fix(build): replace {0} zero-init with {}

[gnosek]

Apparently my compiler (gcc (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0) does not like initializing structs with {0} at all.

Honestly, I'm not convinced this is valid C++ either, though I'm pretty sure it is valid C. E.g. this page:
https://en.cppreference.com/w/cpp/language/zero_initialization does not mention {0} as a valid way to zero-initialize a struct.

What type of PR is this?

Uncomment one (or more) /kind <> lines:

/kind bug

/kind cleanup

/kind design

/kind documentation

/kind failing-test

/kind feature

Any specific area of the project related to this PR?

Uncomment one (or more) /area <> lines:

/area API-version

/area build

/area CI

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/area driver-modern-bpf

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Does this PR require a change in the driver versions?

/version driver-API-version-major

/version driver-API-version-minor

/version driver-API-version-patch

/version driver-SCHEMA-version-major

/version driver-SCHEMA-version-minor

/version driver-SCHEMA-version-patch

What this PR does / why we need it:

Not sure how it works for everybody else, but I'm getting tons of build errors for struct initialization that does seem off.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

[gnosek]

@federico-sysdig please take a look

[Andreagit97]

/approve

[poiana]

LGTM label has been added.

Git tree hash: c452a825fecf240f8bed3bc648a14c9a35ecd873

[FedeDP]

/approve

[federico-sysdig]

LGTM. Great change!
To my surprise, the empty braces syntax does indeed initialize all struct members without a default constructor (such as built-in integers) to zero. Note that this should only apply to C++, not C.
https://en.cppreference.com/w/cpp/language/zero_initialization
I just had to "paranoidly" see it live for myself. For the curious ones, here's the code:

#include <iostream>
#include <cstring>

struct widget
{
  int val1;
  int val2;
  short val3;
  int val4;
};

int main()
{
  char buffer1[sizeof(widget)];
  char buffer2[sizeof(widget)];
  memset(buffer1, 1, sizeof(buffer1));
  memset(buffer2, 1, sizeof(buffer2));

  widget* ptr1 = new (buffer1)widget;
  widget* ptr2 = new (buffer2)widget{}; // the magic is here

  std::cout << ptr1->val1 << " - "
            << ptr1->val2 << " - "
            << ptr1->val3 << " - "
            << ptr1->val4 << '\n';

  std::cout << ptr2->val1 << " - "
            << ptr2->val2 << " - "
            << ptr2->val3 << " - "
            << ptr2->val4 << '\n';
}

Possible output:

16843009 - 16843009 - 257 - 16843009
0 - 0 - 0 - 0

NOTE: I have no idea how your compilation error was never detected. It's another surprise that this code never went through a gcc version similar to yours.

[poiana]

@federico-sysdig: changing LGTM is restricted to collaborators

In response to this:

LGTM. Great change!
To my surprise, the empty braces syntax does indeed initialize all struct members without a default constructor (such as built-in integers) to zero.
https://en.cppreference.com/w/cpp/language/zero_initialization
I just had to "paranoidly" see it live for myself. For the curious ones, here's the code:

#include <iostream>
#include <cstring>

struct widget
{
 int val1;
 int val2;
 short val3;
 int val4;
};

int main()
{
 char buffer1[sizeof(widget)];
 char buffer2[sizeof(widget)];
 memset(buffer1, 1, sizeof(buffer1));
 memset(buffer2, 1, sizeof(buffer2));

 widget* ptr1 = new (buffer1)widget;
 widget* ptr2 = new (buffer2)widget{};

 std::cout << ptr1->val1 << " - "
           << ptr1->val2 << " - "
           << ptr1->val3 << " - "
           << ptr1->val4 << '\n';

 std::cout << ptr2->val1 << " - "
           << ptr2->val2 << " - "
           << ptr2->val3 << " - "
           << ptr2->val4 << '\n';
}

Possible output:

16843009 - 16843009 - 257 - 16843009
0 - 0 - 0 - 0

NOTE: I have no idea how your compilation error was never detected. It's another surprise that this code never went through a gcc version similar to yours.

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[poiana]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Andreagit97, FedeDP, federico-sysdig, gnosek

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