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// Copyright 2014 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your // option. This file may not be copied, modified, or distributed // except according to those terms. use target::TargetOptions; use std::default::Default; pub fn opts() -> TargetOptions { TargetOptions { // FIXME(#13846) this should be enabled for windows function_sections: false, linker: "gcc".to_string(), dynamic_linking: true, executables: true, dll_prefix: "".to_string(), dll_suffix: ".dll".to_string(), exe_suffix: ".exe".to_string(), staticlib_prefix: "".to_string(), staticlib_suffix: ".lib".to_string(), no_default_libraries: true, target_family: Some("windows".to_string()), is_like_windows: true, allows_weak_linkage: false, pre_link_args: vec![ // And here, we see obscure linker flags #45. On windows, it has been // found to be necessary to have this flag to compile liblibc. // // First a bit of background. On Windows, the file format is not ELF, // but COFF (at least according to LLVM). COFF doesn't officially allow // for section names over 8 characters, apparently. Our metadata // section, ".note.rustc", you'll note is over 8 characters. // // On more recent versions of gcc on mingw, apparently the section name // is *not* truncated, but rather stored elsewhere in a separate lookup // table. On older versions of gcc, they apparently always truncated th // section names (at least in some cases). Truncating the section name // actually creates "invalid" objects [1] [2], but only for some // introspection tools, not in terms of whether it can be loaded. // // Long story short, passing this flag forces the linker to *not* // truncate section names (so we can find the metadata section after // it's compiled). The real kicker is that rust compiled just fine on // windows for quite a long time *without* this flag, so I have no idea // why it suddenly started failing for liblibc. Regardless, we // definitely don't want section name truncation, so we're keeping this // flag for windows. // // [1] - https://sourceware.org/bugzilla/show_bug.cgi?id=13130 // [2] - https://code.google.com/p/go/issues/detail?id=2139 "-Wl,--enable-long-section-names".to_string(), // Tell GCC to avoid linker plugins, because we are not bundling // them with Windows installer, and Rust does its own LTO anyways. "-fno-use-linker-plugin".to_string(), // Always enable DEP (NX bit) when it is available "-Wl,--nxcompat".to_string(), // Do not use the standard system startup files or libraries when linking "-nostdlib".to_string(), ], pre_link_objects_exe: vec![ "crt2.o".to_string(), // mingw C runtime initialization for executables "rsbegin.o".to_string(), // Rust compiler runtime initialization, see rsbegin.rs ], pre_link_objects_dll: vec![ "dllcrt2.o".to_string(), // mingw C runtime initialization for dlls "rsbegin.o".to_string(), ], late_link_args: vec![ "-lmingwex".to_string(), "-lmingw32".to_string(), "-lgcc".to_string(), // alas, mingw* libraries above depend on libgcc "-lmsvcrt".to_string(), "-luser32".to_string(), "-lkernel32".to_string(), ], post_link_objects: vec![ "rsend.o".to_string() ], custom_unwind_resume: true, .. Default::default() } }