[libc-commits] [libc] [libc] Move from alias(X) to asm(X) for aliasing (PR #89333)

[Nick Desaulniers via libc-commits]

nickdesaulniers wrote:

Yeah that seems to work on the small scale to fix #60481.

```
$ cd <new build dir>
$ cmake ../llvm -DLLVM_ENABLE_PROJECTS="libc" -DCMAKE_BUILD_TYPE=Release -G Ninja
$ ninja libc.src.stdlib.bsearch
<explosion from #60481>
```
apply the above diff plus:
```diff

















diff --git a/libc/src/stdlib/bsearch.cpp b/libc/src/stdlib/bsearch.cpp
index 4292d6b6fe04..fe02f5fb8366 100644
--- a/libc/src/stdlib/bsearch.cpp
+++ b/libc/src/stdlib/bsearch.cpp
@@ -9,9 +9,8 @@
 #include "src/stdlib/bsearch.h"
 #include "src/__support/common.h"
 
-#include <stdint.h>
-
-namespace LIBC_NAMESPACE {
+#include <stdint.h> // uint8_t
+#include <stddef.h> // size_t
 
 LLVM_LIBC_FUNCTION(void *, bsearch,
                    (const void *key, const void *array, size_t array_size,
@@ -43,5 +42,3 @@ LLVM_LIBC_FUNCTION(void *, bsearch,
 
   return nullptr;
 }
-
-} // namespace LIBC_NAMESPACE
diff --git a/libc/src/stdlib/bsearch.h b/libc/src/stdlib/bsearch.h
index 1de7e051ff6c..cf3188c3adc7 100644
--- a/libc/src/stdlib/bsearch.h
+++ b/libc/src/stdlib/bsearch.h
@@ -9,13 +9,9 @@
 #ifndef LLVM_LIBC_SRC_STDLIB_BSEARCH_H
 #define LLVM_LIBC_SRC_STDLIB_BSEARCH_H
 
-#include <stdlib.h>
+#include <stddef.h> // size_t
 
-namespace LIBC_NAMESPACE {
-
-void *bsearch(const void *key, const void *array, size_t array_size,
+extern "C" void *bsearch(const void *key, const void *array, size_t array_size,
               size_t elem_size, int (*compare)(const void *, const void *));
 
-} // namespace LIBC_NAMESPACE
-
 #endif //LLVM_LIBC_SRC_STDLIB_BSEARCH_H
 ```
```
$ ninja libc.src.stdlib.bsearch
$ llvm-readelf -sW projects/libc/src/stdlib/CMakeFiles/libc.src.stdlib.bsearch.dir/bsearch.cpp.o | llvm-cxxfilt

Symbol table '.symtab' contains 4 entries:
   Num:    Value          Size Type    Bind   Vis       Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT   UND 
     1: 0000000000000000     0 FILE    LOCAL  DEFAULT   ABS bsearch.cpp
     2: 0000000000000000   154 FUNC    GLOBAL DEFAULT     4 bsearch
     3: 0000000000000000   154 FUNC    GLOBAL DEFAULT     4 __llvm_libc_19_0_0_git::bsearch(void const*, void const*, unsigned long, unsigned long, int (*)(void const*, void const*))
```

https://github.com/llvm/llvm-project/pull/89333