Provide the option to use libc++ even on all platforms

This is the default on platforms which use libc++ as the default C++
library but this option allows using libc++ on others as well.

3 files changed, 8 insertions, 0 deletions

diff --git a/src/bootstrap/compile.rs b/src/bootstrap/compile.rs
index 821bd002e95..6b6ead351e8 100644
--- a/src/bootstrap/compile.rs
+++ b/src/bootstrap/compile.rs
@@ -752,6 +752,9 @@ pub fn build_codegen_backend(builder: &Builder,
             if builder.config.llvm_link_shared {
                 cargo.env("LLVM_LINK_SHARED", "1");
             }
+            if builder.config.llvm_use_libcxx {
+                cargo.env("LLVM_USE_LIBCXX", "1");
+            }
         }
         _ => panic!("unknown backend: {}", backend),
     }
diff --git a/src/bootstrap/config.rs b/src/bootstrap/config.rs
index 8655cf0eb30..9421817ae6d 100644
--- a/src/bootstrap/config.rs
+++ b/src/bootstrap/config.rs
@@ -82,6 +82,8 @@ pub struct Config {
     pub lldb_enabled: bool,
     pub llvm_tools_enabled: bool,
 
+    pub llvm_use_libcxx: bool,
+
     // rust codegen options
     pub rust_optimize: bool,
     pub rust_codegen_units: Option<u32>,
@@ -252,6 +254,7 @@ struct Llvm {
     link_shared: Option<bool>,
     version_suffix: Option<String>,
     clang_cl: Option<String>,
+    use_libcxx: Option<bool>,
 }
 
 #[derive(Deserialize, Default, Clone)]
@@ -513,6 +516,7 @@ impl Config {
             config.llvm_link_jobs = llvm.link_jobs;
             config.llvm_version_suffix = llvm.version_suffix.clone();
             config.llvm_clang_cl = llvm.clang_cl.clone();
+            set(&mut config.llvm_use_libcxx, llvm.use_libcxx);
         }
 
         if let Some(ref rust) = toml.rust {
diff --git a/src/bootstrap/configure.py b/src/bootstrap/configure.py
index d13a3dc7834..b0c3c970249 100755
--- a/src/bootstrap/configure.py
+++ b/src/bootstrap/configure.py
@@ -62,6 +62,7 @@ o("full-tools", None, "enable all tools")
 o("lld", "rust.lld", "build lld")
 o("lldb", "rust.lldb", "build lldb")
 o("missing-tools", "dist.missing-tools", "allow failures when building tools")
+o("use-libcxx", "llvm.use_libcxx", "build LLVM with libc++")
 
 # Optimization and debugging options. These may be overridden by the release
 # channel, etc.