Constant expressions should not be reduced

[dopelsunce]

Hi, here is the issue we talked about briefly in the meeting.

foo.c

char a[10 - 1];
char b[128 - sizeof(long)];

cconv-standalone -alltypes foo.c

Returns:

char a _Checked[9];
char b _Checked[120];

Wanted:

char a _Checked[10 - 1];
char b _Checked[128 - sizeof(long)];

It might be best to keep the constant expression as is.

[john-h-kastner]

We definitely don't want to be rewriting those.

It looks like clang is folding constants before we even get our hands on the AST, so all we see is

|-VarDecl 0x55da5b541ee8 <h.c:1:1, col:14> col:6 a 'char [9]'
`-VarDecl 0x55da5b5420b8 <line:2:1, col:26> col:6 b 'char [120]'

This means the fix will be some finicky rewriting logic. Instead of clobbering the declaration, we'll need to carefully insert Checked where it's needed.

Here's a more general example that shows what's happening.

char c[1 /*a very important comment*/];

is rewritten to

char c _Checked[1];

[mwhicks1]

Wow this a big one. Seems like this is pushing for a larger re-do of rewriting ...