[clang] [clang] Fix the post-filtering heuristic for GSLPointer. (PR #114044)

[Haojian Wu via cfe-commits]

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@@ -793,3 +794,44 @@ void test13() {
 }
 
 } // namespace GH100526
+
+namespace LifetimeboundInterleave {
+
+const std::string& Ref(const std::string& abc [[clang::lifetimebound]]);
+std::string_view test1() {
+  std::string_view t1 = Ref(std::string()); // expected-warning {{object backing}}
+  t1 = Ref(std::string()); // expected-warning {{object backing}}
+  return Ref(std::string()); // expected-warning {{returning address}}
+}
+
+template <typename T>
+struct Foo {
+  const T& get() const [[clang::lifetimebound]];
+  const T& getNoLB() const;
+};
+std::string_view test2(Foo<std::string> r1, Foo<std::string_view> r2) {
+  std::string_view t1 = Foo<std::string>().get(); // expected-warning {{object backing}}
+  t1 = Foo<std::string>().get(); // expected-warning {{object backing}}
+  return r1.get(); // expected-warning {{address of stack}}
+  
+  std::string_view t2 = Foo<std::string_view>().get();
+  t2 = Foo<std::string_view>().get();
+  return r2.get();
+
+  // no warning on no-LB-annotated method.
+  std::string_view t3 = Foo<std::string>().getNoLB(); 
+  t3 = Foo<std::string>().getNoLB(); 
+  return r1.getNoLB(); 
+}
+
+struct Bar {};
+struct [[gsl::Pointer]] Pointer {
+  Pointer(const Bar & bar [[clang::lifetimebound]]);
+};
+Pointer test3(Bar bar) {
+  Pointer p = Pointer(Bar()); // expected-warning {{temporary}}
+  p = Pointer(Bar()); // expected-warning {{object backing}}
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hokein wrote:

This was a false negative before, this patch also fixes it.

https://github.com/llvm/llvm-project/pull/114044