[meta-darwin][PATCH 17/21] darwin-common: add the nativesdk include dir to the header search path

[ecordonnier@snap.com]

From: Etienne Cordonnier <ecordonnier@snap.com>

gcc-crosssdk's built-in header search on Darwin only covers the OS SDK
tree (.../runtime/usr/include). Headers staged by our own nativesdk
recipes live one level up and are only found via an explicit -I, e.g.
nettle's gmp.h, curl's openssl/ssl.h (pkg-config drops the Cflags as a
"system" path), file's lzma.h and llvm's zstd.h.

Add -I${STAGING_INCDIR} to CPPFLAGS for every nativesdk recipe instead
of per recipe. cmake.bbclass only feeds CFLAGS/CXXFLAGS into the compile
flags, so llvm gets it through those, plus -F for the CoreFoundation
framework that dsymutil needs.

Tested by building nativesdk-nettle, nativesdk-curl, nativesdk-file and
nativesdk-llvm for x86_64-darwin.

AI-Generated: Claude Sonnet 5.5

Signed-off-by: Etienne Cordonnier <ecordonnier@snap.com>
---
 conf/machine-sdk/darwin-common.inc     |  6 ++++++
 recipes-devtools/clang/llvm_%.bbappend | 15 +++++++++++++++
 2 files changed, 21 insertions(+)
 create mode 100644 recipes-devtools/clang/llvm_%.bbappend

diff --git a/conf/machine-sdk/darwin-common.inc b/conf/machine-sdk/darwin-common.inc
index 1e3f03b..a23c605 100644
--- a/conf/machine-sdk/darwin-common.inc
+++ b/conf/machine-sdk/darwin-common.inc
@@ -91,3 +91,9 @@ fakeroot create_macos_img() {
 # every nativesdk/cross-canadian compiler command line, and those end up in
 # headers (e.g. gmp.h's __GMP_CC), libraries and binaries.
 ERROR_QA:remove = "buildpaths"
+
+# gcc's built-in header search on Darwin only covers the OS SDK include tree
+# (.../runtime/usr/include); headers staged by our own nativesdk recipes live
+# one level up and are only found via an explicit -I. Do this for every
+# nativesdk recipe instead of per recipe (see e.g. curl, nettle).
+CPPFLAGS:append:class-nativesdk = " -I${STAGING_INCDIR}"
diff --git a/recipes-devtools/clang/llvm_%.bbappend b/recipes-devtools/clang/llvm_%.bbappend
new file mode 100644
index 0000000..8565d67
--- /dev/null
+++ b/recipes-devtools/clang/llvm_%.bbappend
@@ -0,0 +1,15 @@
+# Unlike autotools recipes (nettle, curl), cmake.bbclass feeds CMAKE_C_FLAGS/
+# CMAKE_CXX_FLAGS from CFLAGS/CXXFLAGS only, not CPPFLAGS, so the usual
+# CPPFLAGS:append trick for missing nativesdk headers has no effect here.
+# zstd's headers are staged in the nested nativesdk sysroot, not the runtime
+# macOS SDK tree gcc's default search covers.
+CFLAGS:append:class-nativesdk:darwin21 = " -I${STAGING_INCDIR}"
+CXXFLAGS:append:class-nativesdk:darwin21 = " -I${STAGING_INCDIR}"
+
+# OSXSDK is only set in clang's own bbappend, which doesn't carry over to this
+# recipe's metadata, so redefine it here too.
+OSXSDK:class-nativesdk:darwin21 = "${STAGING_DIR_TARGET}${SDKPATHNATIVE}/runtime"
+
+# dsymutil (tools/dsymutil/CFBundle.cpp) needs the CoreFoundation framework;
+# frameworks need -F, not -I.
+CXXFLAGS:append:class-nativesdk:darwin21 = " -F${OSXSDK}/System/Library/Frameworks"
-- 
2.43.0