[clang] [-Wunsafe-buffer-usage] Warning Libc functions (PR #101583)

[Artem Dergachev via cfe-commits]

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@@ -12383,6 +12383,13 @@ def warn_unsafe_buffer_operation : Warning<
   "%select{unsafe pointer operation|unsafe pointer arithmetic|"
   "unsafe buffer access|function introduces unsafe buffer manipulation|unsafe invocation of span::data}0">,
   InGroup<UnsafeBufferUsage>, DefaultIgnore;
+def warn_unsafe_buffer_libc_call : Warning<
+  "function %0 introduces unsafe buffer access">,
+  InGroup<UnsafeBufferUsage>, DefaultIgnore;
+def note_unsafe_buffer_printf_call : Note<
+  "%select{| change to 'snprintf' for explicit bounds checking | buffer pointer and size may not match"
+          "| use 'std::string::c_str' or string literal as string pointer to guarantee null-termination"
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haoNoQ wrote:

Also if `-Wunsafe-buffer-usage` is enabled in C (for any obscure reason), would we still recommend `c_str` here? Maybe this recommendation should be guarded by the "emit suggestions" flag?

https://github.com/llvm/llvm-project/pull/101583