[clang] [Clang] Instantiate constexpr function when they are needed. (PR #173537)

[Timm Baeder via cfe-commits]

================
@@ -1526,13 +1527,30 @@ bool CheckFunctionDecl(InterpState &S, CodePtr OpPC, const FunctionDecl *FD) {
   return diagnoseCallableDecl(S, OpPC, FD);
 }
 
-static void compileFunction(InterpState &S, const Function *Func) {
-  const FunctionDecl *Definition = Func->getDecl()->getDefinition();
-  if (!Definition)
+static void compileFunction(InterpState &S, const Function *Func,
+                            SourceLocation Loc) {
----------------
tbaederr wrote:

Pass a `CodePtr` instead of `Loc` and do the `getLocation()` call when needed.

https://github.com/llvm/llvm-project/pull/173537