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Displaying posts with tag: compiler (reset)

Integer overflow
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What do you think of this piece of C code?

  void foo(long v) {
    unsigned long u;
    unsigned sign;
    if (v < 0) {
      u = -v;
      sign = 1;
    } else {
      u = v;
      sign = 0;
    }
    ...
Seems pretty simple, right? Then what do you think of this output from MySQL:
  mysql> create table t1 (a bigint) as select '-9223372036854775807.5' as a;
  mysql> select * from t1;
  +----------------------+
  | a                    |
  +----------------------+
  | -'..--).0-*(+,))+(0( | 
  +----------------------+
Yes, that is authentic output from older versions of MySQL. Not just the wrong number, the output is complete garbage! This is my all-time favorite MySQL bug#31799. It was caused by code like the above C snippet.

So can you spot what is wrong with the code? Looks pretty simple, does it

  [Read more...]
Warnings are now actual problems
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Yesterday, I reached a happy milestone in HailDB development. All compiler warnings left in the api/ directory (the public interface to the database engine) are now either probable/possible bugs (that we need to look at closely) or are warnings due to unfinished code (that we should finish).

There’s still a bunch of compiler warnings that we’ve inherited (HailDB compiles with lots of warnings enabled) that we have to get through, but a lot will wait until after we update the core to be based on InnoDB 1.1.

Showing entries 1 to 2

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