[clang] [clang] Document -Wglobal-constructors behavior (PR #68084)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

<details>
<summary>Changes</summary>

It's a drop in the ocean considering the lack of documentation of our diagnostics, but it's a start.

---
Full diff: https://github.com/llvm/llvm-project/pull/68084.diff


1 Files Affected:

- (modified) clang/include/clang/Basic/DiagnosticGroups.td (+5-1) 


``````````diff
diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td
index 0b09c002191848a..55e15e68764c42b 100644
--- a/clang/include/clang/Basic/DiagnosticGroups.td
+++ b/clang/include/clang/Basic/DiagnosticGroups.td
@@ -416,7 +416,11 @@ def : DiagGroup<"c++2a-compat-pedantic", [CXX20CompatPedantic]>;
 def ExitTimeDestructors : DiagGroup<"exit-time-destructors">;
 def FlexibleArrayExtensions : DiagGroup<"flexible-array-extensions">;
 def FourByteMultiChar : DiagGroup<"four-char-constants">;
-def GlobalConstructors : DiagGroup<"global-constructors">;
+def GlobalConstructors : DiagGroup<"global-constructors"> {
+ code Documentation = [{
+Emit a warning for each variable declaration that generates code run at startup.
+ }];
+}
 def BitwiseConditionalParentheses: DiagGroup<"bitwise-conditional-parentheses">;
 def BitwiseOpParentheses: DiagGroup<"bitwise-op-parentheses">;
 def LogicalOpParentheses: DiagGroup<"logical-op-parentheses">;

``````````

</details>


https://github.com/llvm/llvm-project/pull/68084