Fix issue 18242 - Warn if object.Exception is missing

[LemonBoy]

Let's not segfault if no Exception class is defined.

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Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	18242	blocker	DMD Segmentation fault.

⚠️⚠️⚠️ Warnings ⚠️⚠️⚠️

• Regression or critical bug fixes should always target the stable branch. Learn more about rebasing to stable or the D release process.

[wilzbach]

How about adding a test like it was done in #7799 or #7786?

[JinShil]

If Throwable is declared, but Exception isn't, one should still be able to use try-catch statements. I think the fix should be placed elsewhere where the Exception symbol/identifier is used (perhaps when searching the symbol table for Exception, or in the semantic processing of Identifier or IdentifierExp). It should behave exactly like any other undefined identifier.

[WalterBright]

When creating a PR to fix a bugzilla issue, please post a link to the PR in the issue. This is so that someone browsing bug reports will know if and where a PR for it is. I did it for this one.

[jacob-carlborg]

When creating a PR to fix a bugzilla issue, please post a link to the PR in the issue. This is so that someone browsing bug reports will know if and where a PR for it is. I did it for this one.

Isn’t there a bot that does this automatically?

[LemonBoy]

I think the fix should be placed elsewhere where the Exception symbol/identifier is used

Let's try with this other approach then.

[WalterBright]

Isn’t there a bot that does this automatically?

No.

[wilzbach]

Isn’t there a bot that does this automatically?

dlang/dlang-bot#135

[JinShil]

I just tested this and it looks good to me. It just needs a test case.

[JinShil]

If you add DFLAGS: (without anything following it) it will prevent all the default flags for importing the runtime, etc.. from being added implicitly to compiler invocation. Then you shouldn't need to declare the TypeInfo stuff and have to deal with all the object mismatch errors.

See #7845

[JinShil]

Sorry, Ignore the comment above. It appears TypeInfo is required because Throwable has been declared. This should get you passed the 32-bit tests:

module object;

class Object { }

class Throwable { }

class TypeInfo { }
class TypeInfo_Class : TypeInfo 
{ 
    version(D_LP64)
    {
        ubyte[136] _x; 
    }
    else
    {
        ubyte[68] _x;
    }
}

int _d_run_main() 
{
    try { } catch(Throwable e) { return 1; }
    return 0;
}

[LemonBoy]

Thanks for the hint, I always forget about 32bit platforms.

[JinShil]

I think you need to remove the semicolon at the end of this line, and put it after the _x.

[JinShil]

I modified it (though I misspelled fix in the commit message) 😢