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Commit0e3e8fb

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Fix corner-case 64-bit integer subtraction bug on some platforms.
When computing "0 - INT64_MIN", most platforms would report anoverflow error, which is correct. However, platforms without integeroverflow builtins or 128-bit integers would fail to spot the overflow,and incorrectly return INT64_MIN.Back-patch to all supported branches.Patch be me. Thanks to Jian He for initial investigation, and LaurenzAlbe and Tom Lane for review.Discussion:https://postgr.es/m/CAEZATCUNK-AZSD0jVdgkk0N%3DNcAXBWeAEX-QU9AnJPensikmdQ%40mail.gmail.com
1 parenta7db71e commit0e3e8fb

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3 files changed

+8
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‎src/include/common/int.h

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@@ -200,8 +200,12 @@ pg_sub_s64_overflow(int64 a, int64 b, int64 *result)
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*result= (int64)res;
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return false;
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#else
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/*
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* Note: overflow is also possible when a == 0 and b < 0 (specifically,
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* when b == PG_INT64_MIN).
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*/
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if ((a<0&&b>0&&a<PG_INT64_MIN+b)||
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(a>0&&b<0&&a>PG_INT64_MAX+b))
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(a >=0&&b<0&&a>PG_INT64_MAX+b))
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{
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*result=0x5EED;/* to avoid spurious warnings */
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return true;

‎src/test/regress/expected/int8.out

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@@ -679,6 +679,8 @@ select -('-9223372036854775807'::int8);
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select -('-9223372036854775808'::int8);
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ERROR: bigint out of range
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select 0::int8 - '-9223372036854775808'::int8;
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ERROR: bigint out of range
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select '9223372036854775800'::int8 + '9223372036854775800'::int8;
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ERROR: bigint out of range
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select '-9223372036854775800'::int8 + '-9223372036854775800'::int8;

‎src/test/regress/sql/int8.sql

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Original file line numberDiff line numberDiff line change
@@ -132,6 +132,7 @@ select '9223372036854775808'::int8;
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select-('-9223372036854775807'::int8);
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select-('-9223372036854775808'::int8);
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select0::int8-'-9223372036854775808'::int8;
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select'9223372036854775800'::int8+'9223372036854775800'::int8;
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select'-9223372036854775800'::int8+'-9223372036854775800'::int8;

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