[c++20] P1143R2: Add support for the C++20 'constinit' keyword.

This is mostly the same as the
[[clang::require_constant_initialization]] attribute, but has a couple
of additional syntactic and semantic restrictions.

In passing, I added a warning for the attribute form being added after
we have already seen the initialization of the variable (but before we
see the definition); that case previously slipped between the cracks and
the attribute was silently ignored.

llvm-svn: 370972

1 files changed, 16 insertions, 0 deletions

diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 21dd5425834..6c0c8281460 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -2220,6 +2220,22 @@ Stmt **VarDecl::getInitAddress() {
   return Init.getAddrOfPtr1();
 }
 
+VarDecl *VarDecl::getInitializingDeclaration() {
+  VarDecl *Def = nullptr;
+  for (auto I : redecls()) {
+    if (I->hasInit())
+      return I;
+
+    if (I->isThisDeclarationADefinition()) {
+      if (isStaticDataMember())
+        return I;
+      else
+        Def = I;
+    }
+  }
+  return Def;
+}
+
 bool VarDecl::isOutOfLine() const {
   if (Decl::isOutOfLine())
     return true;