assigning float into int variable causes no warning

Question

So, given the following code:

int main(void) {
  int i;
  i = 12.1234;
  i++;
  return 0;
}

I compiled the code and I expected and wanted t

Answer 1

You may expect that -Wall does enable ALL warnings, but it doesn't! There are a lot of warnings that doesn't even make sense in the wrong environment.

It is an aggregation of the following flags:

  -Waddress   
  -Warray-bounds (only with -O2)  
  -Wc++11-compat  
  -Wchar-subscripts  
  -Wenum-compare (in C/ObjC; this is on by default in C++) 
  -Wimplicit-int (C and Objective-C only) 
  -Wimplicit-function-declaration (C and Objective-C only) 
  -Wcomment  
  -Wformat   
  -Wmain (only for C/ObjC and unless -ffreestanding)  
  -Wmaybe-uninitialized 
  -Wmissing-braces (only for C/ObjC) 
  -Wnonnull  
  -Wparentheses  
  -Wpointer-sign  
  -Wreorder   
  -Wreturn-type  
  -Wsequence-point  
  -Wsign-compare (only in C++)  
  -Wstrict-aliasing  
  -Wstrict-overflow=1  
  -Wswitch  
  -Wtrigraphs  
  -Wuninitialized  
  -Wunknown-pragmas  
  -Wunused-function  
  -Wunused-label     
  -Wunused-value     
  -Wunused-variable  
  -Wvolatile-register-var

as described here: https://gcc.gnu.org/onlinedocs/gcc-4.8.2/gcc/Warning-Options.html

What you need is -Wconversion as mentioned above. Another quite useful flag may be -Wextra.