Hi,

Internally (in XS,xs), JSON-XS uses Gconvert(): 
Gconvert (SvNVX (sv), NV_DIG, 0, enc->cur);

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But Gconvert() doesn't DWIM when nvtype is __float128, so I've altered that code to: 
#ifdef USE_QUADMATH
quadmath_snprintf(enc->cur, NV_DIG, "%.33Qg", SvNVX (sv)); /* NV_DIG i
+s 33 for quadmath builds */
#else
Gconvert (SvNVX (sv), NV_DIG, 0, enc->cur);
#endif

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I've chosen "33" (== the value of NV_DIG on quadmath builds) because Gconvert uses NV_DIG for both "double" builds of perl (where NV_DIG is 15) and "long double" builds of perl (where NV_DIG is 18).

It seems to work pretty well - but there's one JSON-XS-4.03 test that fails: 
t/11_pc_expo.t .......... 1/8
#   Failed test 'digit 1.01e+30'
#   at t/11_pc_expo.t line 35.
#                   '[1010000000000000000000000000000]'
#     doesn't match '(?^:\[1.01[Ee]\+0?30\])'
# Looks like you failed 1 test of 8.

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Before I investigate that test failure, I just want to check that NV_DIG (33) is the correct value to be specifying in the "%Qg" formatting ??
If I alter that value of 33 to 30 (or less), then all tests pass ... but I know very little about json, or what it expects, or what is expected of it.

Any assistance would be much appreciated.

Cheers,
Rob

In reply to JSON-XS on quadmath builds of perl by syphilis

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