[clang] [clang] Infer lifetime_capture_by for STL containers (PR #117122)

[Haojian Wu via cfe-commits]

================
@@ -268,6 +268,40 @@ void Sema::inferLifetimeBoundAttribute(FunctionDecl *FD) {
   }
 }
 
+static bool IsPointerLikeType(QualType QT) {
+  QT = QT.getNonReferenceType();
+  if (QT->isPointerType())
+    return true;
+  auto *RD = QT->getAsCXXRecordDecl();
+  if (!RD)
+    return false;
+  RD = RD->getCanonicalDecl();
+  if (auto *CTSD = dyn_cast<ClassTemplateSpecializationDecl>(RD))
+    RD = CTSD->getSpecializedTemplate()->getTemplatedDecl();
----------------
hokein wrote:

hmm, this is strange. I tested it locally, it works for me.

```
$ cat /t/t6.cpp
#include <vector>

template<typename T>
struct [[gsl::Pointer]] Span {
  Span(const std::vector<T> &V);
};

void use() {
  Span<int> pp(std::vector<int>{});
  std::vector<Span<int>> spans;
  spans.push_back(std::vector<int>()); // warning.
}
$ ./bin/clang -Xclang -fsyntax-only -Wdangling-capture /t/t6.cpp                                                                                                                             <<<

/t/t6.cpp:9:16: warning: object backing the pointer will be destroyed at the end of the full-expression [-Wdangling-gsl]
    9 |   Span<int> pp(std::vector<int>{});
      |                ^~~~~~~~~~~~~~~~~~
/t/t6.cpp:11:19: warning: object whose reference is captured by 'spans' will be destroyed at the end of the full-expression [-Wdangling-capture]
   11 |   spans.push_back(std::vector<int>()); // warning.
      |                   ^~~~~~~~~~~~~~~~~~
2 warnings generated.
/usr/bin/ld: /lib/x86_64-linux-gnu/Scrt1.o: in function `_start':
(.text+0x17): undefined reference to `main'
clang: error: linker command failed with exit code 1 (use -v to see invocation)
```

https://github.com/llvm/llvm-project/pull/117122