[clang] [include-cleaner] Support multi-header symbols in mapping generator (PR #147720)

[kadir çetinkaya via cfe-commits]

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@@ -497,354 +78,3 @@ SYMBOL(_26, std::placeholders::, <functional>)
 SYMBOL(_27, std::placeholders::, <functional>)
 SYMBOL(_28, std::placeholders::, <functional>)
 SYMBOL(_29, std::placeholders::, <functional>)
-
-// Macros
-SYMBOL(NULL, None, <cstddef>)
-SYMBOL(NULL, None, <stddef.h>)
-SYMBOL(NULL, None, <cstdlib>)
-SYMBOL(NULL, None, <stdlib.h>)
-SYMBOL(NULL, None, <cstring>)
-SYMBOL(NULL, None, <string.h>)
-SYMBOL(NULL, None, <cwchar>)
-SYMBOL(NULL, None, <wchar.h>)
-SYMBOL(NULL, None, <ctime>)
-SYMBOL(NULL, None, <time.h>)
-SYMBOL(NULL, None, <clocale>)
-SYMBOL(NULL, None, <locale.h>)
-SYMBOL(NULL, None, <cstdio>)
-SYMBOL(NULL, None, <stdio.h>)
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kadircet wrote:

thanks a lot for bringing this up, i totally missed this.

it's not just NULL, but also:
- `begin`, `cbegin`, `cend`, `crbegin`, `crend`, `data`, `empty`, `end`, `rbegin`, `rend`, `size`, `ssize` -> should prefer `iterator`
- `hash` -> should prefer `functional`
- `swap` -> should prefer `utility`
- `tuple_size` -> should prefer `tuple`

hopefully changes in the ordering here will be more obvious for smaller changes. but we should pay some extra attention this time.

@cseriildi I think best course of action is filing bugs (or making these changes ourselves) to cppreference to ensure convergence going forward as @itislu also mentioned. but in the meanwhile we should have a way to unblock ourselves, wdyt about having a list of `(namespace, symbol) -> (preffered_header)` mappings to override ordering for these symbols?

https://github.com/llvm/llvm-project/pull/147720