Fix numeric_power() when the exponent is INT_MIN.
In power_var_int(), the computation of the number of significant
digits to use in the computation used log(Abs(exp)), which isn't safe
because Abs(exp) returns INT_MIN when exp is INT_MIN. Use fabs()
instead of Abs(), so that the exponent is cast to a double before the
absolute value is taken.
Back-patch to 9.6, where this was introduced (by 7d9a4737c2
).
Discussion: https://postgr.es/m/CAEZATCVd6pMkz=BrZEgBKyqqJrt2xghr=fNc8+Z=5xC6cgWrWA@mail.gmail.com
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@ -9370,7 +9370,7 @@ power_var_int(const NumericVar *base, int exp, NumericVar *result, int rscale)
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* to around log10(abs(exp)) digits, so work with this many extra digits
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* of precision (plus a few more for good measure).
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*/
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sig_digits += (int) log(Abs(exp)) + 8;
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sig_digits += (int) log(fabs(exp)) + 8;
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/*
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* Now we can proceed with the multiplications.
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@ -1674,6 +1674,12 @@ select 0.12 ^ (-20);
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2608405330458882702.5529619561355838
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(1 row)
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select 1.000000000123 ^ (-2147483648);
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?column?
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--------------------
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0.7678656556403084
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(1 row)
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-- cases that used to error out
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select 0.12 ^ (-25);
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?column?
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@ -909,6 +909,7 @@ select 3.789 ^ 21;
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select 3.789 ^ 35;
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select 1.2 ^ 345;
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select 0.12 ^ (-20);
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select 1.000000000123 ^ (-2147483648);
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-- cases that used to error out
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select 0.12 ^ (-25);
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