Expr: Warn on count underflow for c -= 1 and c = c - 1

I've skipped treating overflows as warnings, as ++ wrapping around at 0
doesn't currently trigger a runtime error and might be expected to be
quiet and silently wrap.

Closes #2486
This commit is contained in:
Arne Welzel 2022-11-29 15:58:36 +01:00
parent a07b0c333f
commit e48618e244
7 changed files with 67 additions and 2 deletions

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### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
expression warning in <...>/count-underflow.zeek, line 10: count underflow (--c1)
expression warning in <...>/count-underflow.zeek, line 14: count underflow (c2 - 1)
expression warning in <...>/count-underflow.zeek, line 18: count underflow (c3 - 1)
expression warning in <...>/count-underflow.zeek, line 22: count underflow (1 - 2)

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### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
local c1 = 0; --c1; c1 == 18446744073709551615; T
local c2 = 0; c2 -= 1; c2 == 18446744073709551615; T
local c3 = 0; c3 = c3 - 1; c3 == 18446744073709551615; T
1 - 2, 18446744073709551615
local c4 = count_max; ++c4; c4 == 0; T
local c5 = count_max; c5 += 1; c5 == 0; T
local c6 = count_max; c6 = c6 + 1; c6 == 0; T

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### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
expression warning in <...>/sizeof.zeek, line 73: count underflow (5 - 9)

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# @TEST-EXEC: zeek -b %INPUT >out
# @TEST-EXEC: btest-diff out
# @TEST-EXEC: TEST_DIFF_CANONIFIER=$SCRIPTS/diff-remove-abspath btest-diff .stderr
global count_max: count = 0xffffffffffffffff;
event zeek_init()
{
local c1 = 0;
--c1;
print fmt("local c1 = 0; --c1; c1 == %s; %s", c1, c1 == count_max);
local c2 = 0;
c2 -= 1;
print fmt("local c2 = 0; c2 -= 1; c2 == %s; %s", c2, c2 == count_max);
local c3 = 0;
c3 = c3 - 1;
print fmt("local c3 = 0; c3 = c3 - 1; c3 == %s; %s", c3, c3 == count_max);
# This also triggers a warning now;
print "1 - 2", 1 - 2;
# The following ones all overflow back to 0, but do not log a warning.
local c4 = count_max;
++c4;
print fmt("local c4 = count_max; ++c4; c4 == %s; %s", c4, c4 == 0);
local c5 = count_max;
c5 += 1;
print fmt("local c5 = count_max; c5 += 1; c5 == %s; %s", c5, c5 == 0);
local c6 = count_max;
c6 = c6 + 1;
print fmt("local c6 = count_max; c6 = c6 + 1; c6 == %s; %s", c6, c6 == 0);
}

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# @TEST-EXEC: zeek -b %INPUT >output 2>&1
# @TEST-EXEC: zeek -b %INPUT >output
# @TEST-EXEC: btest-diff output
# @TEST-EXEC: TEST_DIFF_CANONIFIER=$SCRIPTS/diff-remove-abspath btest-diff .stderr
# Demo policy for the sizeof operator "|x|".
# ------------------------------------------