From @jkeenan

[The following is probably relevant to
https://rt-archive.perl.org/perl5/Ticket/Display.html?id=134371, but I'm filing it
separately as it may be a more general problem.]

When I select '-Dcc=clang++', as distinct from '-Dcc=clang', ./Configure
produces different results. This difference appears to be independent
of both operating system and other configuration options.

Suppose first that I configure blead
(7654aaa, Aug 17 2019) on Linux as follows​:

#####
sh ./Configure -de -Dusedevel -Dcc=clang
#####

... and then record the output of ./Configure in a file.

Next, suppose I clean the checkout then reconfigure and re-record the
output as follows​:

#####
sh ./Configure -de -Dusedevel -Dcc=clang++
#####

Here are the compiler versions​:

#####
$ clang --version; clang++ --version
clang version 6.0.0-1ubuntu2 (tags/RELEASE_600/final)
Target​: x86_64-pc-linux-gnu
Thread model​: posix
InstalledDir​: /usr/bin

clang version 6.0.0-1ubuntu2 (tags/RELEASE_600/final)
Target​: x86_64-pc-linux-gnu
Thread model​: posix
InstalledDir​: /usr/bin
#####

If I diff the two output files, I get several differences, but the
following appears to be most significant​:

#####
766c779,786
< I'll use gcvt to convert floats into a string.

gcvt oddity​: Expected 0.1, got 0.1
...But gcvt didn't work as I expected.
Trying sprintf...
sprintf() found.
sprintf oddity​: Expected 0.1, got 0.1
...But sprintf didn't work as I expected.
*** WHOA THERE!!! ***
None of ( gconvert gcvt sprintf) seemed to work properly. I'll use
sprintf.
#####

./Configure composes and runs a number of C programs on the fly as
probes. This file is typically named 'try.c'; the content of 'try.c' is
redefined several times during ./Configure. The relevant try.c starts
shortly after this comment at line 10370​: "​: Check how to convert floats
to strings." Within this C program we define a function called 'checkit()'.

#####
10429 int checkit(char *expect, char *got)
10430 {
10431 if (strcmp(expect, got)) {
10432 printf("%s oddity​: Expected %s, got %s\n",
10433 myname, expect, got);
10434 exit(1);
10435 }
10436 }
#####

Line 10432 above is the source of the surprising output above that I got
while configuring with clang++.

To answer one question in advance​: There is no leading or trailing
whitespace around '0.1'. I checked this by creating a branch in which I
put angle brackets around the last two instances of '%s' in the printf()
call above.

That implies that when running try.c, clang++ is calculating different
values for '*expect' and '*got' above line 10429. Moreover, clang++ is
getting different values both when calculating 'gcvt' and -- more
surprisingly -- when calculating 'sprintf'.

To answer another question in advance​: I don't get this difference when
compiling gcc versus g++.

Is this a bug in clang++? Or is it a bug in ./Configure?

Thank you very much.
Jim Keenan

From @jkeenan

Summary of my perl5 (revision 5 version 31 subversion 3) configuration​:
  Commit id​: 7654aaa
  Platform​:
  osname=linux
  osvers=4.15.0-58-generic
  archname=x86_64-linux
  uname='linux zareason 4.15.0-58-generic #64-ubuntu smp tue aug 6 11​:12​:41 utc 2019 x86_64 x86_64 x86_64 gnulinux '
  config_args='-de -Dusedevel -Dcc=clang++'
  hint=recommended
  useposix=true
  d_sigaction=define
  useithreads=undef
  usemultiplicity=undef
  use64bitint=define
  use64bitall=define
  uselongdouble=undef
  usemymalloc=n
  default_inc_excludes_dot=define
  bincompat5005=undef
  Compiler​:
  cc='clang++'
  ccflags ='-I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -D_FORTIFY_SOURCE=2'
  optimize='-O2'
  cppflags='-I/usr/local/include'
  ccversion=''
  gccversion='4.2.1 Compatible Clang 6.0.0 (tags/RELEASE_600/final)'
  gccosandvers=''
  intsize=4
  longsize=8
  ptrsize=8
  doublesize=8
  byteorder=12345678
  doublekind=3
  d_longlong=define
  longlongsize=8
  d_longdbl=define
  longdblsize=16
  longdblkind=3
  ivtype='long'
  ivsize=8
  nvtype='double'
  nvsize=8
  Off_t='off_t'
  lseeksize=8
  alignbytes=8
  prototype=define
  Linker and Libraries​:
  ld='clang++'
  ldflags =' -L/usr/local/lib'
  libpth=/usr/bin/../lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8 /usr/bin/../lib/gcc/x86_64-linux-gnu/8/../../../../include/x86_64-linux-gnu/c++/8 /usr/bin/../lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/backward /usr/local/lib /usr/include/x86_64-linux-gnu /usr/lib /lib/x86_64-linux-gnu /lib/../lib /usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib /lib64 /usr/lib64
  libs=-lpthread -lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lc
  perllibs=-lpthread -lnsl -ldl -lm -lcrypt -lutil -lc
  libc=libc-2.27.so
  so=so
  useshrplib=false
  libperl=libperl.a
  gnulibc_version='2.27'
  Dynamic Linking​:
  dlsrc=dl_dlopen.xs
  dlext=so
  d_dlsymun=undef
  ccdlflags='-Wl,-E'
  cccdlflags='-fPIC'
  lddlflags='-shared -O2 -L/usr/local/lib'

Characteristics of this binary (from libperl)​:
  Compile-time options​:
  HAS_TIMES
  PERLIO_LAYERS
  PERL_COPY_ON_WRITE
  PERL_DONT_CREATE_GVSV
  PERL_MALLOC_WRAP
  PERL_OP_PARENT
  PERL_PRESERVE_IVUV
  PERL_USE_DEVEL
  USE_64_BIT_ALL
  USE_64_BIT_INT
  USE_LARGE_FILES
  USE_LOCALE
  USE_LOCALE_COLLATE
  USE_LOCALE_CTYPE
  USE_LOCALE_NUMERIC
  USE_LOCALE_TIME
  USE_PERLIO
  USE_PERL_ATOF
  Built under linux
  Compiled at Aug 18 2019 11​:00​:35
  %ENV​:
  PERL2DIR="/home/jkeenan/gitwork/perl2"
  PERLBREW_HOME="/home/jkeenan/.perlbrew"
  PERLBREW_MANPATH="/home/jkeenan/perl5/perlbrew/perls/perl-5.30.0/man"
  PERLBREW_PATH="/home/jkeenan/perl5/perlbrew/bin​:/home/jkeenan/perl5/perlbrew/perls/perl-5.30.0/bin"
  PERLBREW_PERL="perl-5.30.0"
  PERLBREW_ROOT="/home/jkeenan/perl5/perlbrew"
  PERLBREW_SHELLRC_VERSION="0.84"
  PERLBREW_VERSION="0.84"
  PERL_WORKDIR="/home/jkeenan/gitwork/perl"
  @​INC​:
  lib
  /usr/local/lib/perl5/site_perl/5.31.3/x86_64-linux
  /usr/local/lib/perl5/site_perl/5.31.3
  /usr/local/lib/perl5/5.31.3/x86_64-linux
  /usr/local/lib/perl5/5.31.3

From @doughera88

On Sun, Aug 18, 2019 at 08​:04​:43AM -0700, James E Keenan (via RT) wrote​:

# New Ticket Created by James E Keenan
# Please include the string​: [perl #134375]
# in the subject line of all future correspondence about this issue.
# <URL​: https://rt-archive.perl.org/perl5/Ticket/Display.html?id=134375 >

[The following is probably relevant to
https://rt-archive.perl.org/perl5/Ticket/Display.html?id=134371, but I'm filing it
separately as it may be a more general problem.]

When I select '-Dcc=clang++', as distinct from '-Dcc=clang', ./Configure
produces different results. This difference appears to be independent
of both operating system and other configuration options.

Is this a bug in clang++? Or is it a bug in ./Configure?

It is a bug in Configure. The 'checkit()' program is declared to return
an integer, but actually returns nothing. (The return value is never used.)
This is undefined behavior in C++, but apparently not in C. See
  https://bugs.llvm.org/show_bug.cgi?id=43075
for a simple test case and explanation.

There are probably other such C vs. C++ bugs in Configure, including
possibly the detection of

  d_futimes
  d_lchown
  d_strtoll
  d_strtoul
  d_strtoull
  d_strtouq

I will leave this bug open as I work on those. Thank you for noticing
this issue in the first place!

--
  Andy Dougherty doughera@​lafayette.edu

The RT System itself - Status changed from 'new' to 'open'

From @doughera88

On Sun, Aug 18, 2019 at 08​:04​:43AM -0700, James E Keenan (via RT) wrote​:

# New Ticket Created by James E Keenan
# Please include the string​: [perl #134375]
# in the subject line of all future correspondence about this issue.
# <URL​: https://rt-archive.perl.org/perl5/Ticket/Display.html?id=134375 >
[The following is probably relevant to
https://rt-archive.perl.org/perl5/Ticket/Display.html?id=134371, but I'm filing it
separately as it may be a more general problem.]
When I select '-Dcc=clang++', as distinct from '-Dcc=clang', ./Configure
produces different results. This difference appears to be independent
of both operating system and other configuration options.

Is this a bug in clang++? Or is it a bug in ./Configure?

It is a bug in Configure. The 'checkit()' program is declared to return
an integer, but actually returns nothing. (The return value is never used.)
This is undefined behavior in C++, but apparently not in C. See
https://bugs.llvm.org/show_bug.cgi?id=43075
for a simple test case and explanation.

There are probably other such C vs. C++ bugs in Configure, including
possibly the detection of

d_futimes
d_lchown
d_strtoll
d_strtoul
d_strtoull
d_strtouq

I will leave this bug open as I work on those. Thank you for noticing
this issue in the first place!

--
Andy Dougherty doughera@​lafayette.edu

On Dec 13 2019, Andy D. submitted 5 patches to ./Configure to the p5p mailing list. I created the smoke-me/jkeenan/andyd/configure-20191214 branch off blead and in turn applied each patch, configured with clang++, and then diff-ed the config.sh and config.h against the preceding versions of those files. Below are diffs of those files before the 5 patches and after those 5 patches.

$ diff -w --ignore-matching-lines='Configuration time:' \
    --ignore-matching-lines='cf_time=' config.0.sh config.5.sh
347c347
< d_lchown='undef'
---
> d_lchown='define'
589c589
< d_strtoll='undef'
---
> d_strtoll='define'
591,593c591,593
< d_strtoul='undef'
< d_strtoull='undef'
< d_strtouq='undef'
---
> d_strtoul='define'
> d_strtoull='define'
> d_strtouq='define'

$ diff -w --ignore-matching-lines='Configuration time:' \
    --ignore-matching-lines='cf_time=' config.0.h config.5.h
939c939
< /*#define HAS_LCHOWN		/ **/
---
> #define HAS_LCHOWN		/**/
1957c1957
< /*#define HAS_STRTOUL	/ **/
---
> #define HAS_STRTOUL	/**/
3391c3391
< /*#define HAS_STRTOLL		/ **/
---
> #define HAS_STRTOLL		/**/
3403c3403
< /*#define HAS_STRTOULL		/ **/
---
> #define HAS_STRTOULL		/**/
3409c3409
< /*#define HAS_STRTOUQ		/ **/
---
> #define HAS_STRTOUQ		/**/

I then configured in the branch -- i.e., after applying the 5 patches -- with clang and then clang++ and compared those outputs.

$ diff -w --ignore-matching-lines='Configuration time:' \
    --ignore-matching-lines='cf_time=' clang-config.5.sh clang++-config.5.sh
17c17
< config_args='-des -Dusedevel -Dcc=clang'
---
> config_args='-des -Dusedevel -Dcc=clang++'
21c21
< config_arg3='-Dcc=clang'
---
> config_arg3='-Dcc=clang++'
63c63
< cc='clang'
---
> cc='clang++'
66c66
< ccflags='-fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -D_FORTIFY_SOURCE=2'
---
> ccflags='-I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -D_FORTIFY_SOURCE=2'
88c88
< cppflags='-fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include'
---
> cppflags='-I/usr/local/include'
91,92c91,92
< cpprun='clang  -E'
< cppstdin='clang  -E'
---
> cpprun='clang++  -E'
> cppstdin='clang++  -E'
127,135c127,135
< d_attribute_always_inline='define'
< d_attribute_deprecated='define'
< d_attribute_format='define'
< d_attribute_malloc='define'
< d_attribute_nonnull='define'
< d_attribute_noreturn='define'
< d_attribute_pure='define'
< d_attribute_unused='define'
< d_attribute_warn_unused_result='define'
---
> d_attribute_always_inline='undef'
> d_attribute_deprecated='undef'
> d_attribute_format='undef'
> d_attribute_malloc='undef'
> d_attribute_nonnull='undef'
> d_attribute_noreturn='undef'
> d_attribute_pure='undef'
> d_attribute_unused='undef'
> d_attribute_warn_unused_result='undef'
158c158
< d_cplusplus='undef'
---
> d_cplusplus='define'
221c221
< d_fds_bits='undef'
---
> d_fds_bits='define'
431c431
< d_off64_t='undef'
---
> d_off64_t='define'
447c447
< d_printf_format_null='define'
---
> d_printf_format_null='undef'
653,654c653,654
< db_hashtype='u_int32_t'
< db_prefixtype='size_t'
---
> db_hashtype='int'
> db_prefixtype='int'
688c688
< extern_C='extern'
---
> extern_C='extern "C"'
843c843
< incpth='/usr/local/include /usr/lib/llvm-6.0/lib/clang/6.0.0/include /usr/include/x86_64-linux-gnu /usr/include'
---
> incpth='/usr/bin/../lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8 /usr/bin/../lib/gcc/x86_64-linux-gnu/8/../../../../include/x86_64-linux-gnu/c++/8 /usr/bin/../lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/backward /usr/include/clang/6.0.0/include /usr/local/include /usr/include/x86_64-linux-gnu /usr/include'
881c881
< ld='clang'
---
> ld='clang++'
883,884c883,884
< lddlflags='-shared -O2 -L/usr/local/lib -fstack-protector-strong'
< ldflags=' -fstack-protector-strong -L/usr/local/lib'
---
> lddlflags='-shared -O2 -L/usr/local/lib'
> ldflags=' -L/usr/local/lib'
891c891
< libpth='/usr/local/lib /usr/lib/llvm-6.0/lib/clang/6.0.0/lib /usr/include/x86_64-linux-gnu /usr/lib /lib/x86_64-linux-gnu /lib/../lib /usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib /lib64 /usr/lib64'
---
> libpth='/usr/bin/../lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8 /usr/bin/../lib/gcc/x86_64-linux-gnu/8/../../../../include/x86_64-linux-gnu/c++/8 /usr/bin/../lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/backward /usr/local/lib /usr/include/x86_64-linux-gnu /usr/lib /lib/x86_64-linux-gnu /lib/../lib /usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib /lib64 /usr/lib64'
896c896
< libspath=' /usr/local/lib /usr/lib/llvm-6.0/lib/clang/6.0.0/lib /usr/include/x86_64-linux-gnu /usr/lib /lib/x86_64-linux-gnu /lib/../lib /usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib /lib64 /usr/lib64'
---
> libspath=' /usr/bin/../lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8 /usr/bin/../lib/gcc/x86_64-linux-gnu/8/../../../../include/x86_64-linux-gnu/c++/8 /usr/bin/../lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/backward /usr/local/lib /usr/include/x86_64-linux-gnu /usr/lib /lib/x86_64-linux-gnu /lib/../lib /usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib /lib64 /usr/lib64'
1004c1004
< ranlib=':'
---
> ranlib='/usr/bin/ranlib'

$ diff -w --ignore-matching-lines='Configuration time:' \
    --ignore-matching-lines='cf_time=' clang-config.5.h clang++-config.5.h
1420c1420
< #define CPPSTDIN "clang  -E"
---
> #define CPPSTDIN "clang++  -E"
1422c1422
< #define CPPRUN "clang  -E"
---
> #define CPPRUN "clang++  -E"
1459,1468c1459,1468
< #define HASATTRIBUTE_DEPRECATED	/**/
< #define HASATTRIBUTE_FORMAT	/**/
< #define PRINTF_FORMAT_NULL_OK	/**/
< #define HASATTRIBUTE_NORETURN	/**/
< #define HASATTRIBUTE_MALLOC	/**/
< #define HASATTRIBUTE_NONNULL	/**/
< #define HASATTRIBUTE_PURE	/**/
< #define HASATTRIBUTE_UNUSED	/**/
< #define HASATTRIBUTE_WARN_UNUSED_RESULT	/**/
< #define HASATTRIBUTE_ALWAYS_INLINE	/**/
---
> /*#define HASATTRIBUTE_DEPRECATED	/ **/
> /*#define HASATTRIBUTE_FORMAT	/ **/
> /*#define PRINTF_FORMAT_NULL_OK	/ **/
> /*#define HASATTRIBUTE_NORETURN	/ **/
> /*#define HASATTRIBUTE_MALLOC	/ **/
> /*#define HASATTRIBUTE_NONNULL	/ **/
> /*#define HASATTRIBUTE_PURE	/ **/
> /*#define HASATTRIBUTE_UNUSED	/ **/
> /*#define HASATTRIBUTE_WARN_UNUSED_RESULT	/ **/
> /*#define HASATTRIBUTE_ALWAYS_INLINE	/ **/
2373c2373
< /*#define USE_CPLUSPLUS		/ **/
---
> #define USE_CPLUSPLUS		/**/
3113c3113
< /*#define	HAS_OFF64_T		/ **/
---
> #define	HAS_OFF64_T		/**/
3618,3619c3618,3619
< #define DB_Hash_t	u_int32_t		/**/
< #define DB_Prefix_t	size_t		/**/
---
> #define DB_Hash_t	int		/**/
> #define DB_Prefix_t	int		/**/

Thank you very much.
Jim Keenan

### From @doughera88
On Sun, Aug 18, 2019 at 08​:04​:43AM -0700, James E Keenan (via RT) wrote​:

# New Ticket Created by James E Keenan
# Please include the string​: [perl #134375]
# in the subject line of all future correspondence about this issue.
# <URL​: https://rt-archive.perl.org/perl5/Ticket/Display.html?id=134375 >
[The following is probably relevant to
https://rt-archive.perl.org/perl5/Ticket/Display.html?id=134371, but I'm filing it
separately as it may be a more general problem.]
When I select '-Dcc=clang++', as distinct from '-Dcc=clang', ./Configure
produces different results. This difference appears to be independent
of both operating system and other configuration options.

Is this a bug in clang++? Or is it a bug in ./Configure?

It is a bug in Configure. The 'checkit()' program is declared to return
an integer, but actually returns nothing. (The return value is never used.)
This is undefined behavior in C++, but apparently not in C. See
https://bugs.llvm.org/show_bug.cgi?id=43075
for a simple test case and explanation.
There are probably other such C vs. C++ bugs in Configure, including
possibly the detection of
d_futimes
d_lchown
d_strtoll
d_strtoul
d_strtoull
d_strtouq
I will leave this bug open as I work on those. Thank you for noticing
this issue in the first place!

Andy Dougherty doughera@​lafayette.edu

On Dec 13 2019, Andy D. submitted 5 patches to ./Configure to the p5p mailing list. I created the smoke-me/jkeenan/andyd/configure-20191214 branch off blead and in turn applied each patch, configured with clang++, and then diff-ed the config.sh and config.h against the preceding versions of those files. Below are diffs of those files before the 5 patches and after those 5 patches.

[snip]

I then configured in the branch -- i.e., after applying the 5 patches -- with clang and then clang++ and compared those outputs.

$ diff -w --ignore-matching-lines='Configuration time:' \
    --ignore-matching-lines='cf_time=' clang-config.5.sh clang++-config.5.sh
17c17
< config_args='-des -Dusedevel -Dcc=clang'
---
> config_args='-des -Dusedevel -Dcc=clang++'
21c21
< config_arg3='-Dcc=clang'
---
> config_arg3='-Dcc=clang++'
63c63
< cc='clang'
---
> cc='clang++'
66c66
< ccflags='-fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -D_FORTIFY_SOURCE=2'
---
> ccflags='-I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -D_FORTIFY_SOURCE=2'
88c88
< cppflags='-fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include'
---
> cppflags='-I/usr/local/include'
91,92c91,92
< cpprun='clang  -E'
< cppstdin='clang  -E'
---
> cpprun='clang++  -E'
> cppstdin='clang++  -E'
127,135c127,135
< d_attribute_always_inline='define'
< d_attribute_deprecated='define'
< d_attribute_format='define'
< d_attribute_malloc='define'
< d_attribute_nonnull='define'
< d_attribute_noreturn='define'
< d_attribute_pure='define'
< d_attribute_unused='define'
< d_attribute_warn_unused_result='define'
---
> d_attribute_always_inline='undef'
> d_attribute_deprecated='undef'
> d_attribute_format='undef'
> d_attribute_malloc='undef'
> d_attribute_nonnull='undef'
> d_attribute_noreturn='undef'
> d_attribute_pure='undef'
> d_attribute_unused='undef'
> d_attribute_warn_unused_result='undef'
158c158
< d_cplusplus='undef'
---
> d_cplusplus='define'
221c221
< d_fds_bits='undef'
---
> d_fds_bits='define'
431c431
< d_off64_t='undef'
---
> d_off64_t='define'
447c447
< d_printf_format_null='define'
---
> d_printf_format_null='undef'
653,654c653,654
< db_hashtype='u_int32_t'
< db_prefixtype='size_t'
---
> db_hashtype='int'
> db_prefixtype='int'
688c688
< extern_C='extern'
---
> extern_C='extern "C"'
843c843
< incpth='/usr/local/include /usr/lib/llvm-6.0/lib/clang/6.0.0/include /usr/include/x86_64-linux-gnu /usr/include'
---
> incpth='/usr/bin/../lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8 /usr/bin/../lib/gcc/x86_64-linux-gnu/8/../../../../include/x86_64-linux-gnu/c++/8 /usr/bin/../lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/backward /usr/include/clang/6.0.0/include /usr/local/include /usr/include/x86_64-linux-gnu /usr/include'
881c881
< ld='clang'
---
> ld='clang++'
883,884c883,884
< lddlflags='-shared -O2 -L/usr/local/lib -fstack-protector-strong'
< ldflags=' -fstack-protector-strong -L/usr/local/lib'
---
> lddlflags='-shared -O2 -L/usr/local/lib'
> ldflags=' -L/usr/local/lib'
891c891
< libpth='/usr/local/lib /usr/lib/llvm-6.0/lib/clang/6.0.0/lib /usr/include/x86_64-linux-gnu /usr/lib /lib/x86_64-linux-gnu /lib/../lib /usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib /lib64 /usr/lib64'
---
> libpth='/usr/bin/../lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8 /usr/bin/../lib/gcc/x86_64-linux-gnu/8/../../../../include/x86_64-linux-gnu/c++/8 /usr/bin/../lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/backward /usr/local/lib /usr/include/x86_64-linux-gnu /usr/lib /lib/x86_64-linux-gnu /lib/../lib /usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib /lib64 /usr/lib64'
896c896
< libspath=' /usr/local/lib /usr/lib/llvm-6.0/lib/clang/6.0.0/lib /usr/include/x86_64-linux-gnu /usr/lib /lib/x86_64-linux-gnu /lib/../lib /usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib /lib64 /usr/lib64'
---
> libspath=' /usr/bin/../lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8 /usr/bin/../lib/gcc/x86_64-linux-gnu/8/../../../../include/x86_64-linux-gnu/c++/8 /usr/bin/../lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/backward /usr/local/lib /usr/include/x86_64-linux-gnu /usr/lib /lib/x86_64-linux-gnu /lib/../lib /usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib /lib64 /usr/lib64'
1004c1004
< ranlib=':'
---
> ranlib='/usr/bin/ranlib'

$ diff -w --ignore-matching-lines='Configuration time:' \
    --ignore-matching-lines='cf_time=' clang-config.5.h clang++-config.5.h
1420c1420
< #define CPPSTDIN "clang  -E"
---
> #define CPPSTDIN "clang++  -E"
1422c1422
< #define CPPRUN "clang  -E"
---
> #define CPPRUN "clang++  -E"
1459,1468c1459,1468
< #define HASATTRIBUTE_DEPRECATED	/**/
< #define HASATTRIBUTE_FORMAT	/**/
< #define PRINTF_FORMAT_NULL_OK	/**/
< #define HASATTRIBUTE_NORETURN	/**/
< #define HASATTRIBUTE_MALLOC	/**/
< #define HASATTRIBUTE_NONNULL	/**/
< #define HASATTRIBUTE_PURE	/**/
< #define HASATTRIBUTE_UNUSED	/**/
< #define HASATTRIBUTE_WARN_UNUSED_RESULT	/**/
< #define HASATTRIBUTE_ALWAYS_INLINE	/**/
---
> /*#define HASATTRIBUTE_DEPRECATED	/ **/
> /*#define HASATTRIBUTE_FORMAT	/ **/
> /*#define PRINTF_FORMAT_NULL_OK	/ **/
> /*#define HASATTRIBUTE_NORETURN	/ **/
> /*#define HASATTRIBUTE_MALLOC	/ **/
> /*#define HASATTRIBUTE_NONNULL	/ **/
> /*#define HASATTRIBUTE_PURE	/ **/
> /*#define HASATTRIBUTE_UNUSED	/ **/
> /*#define HASATTRIBUTE_WARN_UNUSED_RESULT	/ **/
> /*#define HASATTRIBUTE_ALWAYS_INLINE	/ **/
2373c2373
< /*#define USE_CPLUSPLUS		/ **/
---
> #define USE_CPLUSPLUS		/**/
3113c3113
< /*#define	HAS_OFF64_T		/ **/
---
> #define	HAS_OFF64_T		/**/
3618,3619c3618,3619
< #define DB_Hash_t	u_int32_t		/**/
< #define DB_Prefix_t	size_t		/**/
---
> #define DB_Hash_t	int		/**/
> #define DB_Prefix_t	int		/**/

Andy (@doughera88), are these differences between the results of configuration with clang and clang++, respectively, those that you would expect to remain after applying your five patches (as, e.g., in the smoke-me/jkeenan/andyd/configure-20191214 branch)?

If so, then I think we should apply those to blead and then (@Tux) apply them to metaconfig. Smoke-test results are satisfactory (i.e., no new failures caused by these patches).

Another way of asking the same question: Can you list those problematic configuration differences that these patches resolve and those that you are still working on?

Thank you very much.
Jim Keenan

[snip]
I've applied the patches to blead. I am not currently working on any other related issues, so this ticket can be closed. Thank you for following up on this,
…
-- Andy Dougherty doughera@lafayette.edu

Thanks. I've taken the ticket for purpose of closing it after watching smoke test results.

@Tux , @arc, @khwilliamson Can you apply these to metaconfig?

Thank you very much.
Jim Keenan

Changes needed in blead were pushed by @doughera88 on Dec 29 2019. Closing ticket. Thank you very much.