[llvm] 547c551 - [gn build] Try to fix build on linux after std=c++17 switch

[Nico Weber via llvm-commits]

Author: Nico Weber
Date: 2022-08-06T08:34:24-04:00
New Revision: 547c551925c8f4dd979ba5cf16c857091a80254b

URL: https://github.com/llvm/llvm-project/commit/547c551925c8f4dd979ba5cf16c857091a80254b
DIFF: https://github.com/llvm/llvm-project/commit/547c551925c8f4dd979ba5cf16c857091a80254b.diff

LOG: [gn build] Try to fix build on linux after std=c++17 switch

glibc annotates `process_vm_readv` with `__THROW`.
lldb/include/lldb/Host/linux/Uio.h and
lldb/source/Host/linux/LibcGlue.cpp don't.

Having a mismatch causes an error with c++17:

    ../../lldb/source/Host/linux/LibcGlue.cpp:18:9:
        error: 'process_vm_readv' is missing exception specification 'throw()'
    ssize_t process_vm_readv(::pid_t pid, const struct iovec *local_iov,
            ^
    ../../lldb/include/lldb/Host/linux/Uio.h:18:9:
        note: previous declaration is here
    ssize_t process_vm_readv(::pid_t pid, const struct iovec *local_iov,
            ^

The diagnostic is a bit misleading, since the previous declaration
in the sysroot (in usr/include/x76_64-linux-gnu/bits/uio-ext.h) is
what has the `__THROW`.

In the cmake build, cmake sets `HAVE_PROCESS_VM_READV` correctly based
on header probing.

In the GN build, just set it to 1 unconditionally on linux. If that
turns out to not be good enough everywhere, we'll have to add a GN arg
for this.

(I'm also setting it to 1 on Android. I'm not sure if that's correct --
but we don't build lldb for Android anyways.)

Added: 
    

Modified: 
    llvm/utils/gn/secondary/lldb/include/lldb/Host/BUILD.gn

Removed: 
    


################################################################################
diff  --git a/llvm/utils/gn/secondary/lldb/include/lldb/Host/BUILD.gn b/llvm/utils/gn/secondary/lldb/include/lldb/Host/BUILD.gn
index 7e9c03c84e784..090580f52be6e 100644
--- a/llvm/utils/gn/secondary/lldb/include/lldb/Host/BUILD.gn
+++ b/llvm/utils/gn/secondary/lldb/include/lldb/Host/BUILD.gn
@@ -62,8 +62,14 @@ write_cmake_config("Config") {
   }
 
   if (current_os == "linux" || current_os == "android") {
-    values += [ "HAVE_PPOLL=1" ]
+    values += [
+      "HAVE_PPOLL=1",
+      "HAVE_PROCESS_VM_READV=1",
+    ]
   } else {
-    values += [ "HAVE_PPOLL=" ]
+    values += [
+      "HAVE_PPOLL=",
+      "HAVE_PROCESS_VM_READV=",
+    ]
   }
 }