[gcc r15-8384] gccrs: Add extra assertions to tl::optional

[Arthur Cohen via Gcc-cvs]

https://gcc.gnu.org/g:70228a4ba99cdb5a152dceb10aa754bc0acb4aea

commit r15-8384-g70228a4ba99cdb5a152dceb10aa754bc0acb4aea
Author: Owen Avery <powerboat9.ga...@gmail.com>
Date:   Wed Sep 18 16:05:31 2024 -0400

    gccrs: Add extra assertions to tl::optional
    
    gcc/rust/ChangeLog:
    
            * util/optional.h
            (optional): Add assertions to dereference operator overloads
            when C++14 is available.
    
    Signed-off-by: Owen Avery <powerboat9.ga...@gmail.com>

Diff:
---
 gcc/rust/util/optional.h | 86 ++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 79 insertions(+), 7 deletions(-)

diff --git a/gcc/rust/util/optional.h b/gcc/rust/util/optional.h
index b2011b784b76..2c59459cb940 100644
--- a/gcc/rust/util/optional.h
+++ b/gcc/rust/util/optional.h
@@ -1249,19 +1249,56 @@ public:
 
   /// Returns a pointer to the stored value
   constexpr const T *operator->() const {
+    // constexpr function must only contain a return statement in C++11
+#ifdef TL_OPTIONAL_CXX14
+    // undefined behavior if we don't have a value
+    rust_assert(has_value ());
+#endif
+
     return std::addressof(this->m_value);
   }
 
   TL_OPTIONAL_11_CONSTEXPR T *operator->() {
+    // constexpr function must only contain a return statement in C++11
+#ifdef TL_OPTIONAL_CXX14
+    // undefined behavior if we don't have a value
+    rust_assert(has_value ());
+#endif
+
     return std::addressof(this->m_value);
   }
 
   /// Returns the stored value
-  TL_OPTIONAL_11_CONSTEXPR T &operator*() & { return this->m_value; }
+  TL_OPTIONAL_11_CONSTEXPR T &operator*() &
+  {
+    // constexpr function must only contain a return statement in C++11
+#ifdef TL_OPTIONAL_CXX14
+    // undefined behavior if we don't have a value
+    rust_assert(has_value ());
+#endif
 
-  constexpr const T &operator*() const & { return this->m_value; }
+    return this->m_value;
+  }
+
+  constexpr const T &operator*() const &
+  {
+    // constexpr function must only contain a return statement in C++11
+#ifdef TL_OPTIONAL_CXX14
+    // undefined behavior if we don't have a value
+    rust_assert(has_value ());
+#endif
+
+    return this->m_value;
+  }
+
+  TL_OPTIONAL_11_CONSTEXPR T &&operator*() &&
+  {
+    // constexpr function must only contain a return statement in C++11
+#ifdef TL_OPTIONAL_CXX14
+    // undefined behavior if we don't have a value
+    rust_assert(has_value ());
+#endif
 
-  TL_OPTIONAL_11_CONSTEXPR T &&operator*() && {
     return std::move(this->m_value);
   }
 
@@ -1988,14 +2025,49 @@ public:
   void swap(optional &rhs) noexcept { std::swap(m_value, rhs.m_value); }
 
   /// Returns a pointer to the stored value
-  constexpr const T *operator->() const noexcept { return m_value; }
+  constexpr const T *operator->() const noexcept
+  {
+    // constexpr function must only contain a return statement in C++11
+#ifdef TL_OPTIONAL_CXX14
+    // undefined behavior if we don't have a value
+    rust_assert(has_value ());
+#endif
+
+    return m_value;
+  }
 
-  TL_OPTIONAL_11_CONSTEXPR T *operator->() noexcept { return m_value; }
+  TL_OPTIONAL_11_CONSTEXPR T *operator->() noexcept
+  {
+    // constexpr function must only contain a return statement in C++11
+#ifdef TL_OPTIONAL_CXX14
+    // undefined behavior if we don't have a value
+    rust_assert(has_value ());
+#endif
+
+    return m_value;
+  }
 
   /// Returns the stored value
-  TL_OPTIONAL_11_CONSTEXPR T &operator*() noexcept { return *m_value; }
+  TL_OPTIONAL_11_CONSTEXPR T &operator*() noexcept {
+    // constexpr function must only contain a return statement in C++11
+#ifdef TL_OPTIONAL_CXX14
+    // undefined behavior if we don't have a value
+    rust_assert(has_value ());
+#endif
+
+    return *m_value;
+  }
 
-  constexpr const T &operator*() const noexcept { return *m_value; }
+  constexpr const T &operator*() const noexcept
+  {
+    // constexpr function must only contain a return statement in C++11
+#ifdef TL_OPTIONAL_CXX14
+    // undefined behavior if we don't have a value
+    rust_assert(has_value ());
+#endif
+
+    return *m_value;
+  }
 
   constexpr bool has_value() const noexcept { return m_value != nullptr; }