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warn if ++ or -- are unable to change the value because it's beyond
[perl5.git] / t / op / inc.t
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3510b4a1 1#!./perl -w
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3# use strict;
4
b88df990 5print "1..50\n";
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6
7my $test = 1;
8
9sub ok {
10 my ($pass, $wrong, $err) = @_;
11 if ($pass) {
12 print "ok $test\n";
13 $test = $test + 1; # Would be doubleplusbad to use ++ in the ++ test.
14 return 1;
15 } else {
16 if ($err) {
17 chomp $err;
18 print "not ok $test # $err\n";
19 } else {
20 if (defined $wrong) {
21 $wrong = ", got $wrong";
22 } else {
23 $wrong = '';
24 }
25 printf "not ok $test # line %d$wrong\n", (caller)[2];
26 }
27 }
28 $test = $test + 1;
29 return;
30}
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31
32# Verify that addition/subtraction properly upgrade to doubles.
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33# These tests are only significant on machines with 32 bit longs,
34# and two's complement negation, but shouldn't fail anywhere.
760ac839 35
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36my $a = 2147483647;
37my $c=$a++;
38ok ($a == 2147483648, $a);
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39
40$a = 2147483647;
41$c=++$a;
3510b4a1 42ok ($a == 2147483648, $a);
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43
44$a = 2147483647;
45$a=$a+1;
3510b4a1 46ok ($a == 2147483648, $a);
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47
48$a = -2147483648;
49$c=$a--;
3510b4a1 50ok ($a == -2147483649, $a);
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51
52$a = -2147483648;
53$c=--$a;
3510b4a1 54ok ($a == -2147483649, $a);
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55
56$a = -2147483648;
57$a=$a-1;
3510b4a1 58ok ($a == -2147483649, $a);
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59
60$a = 2147483648;
61$a = -$a;
62$c=$a--;
3510b4a1 63ok ($a == -2147483649, $a);
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64
65$a = 2147483648;
66$a = -$a;
67$c=--$a;
3510b4a1 68ok ($a == -2147483649, $a);
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69
70$a = 2147483648;
71$a = -$a;
72$a=$a-1;
3510b4a1 73ok ($a == -2147483649, $a);
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74
75$a = 2147483648;
76$b = -$a;
77$c=$b--;
3510b4a1 78ok ($b == -$a-1, $a);
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79
80$a = 2147483648;
81$b = -$a;
82$c=--$b;
3510b4a1 83ok ($b == -$a-1, $a);
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84
85$a = 2147483648;
86$b = -$a;
87$b=$b-1;
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88ok ($b == -(++$a), $a);
89
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HS
90$a = undef;
91ok ($a++ eq '0', do { $a=undef; $a++ }, "postinc undef returns '0'");
92
93$a = undef;
94ok (!defined($a--), do { $a=undef; $a-- }, "postdec undef returns undef");
95
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96# Verify that shared hash keys become unshared.
97
98sub check_same {
99 my ($orig, $suspect) = @_;
100 my $fail;
101 while (my ($key, $value) = each %$suspect) {
102 if (exists $orig->{$key}) {
103 if ($orig->{$key} ne $value) {
104 print "# key '$key' was '$orig->{$key}' now '$value'\n";
105 $fail = 1;
106 }
107 } else {
108 print "# key '$key' is '$orig->{$key}', unexpect.\n";
109 $fail = 1;
110 }
111 }
112 foreach (keys %$orig) {
113 next if (exists $suspect->{$_});
114 print "# key '$_' was '$orig->{$_}' now missing\n";
115 $fail = 1;
116 }
117 ok (!$fail);
118}
119
120my (%orig) = my (%inc) = my (%dec) = my (%postinc) = my (%postdec)
121 = (1 => 1, ab => "ab");
122my %up = (1=>2, ab => 'ac');
123my %down = (1=>0, ab => -1);
124
125foreach (keys %inc) {
126 my $ans = $up{$_};
127 my $up;
128 eval {$up = ++$_};
129 ok ((defined $up and $up eq $ans), $up, $@);
130}
131
132check_same (\%orig, \%inc);
133
134foreach (keys %dec) {
135 my $ans = $down{$_};
136 my $down;
137 eval {$down = --$_};
138 ok ((defined $down and $down eq $ans), $down, $@);
139}
140
141check_same (\%orig, \%dec);
142
143foreach (keys %postinc) {
144 my $ans = $postinc{$_};
145 my $up;
146 eval {$up = $_++};
147 ok ((defined $up and $up eq $ans), $up, $@);
148}
149
150check_same (\%orig, \%postinc);
151
152foreach (keys %postdec) {
153 my $ans = $postdec{$_};
154 my $down;
155 eval {$down = $_--};
156 ok ((defined $down and $down eq $ans), $down, $@);
157}
158
159check_same (\%orig, \%postdec);
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160
161{
162 no warnings 'uninitialized';
840378f5 163 my ($x, $y);
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164 eval {
165 $y ="$x\n";
166 ++$x;
167 };
168 ok($x == 1, $x);
169 ok($@ eq '', $@);
170
840378f5 171 my ($p, $q);
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172 eval {
173 $q ="$p\n";
174 --$p;
175 };
176 ok($p == -1, $p);
177 ok($@ eq '', $@);
178}
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179
180$a = 2147483648;
181$c=--$a;
182ok ($a == 2147483647, $a);
183
184
185$a = 2147483648;
186$c=$a--;
187ok ($a == 2147483647, $a);
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188
189{
190 use integer;
191 my $x = 0;
192 $x++;
193 ok ($x == 1, "(void) i_postinc");
194 $x--;
195 ok ($x == 0, "(void) i_postdec");
196}
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197
198# I'm sure that there's an IBM format with a 48 bit mantissa
199# IEEE doubles have a 53 bit mantissa
200# 80 bit long doubles have a 64 bit mantissa
201# sparcs have a 112 bit mantissa for their long doubles. Just to be awkward :-)
202
203sub check_some_code {
204 my ($start, $warn, $action, $description) = @_;
205 my $warn_line = ($warn ? 'use' : 'no') . " warnings 'imprecision';";
206 my @warnings;
207 local $SIG{__WARN__} = sub {push @warnings, "@_"};
208
209 print "# checking $action under $warn_line\n";
210 my $code = <<"EOC";
211$warn_line
212my \$i = \$start;
213for(0 .. 3) {
214 my \$a = $action;
215}
2161;
217EOC
218 eval $code or die "# $@\n$code";
219
220 if ($warn) {
221 unless (ok (scalar @warnings == 2, scalar @warnings)) {
222 print STDERR "# $_" foreach @warnings;
223 }
224 foreach (@warnings) {
225 unless (ok (/Lost precision when incrementing \d+/, $_)) {
226 print STDERR "# $_"
227 }
228 }
229 } else {
230 unless (ok (scalar @warnings == 0)) {
231 print STDERR "# @$_" foreach @warnings;
232 }
233 }
234}
235
236my $found;
237for my $n (47..113) {
238 my $power_of_2 = 2**$n;
239 my $plus_1 = $power_of_2 + 1;
240 next if $plus_1 != $power_of_2;
241 print "# Testing for 2**$n ($power_of_2) which overflows the mantissa\n";
242 # doing int here means that for NV > IV on the first go we're in the
243 # IV upgrade to NV case, and the second go we're in the NV already case.
244 my $start = int($power_of_2 - 2);
245 my $check = $power_of_2 - 2;
246 die "Something wrong with our rounding assumptions: $check vs $start"
247 unless $start == $check;
248
249 foreach my $warn (0, 1) {
250 foreach (['++$i', 'pre-inc'], ['$i++', 'post-inc']) {
251 check_some_code($start, $warn, @$_);
252 }
253 foreach (['--$i', 'pre-dec'], ['$i--', 'post-dec']) {
254 check_some_code(-$start, $warn, @$_);
255 }
256 }
257
258 $found = 1;
259 last;
260}
261die "Could not find a value which overflows the mantissa" unless $found;