<html>
<head>
<base href="https://bugs.llvm.org/">
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Android NDK Clang driver can't find libc++ headers"
href="https://bugs.llvm.org/show_bug.cgi?id=46213">46213</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Android NDK Clang driver can't find libc++ headers
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>Driver
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>rprichard@google.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org, neeilans@live.com, richard-llvm@metafoo.co.uk
</td>
</tr></table>
<p>
<div>
<pre>If no --sysroot flag is passed to the driver, then the Android NDK Clang driver
is unable to find the libc++ headers. It can still find the rest of the headers
from the NDK sysroot, though, because Linux::AddClangSystemIncludeArgs uses
computeSysRoot().
I suspect <a href="https://reviews.llvm.org/D69758">https://reviews.llvm.org/D69758</a> broke things.
Previously, Linux::addLibCxxIncludePaths used Linux::computeSysRoot(), which
has this code:
std::string Linux::computeSysRoot() const {
if (!getDriver().SysRoot.empty())
return getDriver().SysRoot;
if (getTriple().isAndroid()) {
// Android toolchains typically include a sysroot at ../sysroot
relative to
// the clang binary.
const StringRef ClangDir = getDriver().getInstalledDir();
std::string AndroidSysRootPath = (ClangDir + "/../sysroot").str();
if (getVFS().exists(AndroidSysRootPath))
return AndroidSysRootPath;
}
The Generic_GCC::addLibCxxIncludePaths function, though, just uses
getDriver().SysRoot, which is typically an empty string.
If I *do* pass --sysroot to Clang, then it is able to find the libc++ headers
in the NDK sysroot.
FWIW, the Android team at Google doesn't care about the -stdlib=libstdc++ case,
so we don't care about the Android-specific stuff in
Linux::addLibStdCxxIncludePaths:
// Android standalone toolchain has C++ headers in yet another place.
LibDir.str() + "/../" + TripleStr.str() + "/include/c++/" + Version.Text,
There are various computeSysRoot functions in classes derived from ToolChain.
They all use the getDriver().SysRoot() if it's non-empty, then have some logic
for computing a default sysroot.
One possible fix:
- Add a non-virtual ToolChain::computeSysRoot.
- Add a virtual ToolChain::computeDefaultSysRoot that returns std::string().
- Override computeDefaultSysRoot as appropriate.</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>