[clang] [clang][Driver] Fix libc++ include path on NetBSD (PR #212716)

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llvmorg-github-actions[bot] wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-driver

Author: Rainer Orth (rorth)

<details>
<summary>Changes</summary>

`clang++` defaults to `-stdlib=libc++` on NetBSD.  When building with both 
`clang` and `libcxx` included, the freshly built `clang++` fails to find 
`&lt;__config_site&gt;`:

```
In file included from /usr/include/strings.h:68:
In file included from bin/../include/c++/v1/string.h:57:
bin/../include/c++/v1/__config:13:10: fatal
error: '__config_site' file not found
   13 | #include &lt;__config_site&gt;
      |          ^~~~~~~~~~~~~~~
```

The file is present in `include/&lt;triplet&gt;/c++/v1`, but that isn't 
searched by default.  NetBSD has its own version of addLibCxxIncludePaths which 
misses that directory.

Rather than replicating yet another part of the generic version in `Gnu.cpp`, 
this patch just calls `Generic_GCC::addLibCxxIncludePaths` from there.  It 
keeps to also include `/usr/include/c++`, although this directory only contains 
empty directories in my installation.

Tested on `amd64-pc-netbsd10.1`.

I know that this patch also needs testcases (currently there are none that are 
affected by this change), but I'd like to get this into the system first to 
check that the approach is sound.

---
Full diff: https://github.com/llvm/llvm-project/pull/212716.diff


1 Files Affected:

- (modified) clang/lib/Driver/ToolChains/NetBSD.cpp (+8-16) 


``````````diff
diff --git a/clang/lib/Driver/ToolChains/NetBSD.cpp 
b/clang/lib/Driver/ToolChains/NetBSD.cpp
index 31a5723c17c2f..186a34143da37 100644
--- a/clang/lib/Driver/ToolChains/NetBSD.cpp
+++ b/clang/lib/Driver/ToolChains/NetBSD.cpp
@@ -6,6 +6,7 @@
 //
 
//===----------------------------------------------------------------------===//
 
+#include "Gnu.h"
 #include "NetBSD.h"
 #include "Arch/ARM.h"
 #include "Arch/Mips.h"
@@ -497,23 +498,14 @@ void NetBSD::AddClangSystemIncludeArgs(
 
 void NetBSD::addLibCxxIncludePaths(const llvm::opt::ArgList &DriverArgs,
                                    llvm::opt::ArgStringList &CC1Args) const {
-  const std::string Candidates[] = {
-    // directory relative to build tree
-    concat(getDriver().Dir, "/../include/c++/v1"),
-    // system install with full upstream path
-    concat(getDriver().SysRoot, "/usr/include/c++/v1"),
-    // system install from src
-    concat(getDriver().SysRoot, "/usr/include/c++"),
-  };
-
-  for (const auto &IncludePath : Candidates) {
-    if (!getVFS().exists(IncludePath + "/__config"))
-      continue;
-
-    // Use the first candidate that looks valid.
+  Generic_GCC::addLibCxxIncludePaths(DriverArgs, CC1Args);
+
+  // system install from src
+  const std::string IncludePath =
+      concat(getDriver().SysRoot, "/usr/include/c++");
+
+  if (getVFS().exists(IncludePath + "/__config"))
     addSystemInclude(DriverArgs, CC1Args, IncludePath);
-    return;
-  }
 }
 
 void NetBSD::addLibStdCxxIncludePaths(const llvm::opt::ArgList &DriverArgs,

``````````

</details>


https://github.com/llvm/llvm-project/pull/212716
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