Difficulties compiling: clang (not clang++) to precompile c++ headers; various compiler warnings (treated as errors)

[Jiri Daněk]

I attempted compilation of jdk-tsan with both gcc9 and clang_8. With either
compiler, I had to add additional options to configure, otherwise
compilation would fail. I thought I'll mention it here.

# Gcc 9

I had to do

bash configure --disable-warnings-as-errors

otherwise I'd have errors like

In file included from
> /nix/store/bniand9afisrgrsfi7kr093334iv3ibv-glibc-2.27-dev/include/stdio.h:862,
>                  from
> /home/jdanek/repos/jdk-tsan/src/hotspot/share/adlc/adlc.hpp:35,
>                  from
> /home/jdanek/repos/jdk-tsan/src/hotspot/share/adlc/adlparse.cpp:27:
> In function 'int fprintf(FILE*, const char*, ...)',
>     inlined from 'FormatRule* ADLParser::template_parse()' at
> /home/jdanek/repos/jdk-tsan/src/hotspot/share/adlc/adlparse.cpp:4080:34:
> /nix/store/bniand9afisrgrsfi7kr093334iv3ibv-glibc-2.27-dev/include/bits/stdio2.h:97:24:
> error: '%s' directive argument is null [-Werror=format-overflow=]
>    97 |   return __fprintf_chk (__stream, __USE_FORTIFY_LEVEL - 1, __fmt,
>       |          ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>    98 |    __va_arg_pack ());
>       |    ~~~~~~~~~~~~~~~~~
>

# Clang 8

I had to do

bash configure --with-toolchain-type=clang --disable-precompiled-headers
--disable-warnings-as-errors

without --disable-precompiled-headers, make would try to compile headers
with clang, instead of clang++, and my clang would not find c++ headers

$ LOG=trace make
> [...]
>
/nix/store/ki0cb2q9bib66zwjldfk6dkp9apkmgph-clang-wrapper-8.0.0/bin/clang
-D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -D__STDC_CONSTANT_MACROS
-D_GNU_SOURCE -pipe -fno-rtti -fno-exceptions -fvisibility=hidden
-fno-strict-aliasing -fno-omit-frame-pointer -flimit-debug-info
-mno-omit-leaf-frame-pointer -mstack-alignment=16
-DSUPPORTS_CLOCK_MONOTONIC -DLINUX -Wall -Wextra -Wformat=2 -Wpointer-arith
-Wsign-compare -Wreorder -Wunused-function -Wundef -Wunused-value
-Woverloaded-virtual -fPIC -DVM_LITTLE_ENDIAN -D_LP64=1 -m64 -DPRODUCT
-DTARGET_ARCH_x86 -DINCLUDE_SUFFIX_OS=_linux -DINCLUDE_SUFFIX_CPU=_x86
-DINCLUDE_SUFFIX_COMPILER=_gcc -DTARGET_COMPILER_gcc -DAMD64
'-DHOTSPOT_LIB_ARCH="amd64"' -DCOMPILER1 -DCOMPILER2
-DSUPPORT_BARRIER_ON_PRIMITIVES -DSUPPORT_NOT_TO_SPACE_INVARIANT
-I/home/jdanek/repos/jdk-tsan/build/linux-x86_64-server-release/hotspot/variant-server/gensrc/adfiles
-I/home/jdanek/repos/jdk-tsan/src/hotspot/share
-I/home/jdanek/repos/jdk-tsan/src/hotspot/os/linux
-I/home/jdanek/repos/jdk-tsan/src/hotspot/os/posix
-I/home/jdanek/repos/jdk-tsan/src/hotspot/cpu/x86
-I/home/jdanek/repos/jdk-tsan/src/hotspot/os_cpu/linux_x86
-I/home/jdanek/repos/jdk-tsan/build/linux-x86_64-server-release/hotspot/variant-server/gensrc
-I/home/jdanek/repos/jdk-tsan/src/hotspot/share/precompiled
-I/home/jdanek/repos/jdk-tsan/src/hotspot/share/include
-I/home/jdanek/repos/jdk-tsan/src/hotspot/os/posix/include
-I/home/jdanek/repos/jdk-tsan/build/linux-x86_64-server-release/support/modules_include/java.base
-I/home/jdanek/repos/jdk-tsan/build/linux-x86_64-server-release/support/modules_include/java.base/linux
-I/home/jdanek/repos/jdk-tsan/src/java.base/share/native/libjimage -m64 -g
-Wno-unused-parameter -Wno-unused -Wno-tautological-compare
-Wno-undefined-var-template -Wno-sometimes-uninitialized
-Wno-unknown-pragmas -Wno-delete-non-virtual-dtor -Wno-missing-braces
-Wno-char-subscripts -Wno-ignored-qualifiers
-Wno-missing-field-initializers -Wno-mismatched-tags -Werror -O3 -x
c++-header -c -MMD -MF
/home/jdanek/repos/jdk-tsan/build/linux-x86_64-server-release/hotspot/variant-server/libjvm/objs/precompiled/precompiled.hpp.pch.d
/home/jdanek/repos/jdk-tsan/src/hotspot/share/precompiled/precompiled.hpp
-o
/home/jdanek/repos/jdk-tsan/build/linux-x86_64-server-release/hotspot/variant-server/libjvm/objs/precompiled/precompiled.hpp.pch
In file included from
/home/jdanek/repos/jdk-tsan/src/hotspot/share/precompiled/precompiled.hpp:34:
In file included from
/home/jdanek/repos/jdk-tsan/src/hotspot/share/classfile/classLoaderData.hpp:28:
/home/jdanek/repos/jdk-tsan/src/hotspot/share/memory/allocation.hpp:32:10:
fatal error: 'new' file not found
#include <new>
         ^~~~~
1 error generated.


when I rerun the command with clang++, it passed without error.

Next, --disable-warnings-as-errors was needed because of warnings like this

>
> /home/jdanek/repos/jdk-tsan/test/hotspot/gtest/classfile/test_symbolTable.cpp:62:6:
> error: explicitly assigning value of variable of type 'TempNewSymbol' to
> itself [-Werror,-Wself-assign-overloaded]
>   s1 = s1; // self assignment
>   ~~ ^ ~~
> 1 error generated.
>
> /home/jdanek/repos/jdk-tsan/src/java.smartcardio/share/native/libj2pcsc/pcsc.c:48:9:
> warning: 'dprintf' macro redefined [-Wmacro-redefined]
> #define dprintf(s)
>         ^
> /nix/store/bniand9afisrgrsfi7kr093334iv3ibv-glibc-2.27-dev/include/bits/stdio2.h:145:12:
> note: previous definition is here
> #   define dprintf(fd, ...) \
>            ^
> Creating support/modules_cmds/jdk.aot/jaotc from 1 file(s)
>

and later I saw also this

clang-8: warning: argument unused during compilation: '-D
> _FORTIFY_SOURCE=2' [-Wunused-command-line-argument]
> clang-8: warning: argument unused during compilation:
> '-fstack-protector-strong' [-Wunused-command-line-argument]
> clang-8: warning: argument unused during compilation: '--param
> ssp-buffer-size=4' [-Wunused-command-line-argument]
> clang-8: warning: argument unused during compilation:
> '-fno-strict-overflow' [-Wunused-command-line-argument]
> clang-8: warning: argument unused during compilation: '-idirafter
> /nix/store/bniand9afisrgrsfi7kr093334iv3ibv-glibc-2.27-dev/include'
> [-Wunused-command-line-argument]
> clang-8: warning: argument unused during compilation: '-isystem
> /nix/store/1s2f1fhb63kv01s0mbjrs7sps0lvc5qi-libc++-8.0.0/include'
> [-Wunused-command-line-argument]
>

Thanks,
-- 
Mit freundlichen Grüßen / Kind regards
Jiri Daněk