[Driver] Prioritize SYSROOT/usr/include over RESOURCE_DIR/include on linux-musl

On a musl-based Linux distribution, stdalign.h stdarg.h stdbool.h stddef.h stdint.h stdnoreturn.h are expected to be provided by musl (/usr/include), instead of RESOURCE_DIR/include.
Reorder RESOURCE_DIR/include to fix the search order problem.
(Currently musl doesn't provide stdatomic.h. stdatomic.h is still found in RESOURCE_DIR/include.)

gcc on musl has a similar search order:

```
 /usr/lib/gcc/x86_64-alpine-linux-musl/8.3.0/../../../../include/c++/8.3.0
 /usr/lib/gcc/x86_64-alpine-linux-musl/8.3.0/../../../../include/c++/8.3.0/x86_64-alpine-linux-musl
 /usr/lib/gcc/x86_64-alpine-linux-musl/8.3.0/../../../../include/c++/8.3.0/backward
 /usr/local/include
 /usr/include/fortify
 /usr/include
 /usr/lib/gcc/x86_64-alpine-linux-musl/8.3.0/include
```

This is different from a glibc-based distribution where RESOURCE_DIR/include is placed before SYSROOT/usr/include.

According to the maintainer of musl:

> musl does not support use/mixing of compiler-provided std headers with its headers, and intentionally has no mechanism for communicating with such headers as to which types have already been defined or still need to be defined. If the current include order, with clang's headers before the libc ones, works in some situations, it's only by accident.

Reviewed by: phosek

Differential Revision: https://reviews.llvm.org/D65699

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@367981 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Driver/ToolChains/Linux.cpp b/lib/Driver/ToolChains/Linux.cpp
index d900508ad9385ac6d07decf0b7b31b602893d2f3..7f59bc77f526b9265e01a4bfb09c850332ba553c 100644 (file)
--- a/lib/Driver/ToolChains/Linux.cpp
+++ b/lib/Driver/ToolChains/Linux.cpp
@@ -658,11 +658,11 @@ void Linux::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
   if (!DriverArgs.hasArg(options::OPT_nostdlibinc))
     addSystemInclude(DriverArgs, CC1Args, SysRoot + "/usr/local/include");
 
-  if (!DriverArgs.hasArg(options::OPT_nobuiltininc)) {
-    SmallString<128> P(D.ResourceDir);
-    llvm::sys::path::append(P, "include");
-    addSystemInclude(DriverArgs, CC1Args, P);
-  }
+  SmallString<128> ResourceDirInclude(D.ResourceDir);
+  llvm::sys::path::append(ResourceDirInclude, "include");
+  if (!DriverArgs.hasArg(options::OPT_nobuiltininc) &&
+      (!getTriple().isMusl() || DriverArgs.hasArg(options::OPT_nostdlibinc)))
+    addSystemInclude(DriverArgs, CC1Args, ResourceDirInclude);
 
   if (DriverArgs.hasArg(options::OPT_nostdlibinc))
     return;
@@ -860,6 +860,9 @@ void Linux::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
   addExternCSystemInclude(DriverArgs, CC1Args, SysRoot + "/include");
 
   addExternCSystemInclude(DriverArgs, CC1Args, SysRoot + "/usr/include");
+
+  if (!DriverArgs.hasArg(options::OPT_nobuiltininc) && getTriple().isMusl())
+    addSystemInclude(DriverArgs, CC1Args, ResourceDirInclude);
 }
 
 static std::string DetectLibcxxIncludePath(llvm::vfs::FileSystem &vfs,

diff --git a/test/Driver/linux-musl-header-search.cpp b/test/Driver/linux-musl-header-search.cpp
new file mode 100644 (file)
index 0000000..9fee036
--- /dev/null
+++ b/test/Driver/linux-musl-header-search.cpp
@@ -0,0 +1,39 @@
+// RUN: %clang -no-canonical-prefixes %s -### -fsyntax-only 2>&1 \
+// RUN:     -target x86_64-linux-musl -stdlib=libc++ \
+// RUN:     -ccc-install-dir %S/Inputs/basic_linux_tree/usr/bin \
+// RUN:     -resource-dir=%S/Inputs/resource_dir \
+// RUN:     --sysroot=%S/Inputs/basic_linux_libcxx_tree --gcc-toolchain= \
+// RUN:   | FileCheck --check-prefix=CHECK-X86-64-LIBCXX %s
+
+// RESOURCE_DIR/include comes after /usr/include on linux-musl.
+// This is different from a glibc-based distribution.
+// CHECK-X86-64-LIBCXX: "-resource-dir" "[[RESOURCE_DIR:[^"]+]]"
+// CHECK-X86-64-LIBCXX: "-isysroot" "[[SYSROOT:[^"]+]]"
+// CHECK-X86-64-LIBCXX: "-internal-isystem" "[[SYSROOT]]/usr/include/c++/v1"
+// CHECK-X86-64-LIBCXX: "-internal-isystem" "[[SYSROOT]]/usr/local/include"
+// CHECK-X86-64-LIBCXX: "-internal-externc-isystem" "[[SYSROOT]]/usr/include"
+// CHECK-X86-64-LIBCXX: "-internal-isystem" "[[RESOURCE_DIR]]{{/|\\\\}}include"
+
+// RUN: %clang -no-canonical-prefixes %s -### -fsyntax-only -nobuiltininc 2>&1 \
+// RUN:     -target x86_64-linux-musl \
+// RUN:     -ccc-install-dir %S/Inputs/basic_linux_tree/usr/bin \
+// RUN:     -resource-dir=%S/Inputs/resource_dir \
+// RUN:     --sysroot=%S/Inputs/basic_linux_libcxx_tree --gcc-toolchain= \
+// RUN:   | FileCheck --check-prefix=CHECK-NOBUILTININC %s
+
+// CHECK-NOBUILTININC: "-resource-dir" "[[RESOURCE_DIR:[^"]+]]"
+// CHECK-NOBUILTININC-NOT: "-internal-isystem" "[[RESOURCE_DIR]]{{/|\\\\}}include"
+
+// RUN: %clang -no-canonical-prefixes %s -### -fsyntax-only -nostdlibinc 2>&1 \
+// RUN:     -target x86_64-linux-musl \
+// RUN:     -ccc-install-dir %S/Inputs/basic_linux_tree/usr/bin \
+// RUN:     -resource-dir=%S/Inputs/resource_dir \
+// RUN:     --sysroot=%S/Inputs/basic_linux_libcxx_tree --gcc-toolchain= \
+// RUN:   | FileCheck --check-prefix=CHECK-NOSTDLIBINC %s
+
+// CHECK-NOSTDLIBINC: "-resource-dir" "[[RESOURCE_DIR:[^"]+]]"
+// CHECK-NOSTDLIBINC-NOT: "-internal-externc-isystem"
+// CHECK-NOSTDLIBINC-NOT: "-internal-isystem"
+// CHECK-NOSTDLIBINC: "-internal-isystem" "[[RESOURCE_DIR]]{{/|\\\\}}include"
+// CHECK-NOSTDLIBINC-NOT: "-internal-externc-isystem"
+// CHECK-NOSTDLIBINC-NOT: "-internal-isystem"