[clang-repl] Always clean up scope and context for TopLevelStmtDecl (llvm#150215)

This fixes an issue introduced by
llvm#84150, where failing to pop
compound scope, function scope info, and decl context after a failed
statement could lead to an inconsistent internal state.

Author: devajithvs

clang/lib/Parse/ParseDecl.cpp

@@ -5695,11 +5695,10 @@ Parser::DeclGroupPtrTy Parser::ParseTopLevelStmtDecl() {
                                Scope::CompoundStmtScope);
   TopLevelStmtDecl *TLSD = Actions.ActOnStartTopLevelStmtDecl(getCurScope());
   StmtResult R = ParseStatementOrDeclaration(Stmts, SubStmtCtx);
+  Actions.ActOnFinishTopLevelStmtDecl(TLSD, R.get());
   if (!R.isUsable())
     R = Actions.ActOnNullStmt(Tok.getLocation());
 
-  Actions.ActOnFinishTopLevelStmtDecl(TLSD, R.get());
-
   if (Tok.is(tok::annot_repl_input_end) &&
       Tok.getAnnotationValue() != nullptr) {
     ConsumeAnnotationToken();

clang/lib/Sema/SemaDecl.cpp

@@ -20573,7 +20573,8 @@ TopLevelStmtDecl *Sema::ActOnStartTopLevelStmtDecl(Scope *S) {
 }
 
 void Sema::ActOnFinishTopLevelStmtDecl(TopLevelStmtDecl *D, Stmt *Statement) {
-  D->setStmt(Statement);
+  if (Statement)
+    D->setStmt(Statement);
   PopCompoundScope();
   PopFunctionScopeInfo();
   PopDeclContext();

clang/test/Interpreter/fail.cpp

@@ -18,4 +18,11 @@ extern "C" int printf(const char *, ...);
 int i = 42;
 auto r1 = printf("i = %d\n", i);
 // CHECK: i = 42
+
+1aap = 42; // expected-error {{invalid digit 'a' in decimal constant}}
+1aap = 42; i = 5; // expected-error {{invalid digit 'a' in decimal constant}}
+
+printf("i = %d\n", i);
+// CHECK: i = 42
+
 %quit