From 43893f726d481cc9184d5a23311d21b4fcdd4909 Mon Sep 17 00:00:00 2001
From: Arthur Silva <arthurprs@gmail.com>
Date: Wed, 16 Mar 2022 16:20:09 +0100
Subject: [PATCH] Add crate feature that controls whether custom libcxx is used
 (#924)

The `use_custom_libcxx` feature is enabled by default. When this feature
is disabled, the crate will link with the system libcxx instead.
---
 Cargo.toml |  4 ++++
 build.rs   | 26 ++++++++++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/Cargo.toml b/Cargo.toml
index 4b5316be..ab4f047e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -75,6 +75,10 @@ exclude = [
  "!v8/tools/testrunner/utils/dump_build_config.py",
 ]
 
+[features]
+default = ["use_custom_libcxx"]
+use_custom_libcxx = []
+
 [dependencies]
 lazy_static = "1.4.0"
 libc = "0.2.93"
diff --git a/build.rs b/build.rs
index 19bcf30e..44019dd6 100644
--- a/build.rs
+++ b/build.rs
@@ -109,6 +109,10 @@ fn build_v8() {
     vec!["is_debug=false".to_string()]
   };
 
+  if cfg!(not(feature = "use_custom_libcxx")) {
+    gn_args.push("use_custom_libcxx=false".to_string());
+  }
+
   if !is_debug() {
     gn_args.push("v8_enable_handle_zapping=false".to_string());
   }
@@ -398,6 +402,28 @@ fn download_static_lib_binaries() {
 fn print_link_flags() {
   println!("cargo:rustc-link-lib=static=rusty_v8");
 
+  let should_dyn_link_libcxx = cfg!(not(feature = "use_custom_libcxx"))
+    || env::var("GN_ARGS").map_or(false, |gn_args| {
+      gn_args
+        .split_whitespace()
+        .any(|ba| ba == "use_custom_libcxx=false")
+    });
+
+  if should_dyn_link_libcxx {
+    // Based on https://github.com/alexcrichton/cc-rs/blob/fba7feded71ee4f63cfe885673ead6d7b4f2f454/src/lib.rs#L2462
+    let target = env::var("TARGET").unwrap();
+    if target.contains("apple")
+      || target.contains("freebsd")
+      || target.contains("openbsd")
+    {
+      println!("cargo:rustc-link-lib=dylib=c++");
+    } else if target.contains("linux") {
+      println!("cargo:rustc-link-lib=dylib=stdc++");
+    } else if target.contains("android") {
+      println!("cargo:rustc-link-lib=dylib=c++_shared");
+    }
+  }
+
   if cfg!(target_os = "windows") {
     println!("cargo:rustc-link-lib=dylib=winmm");
     println!("cargo:rustc-link-lib=dylib=dbghelp");