Combining floatLiteral() Node Matcher with isExpansionInFileMatching() Narrowing Matcher provides unexpected results

Clang Frontend
1

Hi,

Combining floatLiteral() Node Matcher with isExpansionInFileMatching() Narrowing Matcher provides unexpected results.
The following matcher: floatLiteral(isExpansionInFileMatching(“include/math.h”))

does not matches “M_E” which is defined in “math.h”

#include <math.h>

int consts(int n){
double varX = M_E;
return varX;
}

It matches a single unrelated node:
FloatingLiteral 0x562c409bdaa8 </usr/include/math.h:1184:47> ‘float’ 0.000000e+00

Am I doing something wrong?
Thanks

2

M_E is a macro and that macro is expanded in your

  double varX = M_E;

line. The expansion is not in math.h. The expansion is in the main file.

  http://ec2-18-191-7-3.us-east-2.compute.amazonaws.com:10240/z/qRMj-W

By the way, we have a llvm channel on the cpplang slack (https://cpplang.slack.com). That is a more suitable venue for your questions. This is the development mailing list.

Thanks,

Stephen.

3

M_E is a macro and that macro is expanded in your

double varX = M_E;

line. The expansion is not in math.h. The expansion is in the main file.

http://ec2-18-191-7-3.us-east-2.compute.amazonaws.com:10240/z/qRMj-W

Thank you so much for the explanation

By the way, we have a llvm channel on the cpplang slack
(https://cpplang.slack.com). That is a more suitable venue for your
questions. This is the development mailing list.

I am sorry that I posted the questions in the wrong place. I didn’t know that clang has a slack channel.

4

> M_E is a macro and that macro is expanded in your
>
> double varX = M_E;
>
> line. The expansion is not in math.h. The expansion is in the main file.
>
> http://ec2-18-191-7-3.us-east-2.compute.amazonaws.com:10240/z/qRMj-W

Thank you so much for the explanation

You probably want to take a look at clang's PPCallbacks, they would allow you
to be informed when such macro expansion happens.

> By the way, we have a llvm channel on the cpplang slack
> (https://cpplang.slack.com). That is a more suitable venue for your
> questions. This is the development mailing list.

I am sorry that I posted the questions in the wrong place. I didn't know that clang has a slack channel.

This is the right place.
I'm not sure a slack channel is more official place.
There are also IRC channels (e.g. see LLVM Project).

Roman.

5

You probably want to take a look at clang’s PPCallbacks, they would allow you
to be informed when such macro expansion happens.
Great, I will check PPCallbacks.

This is the right place.
I’m not sure a slack channel is more official place.
There are also IRC channels (e.g. see LLVM Project).

Any additional resource is always welcome. Thank you