={}", &lib[2..]);
             }
         }
     }

     let llvm_static_stdcpp = env::var_os("LLVM_STATIC_STDCPP");
     let llvm_use_libcxx = env::var_os("LLVM_USE_LIBCXX");

     let stdcppname = if target.contains("openbsd") {
         if target.contains("sparc64") {
             "estdc++"
         } else {
             "c++"
         }
     } else if target.contains("freebsd") {
         "c++"
     } else if target.contains("darwin") {
         "c++"
     } else if target.contains("netbsd") && llvm_static_stdcpp.is_some() {
         // NetBSD uses a separate library when relocation is required
         "stdc++_pic"
     } else if llvm_use_libcxx.is_some() {
         "c++"
     } else {
         "stdc++"
     };

     // C++ runtime library
     if !target.contains("msvc") {
         if let Some(s) = llvm_static_stdcpp {
             assert!(!cxxflags.contains("stdlib=libc++"));
             let path = PathBuf::from(s);
             println!("cargo:rustc-link-search=native={}",
                      path.parent().unwrap().display());
             println!("cargo:rustc-link-lib=static={}", stdcppname);
         } else if cxxflags.contains("stdlib=libc++") {
             println!("cargo:rustc-link-lib=c++");
         } else {
             println!("cargo:rustc-link-lib={}", stdcppname);
         }
     }

     // LLVM requires symbols from this library, but apparently they're not printed
     // during llvm-config?
     if target.contains("windows-gnu") {
         println!("cargo:rustc-link-lib=static-nobundle=gcc_s");
         println!("cargo:rustc-link-lib=static-nobundle=pthread");
         println!("cargo:rustc-link-lib=dylib=uuid");
     }
 }
	use std::process::Command;
	use std::env;
	use std::path::{PathBuf, Path};

	use build_helper::output;

	fn detect_llvm_link() -> (&'static str, &'static str) {
	// Force the link mode we want, preferring static by default, but
	// possibly overridden by `configure --enable-llvm-link-shared`.
	if env::var_os("LLVM_LINK_SHARED").is_some() {
	("dylib", "--link-shared")
	} else {
	("static", "--link-static")
	}
	}

	fn main() {
	if env::var_os("RUST_CHECK").is_some() {
	// If we're just running `check`, there's no need for LLVM to be built.
	println!("cargo:rerun-if-env-changed=RUST_CHECK");
	return;
	}

	build_helper::restore_library_path();

	let target = env::var("TARGET").expect("TARGET was not set");
	let llvm_config = env::var_os("LLVM_CONFIG")
	.map(PathBuf::from)
	.unwrap_or_else(\|\| {
	if let Some(dir) = env::var_os("CARGO_TARGET_DIR").map(PathBuf::from) {
	let to_test = dir.parent()
	.unwrap()
	.parent()
	.unwrap()
	.join(&target)
	.join("llvm/bin/llvm-config");
	if Command::new(&to_test).output().is_ok() {
	return to_test;
	}
	}
	PathBuf::from("llvm-config")
	});

	println!("cargo:rerun-if-changed={}", llvm_config.display());
	println!("cargo:rerun-if-env-changed=LLVM_CONFIG");

	// Test whether we're cross-compiling LLVM. This is a pretty rare case
	// currently where we're producing an LLVM for a different platform than
	// what this build script is currently running on.
	//
	// In that case, there's no guarantee that we can actually run the target,
	// so the build system works around this by giving us the LLVM_CONFIG for
	// the host platform. This only really works if the host LLVM and target
	// LLVM are compiled the same way, but for us that's typically the case.
	//
	// We want detect this cross compiling situation by asking llvm-config
	// what it's host-target is. If that's not the TARGET, then we're cross
	// compiling. Unfortunately `llvm-config` seems either be buggy, or we're
	// misconfiguring it, because the `i686-pc-windows-gnu` build of LLVM will
	// report itself with a `--host-target` of `x86_64-pc-windows-gnu`. This
	// tricks us into thinking we're doing a cross build when we aren't, so
	// havoc ensues.
	//
	// In any case, if we're cross compiling, this generally just means that we
	// can't trust all the output of llvm-config becaues it might be targeted
	// for the host rather than the target. As a result a bunch of blocks below
	// are gated on `if !is_crossed`
	let target = env::var("TARGET").expect("TARGET was not set");
	let host = env::var("HOST").expect("HOST was not set");
	let is_crossed = target != host;

	let mut optional_components =
	vec!["x86", "arm", "aarch64", "amdgpu", "mips", "powerpc",
	"systemz", "jsbackend", "webassembly", "msp430", "sparc", "nvptx",
	"hexagon"];

	let mut version_cmd = Command::new(&llvm_config);
	version_cmd.arg("--version");
	let version_output = output(&mut version_cmd);
	let mut parts = version_output.split('.').take(2)
	.filter_map(\|s\| s.parse::<u32>().ok());
	let (major, _minor) =
	if let (Some(major), Some(minor)) = (parts.next(), parts.next()) {
	(major, minor)
	} else {
	(6, 0)
	};

	if major > 6 {
	optional_components.push("riscv");
	}

	let required_components = &["ipo",
	"bitreader",
	"bitwriter",
	"linker",
	"asmparser",
	"lto",
	"instrumentation"];

	let components = output(Command::new(&llvm_config).arg("--components"));
	let mut components = components.split_whitespace().collect::<Vec<_>>();
	components.retain(\|c\| optional_components.contains(c) \|\| required_components.contains(c));

	for component in required_components {
	if !components.contains(component) {
	panic!("require llvm component {} but wasn't found", component);
	}
	}

	for component in components.iter() {
	println!("cargo:rustc-cfg=llvm_component=\"{}\"", component);
	}

	if major >= 9 {
	println!("cargo:rustc-cfg=llvm_has_msp430_asm_parser");
	}

	// Link in our own LLVM shims, compiled with the same flags as LLVM
	let mut cmd = Command::new(&llvm_config);
	cmd.arg("--cxxflags");
	let cxxflags = output(&mut cmd);
	let mut cfg = cc::Build::new();
	cfg.warnings(false);
	for flag in cxxflags.split_whitespace() {
	// Ignore flags like `-m64` when we're doing a cross build
	if is_crossed && flag.starts_with("-m") {
	continue;
	}

	if flag.starts_with("-flto") {
	continue;
	}

	// -Wdate-time is not supported by the netbsd cross compiler
	if is_crossed && target.contains("netbsd") && flag.contains("date-time") {
	continue;
	}

	cfg.flag(flag);
	}

	for component in &components {
	let mut flag = String::from("LLVM_COMPONENT_");
	flag.push_str(&component.to_uppercase());
	cfg.define(&flag, None);
	}

	println!("cargo:rerun-if-changed-env=LLVM_RUSTLLVM");
	if env::var_os("LLVM_RUSTLLVM").is_some() {
	cfg.define("LLVM_RUSTLLVM", None);
	}

	if env::var_os("LLVM_NDEBUG").is_some() {
	cfg.define("NDEBUG", None);
	}

	build_helper::rerun_if_changed_anything_in_dir(Path::new("../rustllvm"));
	cfg.file("../rustllvm/PassWrapper.cpp")
	.file("../rustllvm/RustWrapper.cpp")
	.file("../rustllvm/ArchiveWrapper.cpp")
	.file("../rustllvm/Linker.cpp")
	.cpp(true)
	.cpp_link_stdlib(None) // we handle this below
	.compile("rustllvm");

	let (llvm_kind, llvm_link_arg) = detect_llvm_link();

	// Link in all LLVM libraries, if we're uwring the "wrong" llvm-config then
	// we don't pick up system libs because unfortunately they're for the host
	// of llvm-config, not the target that we're attempting to link.
	let mut cmd = Command::new(&llvm_config);
	cmd.arg(llvm_link_arg).arg("--libs");

	if !is_crossed {
	cmd.arg("--system-libs");
	}
	cmd.args(&components);

	for lib in output(&mut cmd).split_whitespace() {
	let name = if lib.starts_with("-l") {
	&lib[2..]
	} else if lib.starts_with("-") {
	&lib[1..]
	} else if Path::new(lib).exists() {
	// On MSVC llvm-config will print the full name to libraries, but
	// we're only interested in the name part
	let name = Path::new(lib).file_name().unwrap().to_str().unwrap();
	name.trim_end_matches(".lib")
	} else if lib.ends_with(".lib") {
	// Some MSVC libraries just come up with `.lib` tacked on, so chop
	// that off
	lib.trim_end_matches(".lib")
	} else {
	continue;
	};

	// Don't need or want this library, but LLVM's CMake build system
	// doesn't provide a way to disable it, so filter it here even though we
	// may or may not have built it. We don't reference anything from this
	// library and it otherwise may just pull in extra dependencies on
	// libedit which we don't want
	if name == "LLVMLineEditor" {
	continue;
	}

	let kind = if name.starts_with("LLVM") {
	llvm_kind
	} else {
	"dylib"
	};
	println!("cargo:rustc-link-lib={}={}", kind, name);
	}

	// LLVM ldflags
	//
	// If we're a cross-compile of LLVM then unfortunately we can't trust these
	// ldflags (largely where all the LLVM libs are located). Currently just
	// hack around this by replacing the host triple with the target and pray
	// that those -L directories are the same!
	let mut cmd = Command::new(&llvm_config);
	cmd.arg(llvm_link_arg).arg("--ldflags");
	for lib in output(&mut cmd).split_whitespace() {
	if lib.starts_with("-LIBPATH:") {
	println!("cargo:rustc-link-search=native={}", &lib[9..]);
	} else if is_crossed {
	if lib.starts_with("-L") {
	println!("cargo:rustc-link-search=native={}",
	lib[2..].replace(&host, &target));
	}
	} else if lib.starts_with("-l") {
	println!("cargo:rustc-link-lib={}", &lib[2..]);
	} else if lib.starts_with("-L") {
	println!("cargo:rustc-link-search=native={}", &lib[2..]);
	}
	}

	// Some LLVM linker flags (-L and -l) may be needed even when linking
	// librustc_llvm, for example when using static libc++, we may need to
	// manually specify the library search path and -ldl -lpthread as link
	// dependencies.
	let llvm_linker_flags = env::var_os("LLVM_LINKER_FLAGS");
	if let Some(s) = llvm_linker_flags {
	for lib in s.into_string().unwrap().split_whitespace() {
	if lib.starts_with("-l") {
	println!("cargo:rustc-link-lib={}", &lib[2..]);
	} else if lib.starts_with("-L") {
	println!("cargo:rustc-link-search=native={}", &lib[2..]);
	}
	}
	}

	let llvm_static_stdcpp = env::var_os("LLVM_STATIC_STDCPP");
	let llvm_use_libcxx = env::var_os("LLVM_USE_LIBCXX");

	let stdcppname = if target.contains("openbsd") {
	if target.contains("sparc64") {
	"estdc++"
	} else {
	"c++"
	}
	} else if target.contains("freebsd") {
	"c++"
	} else if target.contains("darwin") {
	"c++"
	} else if target.contains("netbsd") && llvm_static_stdcpp.is_some() {
	// NetBSD uses a separate library when relocation is required
	"stdc++_pic"
	} else if llvm_use_libcxx.is_some() {
	"c++"
	} else {
	"stdc++"
	};

	// C++ runtime library
	if !target.contains("msvc") {
	if let Some(s) = llvm_static_stdcpp {
	assert!(!cxxflags.contains("stdlib=libc++"));
	let path = PathBuf::from(s);
	println!("cargo:rustc-link-search=native={}",
	path.parent().unwrap().display());
	println!("cargo:rustc-link-lib=static={}", stdcppname);
	} else if cxxflags.contains("stdlib=libc++") {
	println!("cargo:rustc-link-lib=c++");
	} else {
	println!("cargo:rustc-link-lib={}", stdcppname);
	}
	}

	// LLVM requires symbols from this library, but apparently they're not printed
	// during llvm-config?
	if target.contains("windows-gnu") {
	println!("cargo:rustc-link-lib=static-nobundle=gcc_s");
	println!("cargo:rustc-link-lib=static-nobundle=pthread");
	println!("cargo:rustc-link-lib=dylib=uuid");
	}
	}