[clang] [-Wunsafe-buffer-usage] Introduce std::array fixits (PR #80084)

[Artem Dergachev via cfe-commits]

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@@ -2495,10 +2470,113 @@ static FixItList fixVariableWithSpan(const VarDecl *VD,
   return fixLocalVarDeclWithSpan(VD, Ctx, getUserFillPlaceHolder(), Handler);
 }
 
+static FixItList fixVarDeclWithArray(const VarDecl *D, const ASTContext &Ctx,
+                                     UnsafeBufferUsageHandler &Handler) {
+  FixItList FixIts{};
+
+  if (auto CAT = dyn_cast<clang::ConstantArrayType>(D->getType())) {
+    const QualType &ArrayEltT = CAT->getElementType();
+    assert(!ArrayEltT.isNull() && "Trying to fix a non-array type variable!");
+
+    // For most types the transformation is simple:
+    //   T foo[10]; => std::array<T, 10> foo;
+    // Cv-specifiers are straigtforward:
+    //   const T foo[10]; => std::array<const T, 10> foo;
+    // Pointers are straightforward:
+    //   T * foo[10]; => std::array<T *, 10> foo;
+    //
+    // However, for const pointers the transformation is different:
+    //   T * const foo[10]; => const std::array<T *, 10> foo;
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haoNoQ wrote:

Hmm, wouldn't `std::array<T *const, 10>` have the exact same behavior in practice? (Though I completely agree that `const std::array<T *, 10>` is more readable.) (Testbed: https://godbolt.org/z/aeohe6jW9)

https://github.com/llvm/llvm-project/pull/80084