Fix Loc-related crash in definition_validator (#7454)

* Add failing test

    ❯ sorbet test/testdata/definition_validator/superclass_class_loc__1.rb test/testdata/definition_validator/superclass_class_loc__2.rbi
    msg="Bad offset2Pos off" path="test/testdata/definition_validator/superclass_class_loc__1.rb" off="778""
    source="# typed: true\n\nmodule Parent\nend\n\nclass Child < Parent\nend\n"
    Exception::raise(): core/Loc.cc:43 enforced condition false has failed: (no message provided)

    Backtrace:
      #3 0xbb3f32
      #4 0x1a5b870 sorbet::core::Loc::offset2Pos()
      #5 0x1a5bbda sorbet::core::Loc::position()
      #6 0x1a5da17 sorbet::core::Loc::filePosToString()
      #7 0x19df6b8 sorbet::core::Error::toString()
      #8 0x19f292e sorbet::core::ErrorQueue::pushError()
      #9 0x1a3e882 sorbet::core::GlobalState::_error()
      #10 0x19e11c0 sorbet::core::ErrorBuilder::~ErrorBuilder()
      #11 0x1288d5a sorbet::definition_validator::(anonymous namespace)::validateSuperClass()
      #12 0x12861b6 sorbet::definition_validator::(anonymous namespace)::ValidateWalk::preTransformClassDef()
      #13 0x1285f6a sorbet::ast::MapFunctions<>::CALL_MEMBER_impl_preTransformClassDef<>::call<>()
      #14 0x1284c0f sorbet::ast::TreeMapper<>::mapClassDef()
      #15 0x1283d55 sorbet::ast::TreeMapper<>::mapIt()
      #16 0x1285a58 sorbet::ast::TreeMapper<>::mapInsSeq()
      #17 0x12846a6 sorbet::ast::TreeMapper<>::mapIt()
      #18 0x12839fa sorbet::ast::TreeWalk::apply<>()
      #19 0x12838db sorbet::definition_validator::runOne()
      #20 0xf5e8b0 sorbet::realmain::pipeline::(anonymous namespace)::typecheckOne()
      #21 0xf5e50d sorbet::realmain::pipeline::typecheck()::$_5::operator()()
      #22 0xf5e19d std::__1::__invoke<>()
      #23 0xf5e14d std::__1::__invoke_void_return_wrapper<>::__call<>()
      #24 0xf5e11d std::__1::__function::__alloc_func<>::operator()()
      #25 0xf5d2e9 std::__1::__function::__func<>::operator()()
      #26 0x1753d52 std::__1::__function::__value_func<>::operator()()
      #27 0x174a5f5 std::__1::function<>::operator()()
      #28 0x1bf5d7a sorbet::WorkerPoolImpl::multiplexJob()::$_2::operator()()
      #29 0x1bf5d1d std::__1::__invoke<>()
      #30 0x1bf5ccd std::__1::__invoke_void_return_wrapper<>::__call<>()
      #31 0x1bf5c9d std::__1::__function::__alloc_func<>::operator()()
      #32 0x1bf4ea9 std::__1::__function::__func<>::operator()()
      #33 0x1bfa5b2 std::__1::__function::__value_func<>::operator()()
      #34 0x1bf91d5 std::__1::function<>::operator()()
      #35 0x1bf313d sorbet::WorkerPoolImpl::WorkerPoolImpl()::$_0::operator()()
      #36 0x1bf307d std::__1::__invoke<>()
      #37 0x1bf302d std::__1::__invoke_void_return_wrapper<>::__call<>()
      #38 0x1bf2ffd std::__1::__function::__alloc_func<>::operator()()
      #39 0x1bf2219 std::__1::__function::__func<>::operator()()
      #40 0x1753d52 std::__1::__function::__value_func<>::operator()()
      #41 0x174a5f5 std::__1::function<>::operator()()
      #42 0x1bfdd53 Joinable::trampoline()
      #43 0x7f5e1d694b43
      #44 0x7f5e1d726a00

* Fix failing test

Author: jez

definition_validator/validator.cc

@@ -740,8 +740,7 @@ void validateSuperClass(core::Context ctx, const core::ClassOrModuleRef sym, con
         return;
     }
 
-    if (auto e = ctx.state.beginError(core::Loc(sym.data(ctx)->loc().file(), classDef.declLoc),
-                                      core::errors::Resolver::NonClassSuperclass)) {
+    if (auto e = ctx.state.beginError(ctx.locAt(classDef.declLoc), core::errors::Resolver::NonClassSuperclass)) {
         auto superClassFqn = superClass.show(ctx);
         e.setHeader("The super class `{}` of `{}` does not derive from `{}`", superClassFqn, sym.show(ctx),
                     core::Symbols::Class().show(ctx));

test/testdata/definition_validator/superclass_class_loc__1.rb

@@ -0,0 +1,7 @@
+# typed: true
+
+module Parent
+end
+
+class Child < Parent # error: does not derive from `Class`
+end

test/testdata/definition_validator/superclass_class_loc__2.rbi

@@ -0,0 +1,18 @@
+# typed: true
+
+# This is a rather large comment at the start of the file which exposes a bug
+# where we were accidentally turning a LocOffset from this file into a Loc for
+# the other file. With a sufficiently long comment, that causes an array access
+# out of bounds.
+# This is a rather large comment at the start of the file which exposes a bug
+# where we were accidentally turning a LocOffset from this file into a Loc for
+# the other file. With a sufficiently long comment, that causes an array access
+# out of bounds.
+# This is a rather large comment at the start of the file which exposes a bug
+# where we were accidentally turning a LocOffset from this file into a Loc for
+# the other file. With a sufficiently long comment, that causes an array access
+# out of bounds.
+
+class Child < Parent # error: does not derive from `Class`
+  def example; end
+end