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Add no_default_libraries target linker option
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If set to false, `-nodefaultlibs` is not passed to the linker. This
was the default behavior on Windows, but it should be configurable
per target.

This is a [breaking-change] for target specifications that have
the `is_like_windows` option set to true. Such targets need to
set `no_default_libraries` to false in order to restore the old
behavior.
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gandro committed Sep 21, 2015
1 parent 7e8d19b commit 920f32b
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Showing 4 changed files with 13 additions and 7 deletions.
5 changes: 5 additions & 0 deletions src/librustc_back/target/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -157,6 +157,9 @@ pub struct TargetOptions {
/// Whether to disable linking to compiler-rt. Defaults to false, as LLVM
/// will emit references to the functions that compiler-rt provides.
pub no_compiler_rt: bool,
/// Whether to disable linking to the default libraries, typically corresponds
/// to `-nodefaultlibs`. Defaults to true.
pub no_default_libraries: bool,
/// Dynamically linked executables can be compiled as position independent
/// if the default relocation model of position independent code is not
/// changed. This is a requirement to take advantage of ASLR, as otherwise
Expand Down Expand Up @@ -212,6 +215,7 @@ impl Default for TargetOptions {
linker_is_gnu: false,
has_rpath: false,
no_compiler_rt: false,
no_default_libraries: true,
position_independent_executables: false,
pre_link_objects: Vec::new(),
post_link_objects: Vec::new(),
Expand Down Expand Up @@ -319,6 +323,7 @@ impl Target {
key!(linker_is_gnu, bool);
key!(has_rpath, bool);
key!(no_compiler_rt, bool);
key!(no_default_libraries, bool);
key!(pre_link_args, list);
key!(post_link_args, list);
key!(allow_asm, bool);
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4 changes: 4 additions & 0 deletions src/librustc_back/target/windows_base.rs
Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,10 @@ pub fn opts() -> TargetOptions {
exe_suffix: ".exe".to_string(),
staticlib_prefix: "".to_string(),
staticlib_suffix: ".lib".to_string(),
// Unfortunately right now passing -nodefaultlibs to gcc on windows
// doesn't work so hot (in terms of native dependencies). This flag
// should hopefully be removed one day though!
no_default_libraries: false,
is_like_windows: true,
archive_format: "gnu".to_string(),
pre_link_args: vec!(
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4 changes: 3 additions & 1 deletion src/librustc_trans/back/link.rs
Original file line number Diff line number Diff line change
Expand Up @@ -970,7 +970,9 @@ fn link_args(cmd: &mut Linker,
// default. Note that this does not happen for windows because windows pulls
// in some large number of libraries and I couldn't quite figure out which
// subset we wanted.
cmd.no_default_libraries();
if t.options.no_default_libraries {
cmd.no_default_libraries();
}

// Take careful note of the ordering of the arguments we pass to the linker
// here. Linkers will assume that things on the left depend on things to the
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7 changes: 1 addition & 6 deletions src/librustc_trans/back/linker.rs
Original file line number Diff line number Diff line change
Expand Up @@ -159,12 +159,7 @@ impl<'a> Linker for GnuLinker<'a> {
}

fn no_default_libraries(&mut self) {
// Unfortunately right now passing -nodefaultlibs to gcc on windows
// doesn't work so hot (in terms of native dependencies). This if
// statement should hopefully be removed one day though!
if !self.sess.target.target.options.is_like_windows {
self.cmd.arg("-nodefaultlibs");
}
self.cmd.arg("-nodefaultlibs");
}

fn build_dylib(&mut self, out_filename: &Path) {
Expand Down

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