I've built 5.10 on Solaris 10, and make test fails on t/base/num.t thusly: 
1..50
ok 1
ok 2
ok 3
ok 4
not ok 5 # 0.100000000000000005551115123125783
not ok 6 # -0.100000000000000005551115123125783
not ok 7 # 0.100000000000000005551115123125783
not ok 8 # -0.100000000000000005551115123125783
not ok 9 # 10.0099999999999997868371792719699
ok 10
ok 11

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The tests look like this: 
$a = 0.1; "$a";
print $a eq "0.1"     ? "ok 5\n"  : "not ok 5 # $a\n";

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I configured this with -Duse64bitall and added the -m64 and -mcpu=v9 flags to the compile and link commands. For chuckles I installed anyway and tried to update CPAN and all the version checking failed with things like: 
#   Failed test '  <SOFTPKG>'
#   at t/basic.t line 83.
#                   '<SOFTPKG NAME="Big-Dummy" VERSION="0.010000000000
+0000002081668171172169">

[...]

#     doesn't match '(?m-xis:^<SOFTPKG NAME="Big-Dummy" VERSION="0.01"
+>)'

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If I build it as a 32-bit app, I get: 
./perl -e "$a=> perl -e '$a = 0.1; print "$a\n";' 
0.1

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But as a 64-bit app, I get: 
> ./perl -e '$a = 0.1; print "$a\n";' 
0.100000000000000005551115123125783

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I've done a lot of trial-and-error with the config flags and settings, but no luck so far. I've googled and googled till my googler was sore. Can you think of something I haven't before? Anything remotely helpful will be appreciated, lauded, and extolled beyond reasonable measure.

In reply to 64-bit build fails numeric tests by eshafto

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