C++ notes around tooling

1 # clang-format, force multi-line formatting

Add // comment at the end of line to force clang-format to NOT merge everything into single line. This:

const int status = ...;
if ((status == e1) || (status == e2) || other_error)
{
    HandleMe();
}

becomes:

const int status = ...;
if ((status == e1)    //
    || (status == e2) //
    || other_error)
{
    HandleMe();
}

2 # initial clang-format setup

Add header with above info to .clang-format, submit:

# clang-format version 18.1.8
# clang-format.exe --style=Microsoft --dump-config > .clang-format
---
Language:        Cpp
# BasedOnStyle:  Microsoft
...

3 # disable clang-format for piece of code

// clang-format off
MyHandle(56
    , "args"
    , "data"
    );
// clang-format on

4 # clang-format command line for file formatting

Single file:

clang-format.exe -i --style=file:.clang-format "main.cpp"

Folder:

ls -Path . -Recurse -File -Include *.h,*.cpp `
    | % { clang-format.exe -i --style=file:.clang-format $_.FullName }

5 # MSVC: dump class/object memory layout

See /d1reportAllClassLayout – Dumping Object Memory Layout and VC++ 2013 class Layout Change and Wasted Space. For this code:

// main.cpp
struct MyBase
{
    virtual ~MyBase() = default;
    virtual void MyFoo() {};
    int _data = -1;
};

struct MyDerived : MyBase
{
    virtual void MyFoo() override {};
    float _id = 0.0f;
};

Running

cl /d1reportSingleClassLayoutMyDerived main.cpp

will dump:

class MyDerived size(12):
        +---
 0      | +--- (base class MyBase)
 0      | | {vfptr}
 4      | | _data
        | +---
 8      | _id
        +---

MyDerived::$vftable@:
        | &MyDerived_meta
        |  0
 0      | &MyDerived::{dtor}
 1      | &MyDerived::MyFoo

Note there is also /d1reportAllClassLayout so you don’t need to specify class name.