libcxx: Add settings to build with libcxx as default C++ standard library

Signed-off-by: Robin Lee <cheeselee@fedoraproject>

3 files changed, 25 insertions, 1 deletions

diff --git a/README.md b/README.md
index d63060d..986f77c 100644
--- a/README.md
+++ b/README.md
@@ -39,6 +39,22 @@ you can select clang per package too by writing bbappends for them containing
 TOOLCHAIN = "clang"
 ```
 
+# Default C++ Standard Library Switch
+
+Note that by default libstdc++ will remain the default C++ standard library, however if you wish
+libc++ to be the default one then set
+
+```python
+TARGET_CXXFLAGS_append_toolchain-clang ?= " -stdlib=libc++ "
+```
+
+in local.conf.
+You can select libc++ per package too by writing bbappends for them containing
+
+```python
+TARGET_CXXFLAGS_append_toolchain-clang = " -stdlib=libc++ "
+```
+
 # Building
 
 Below we build for qemuarm machine as an example
@@ -61,7 +77,13 @@ simply add it to conf/nonclangable.inc e.g.
 TOOLCHAIN_pn-<recipe> = "gcc"
 ```
 
-and OE will start using gcc to cross compile that recipe,
+and OE will start using gcc to cross compile that recipe.
+
+And if a component does not build with libc++, you can add it to conf/nonclangable.inc e.g.
+
+```shell
+TARGET_CXXFLAGS_remove_pn-<recipe>_toolchain-clang = " -stdlib=libc++ "
+```
 
 # Dependencies
 
diff --git a/recipes-devtools/clang/compiler-rt_git.bb b/recipes-devtools/clang/compiler-rt_git.bb
index 834d2d6..ae21806 100644
--- a/recipes-devtools/clang/compiler-rt_git.bb
+++ b/recipes-devtools/clang/compiler-rt_git.bb
@@ -27,6 +27,7 @@ SRCREV_FORMAT = "compiler-rt"
 
 BASEDEPENDS_remove_toolchain-clang_class-target = "compiler-rt"
 BASEDEPENDS_remove_toolchain-clang_class-target = "libcxx"
+TARGET_CXXFLAGS_remove_toolchain-clang = " -stdlib=libc++ "
 
 DEPENDS += "ninja-native"
 
diff --git a/recipes-devtools/clang/libcxx_git.bb b/recipes-devtools/clang/libcxx_git.bb
index 0f3b2a8..57f0654 100644
--- a/recipes-devtools/clang/libcxx_git.bb
+++ b/recipes-devtools/clang/libcxx_git.bb
@@ -14,6 +14,7 @@ PV .= "+git${SRCPV}"
 
 DEPENDS += "ninja-native"
 BASEDEPENDS_remove_toolchain-clang_class-target = "libcxx"
+TARGET_CXXFLAGS_remove_toolchain-clang = " -stdlib=libc++ "
 
 PROVIDES = "libunwind"
 PROVIDES_remove_mipsarch = "libunwind"