[clang] [-Wunsafe-buffer-usage] Add FixableGadget for AddAssign in UnspecifiedUntypedContext (PR #71862)

[Artem Dergachev via cfe-commits]

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@@ -0,0 +1,55 @@
+// RUN: %clang_cc1 -std=c++20 -Wunsafe-buffer-usage \
+// RUN:            -fsafe-buffer-usage-suggestions \
+// RUN:            -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s
+void foo(int * , int *);
+
+void add_assign_test(unsigned int n, int *a, int y) {
+  int *p = new int[10];
+  // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:3-[[@LINE-1]]:11}:"std::span<int> p"
+  // CHECK: fix-it:"{{.*}}":{[[@LINE-2]]:12-[[@LINE-2]]:12}:"{"
+  // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:23-[[@LINE-3]]:23}:", 10}"
+  p += 2;
+  // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:3-[[@LINE-1]]:9}:"p = p.subspan(2)"
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haoNoQ wrote:

I suspect it needs to be like `p.subspan(0, 2)`. The first argument is offset, the second argument is count. (I wrote it weirdly on the wideboard many times because I never memorized any of this.)

https://github.com/llvm/llvm-project/pull/71862