Reported coordinates not accurate for BinaryOp while getting json dump of AST

[akash-isu]

Look at this code:

#include<stdio.h>
int main(int argc, char \*argv[]) { 
	int a,i,j,k;
	scanf("%d",&a);
	k=a%10;
	j=a/10%10;
	if(a>0)
		printf("%d",a);
	else 
	{
		if(k>j)
			printf("%d",a/100\*10+k);
		
		else printf("%d",a/10);

	}
	return 0;
}

And consider the only the JSON output for only the binary operators:

{'_nodetype': 'BinaryOp', 'coord': '313-A-bug-16465019-16465065/313-A-16465065.c:6:4', 'left': {'_nodetype': 'BinaryOp', 'coord': '313-A-bug-16465019-16465065/313-A-16465065.c:6:4', 'left': {'_nodetype': 'ID', 'coord': '313-A-bug-16465019-16465065/313-A-16465065.c:6:4', 'name': 'a'}, 'op': '/', 'right': {'_nodetype': 'Constant', 'coord': '313-A-bug-16465019-16465065/313-A-16465065.c:6:6', 'type': 'int', 'value': '10'}}, 'op': '%', 'right': {'_nodetype': 'Constant', 'coord': '313-A-bug-16465019-16465065/313-A-16465065.c:6:9', 'type': 'int', 'value': '10'}}

{'_nodetype': 'BinaryOp', 'coord': '313-A-bug-16465019-16465065/313-A-16465065.c:6:4', 'left': {'_nodetype': 'ID', 'coord': '313-A-bug-16465019-16465065/313-A-16465065.c:6:4', 'name': 'a'}, 'op': '/', 'right': {'_nodetype': 'Constant', 'coord': '313-A-bug-16465019-16465065/313-A-16465065.c:6:6', 'type': 'int', 'value': '10'}}

How can the coordinates 6:4 have 2 operators? (namely '%' and '/')
This is the line in question:
j=a/10%10;

Am I missing something or is this the expected behavior?
I've only included the sections of the JSON in question for easier readability.

[eliben]

A simpler reproducer:

int a = b / 10 % 20;

It seems like the coordinate attribution for binary ops could be improved, though it's not clear what the right way to report it is. The way it currently works is that the BinaryOp node gets the coord of its LHS. In this case both LHSes start at the first a. Alternatively the op's coord could be its operator's coord, though it's not clear whether this is the best choice either.

[akash-isu]

To me, a good approach seems to be a relative coordinate reporting for the individual operators wrt the index of the LHS.
For example, for the given instance:
if the coord of the LHS is 1:4, then the coord for '/' can be 1:4:6, where 6 is the number of spaces between the LHS and the operator.
I suggest this approach, as the 'tab' and 'space' counts often varies between the actual code and the pre-processed code.

[eliben]

I think that what's often done is nodes would have a start coord and end coord, covering their extent, e.g. consider:

int a 
     +
     b;

This is valid code, and yet where would you report the coord for the binary op node? Right now it's reported on a, but it could also legitimately be on +. It could be that we want to extend it to be with a start coord + end coord, covering the whole binary op.

It's a large feature request though.

[JulianKemmerer]

This is probably bad advice - but what I did to get around this issue in the meantime when I came across it
(which at the time, I thought too roughly it's not clear what the right way to report it is and that it would always be an issue...)
was to identify with the normal ex. 1:4 but then also did a python like hash(str(c_ast_node)) The two nodes have the same coord but their text representation is still unique - hash converts it to some number. Saving identifiers like my_bin_op_1:4_0xdeadbeef