[TCling] Add test for #8367

Author: dpiparo

core/metacling/test/TClingTests.cxx

@@ -409,3 +409,16 @@ const Constructor c19(19);
       EXPECT_EQ(constructors[i], i);
    }
 }
+
+// #8367
+TEST_F(TClingTests, UndeclaredIdentifierCrash)
+{
+   auto expectedError = R"(input_line_30:2:11: error: use of undeclared identifier 'i'
+ for(i=0; i < 0;); // the second usage of `i` was enough to get a segfault
+          ^
+)";
+   using namespace ROOT::TestSupport;
+   CheckDiagsRAII diagRAII;
+   diagRAII.requiredDiag(kError, "cling", expectedError, false);
+   gInterpreter->ProcessLine("for(i=0; i < 0;); // the second usage of `i` was enough to get a segfault");
+}