[clang][ExprConst] Move getLangOpts() to interp::State subclasses (#159280)

Instead of having `State::getLangOpts()`, which does a virtual call to
`getASTContext()` to call `getLangOpts()` on that, just move
`getLangOpts()` to the subclasses so we can do that without the virtual
call. We never call `getLangOpts()` in `State.cpp`, so it's not needed
in the base class.

Author: tbaederr

clang/lib/AST/ByteCode/InterpState.h

@@ -68,6 +68,9 @@ class InterpState final : public State, public SourceMapper {
     return Parent.getEvalStatus();
   }
   ASTContext &getASTContext() const override { return Ctx.getASTContext(); }
+  const LangOptions &getLangOpts() const {
+    return Ctx.getASTContext().getLangOpts();
+  }
 
   // Forward status checks and updates to the walker.
   bool keepEvaluatingAfterFailure() const override {

clang/lib/AST/ByteCode/State.cpp

@@ -112,10 +112,6 @@ OptionalDiagnostic State::diag(SourceLocation Loc, diag::kind DiagId,
   return OptionalDiagnostic();
 }
 
-const LangOptions &State::getLangOpts() const {
-  return getASTContext().getLangOpts();
-}
-
 void State::addCallStack(unsigned Limit) {
   // Determine which calls to skip, if any.
   unsigned ActiveCalls = getCallStackDepth() - 1;

clang/lib/AST/ByteCode/State.h

@@ -151,8 +151,6 @@ class State {
   /// Directly reports a diagnostic message.
   DiagnosticBuilder report(SourceLocation Loc, diag::kind DiagId);
 
-  const LangOptions &getLangOpts() const;
-
   /// Whether or not we're in a context where the front end requires a
   /// constant value.
   bool InConstantContext = false;

clang/lib/AST/ExprConstant.cpp

@@ -945,6 +945,7 @@ namespace {
     }
 
     ASTContext &getASTContext() const override { return Ctx; }
+    const LangOptions &getLangOpts() const { return Ctx.getLangOpts(); }
 
     void setEvaluatingDecl(APValue::LValueBase Base, APValue &Value,
                            EvaluatingDeclKind EDK = EvaluatingDeclKind::Ctor) {