[libcxx-commits] [PATCH] D116498: [libcxx] Use Fuchsia-native CPRNG for std::random_device

[Petr Hosek via Phabricator via libcxx-commits]

phosek added a comment.

LGTM



================
Comment at: libcxx/src/random.cpp:188
+  // statically linking libc++.
+#  pragma comment(lib, "zircon")
+
----------------
ldionne wrote:
> mcgrathr wrote:
> > ldionne wrote:
> > > This pragma is magic. It leaves a breadcrumb in the `.o` and the linker will pick it up automatically?
> > > 
> > > On what platforms does this work?
> > Correct.  The pragma syntax comes from MSVC and works there and in Clang on PE-COFF and ELF formats.  The ELF linker magic it uses is only supported by lld last I checked (it emits an extra non-allocated section that other linkers would just ignore).  For Fuchsia, we are fine assuming that current Clang and LLD are the only tools used.
> > 
> This is pretty awesome, we could use that for mach-o as well.
We already use it elsewhere in libc++, for example https://github.com/llvm/llvm-project/blob/3064dd8ccffc561e0f01cfa930b9a481d90e7f4f/libcxx/src/chrono.cpp#L52, https://github.com/llvm/llvm-project/blob/3064dd8ccffc561e0f01cfa930b9a481d90e7f4f/libcxx/src/thread.cpp#L31 or https://github.com/llvm/llvm-project/blob/3064dd8ccffc561e0f01cfa930b9a481d90e7f4f/libcxx/include/__config#L1375.


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