Vector35 / Vector35/binaryninja-api

scc unions in structs

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Component: SCC Impact: Low
Dominant language
C++
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Merged PRs (30d)
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Description

struct a {
	union {
		int b;
		int c;
	} d;
};

int main (struct a * e) {
	return e->d.b;
}

For x86_64 linux in scc, the above code gives:

error: unable to generate code for IL: var<@t0> = var<e>->a::d

FYI, the following does seem to work:

struct a {
	union {
		int b;
		int c;
	} d;
};

int main () {
	struct a e;
	return e.d.b;
}

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  4. Open a pull request that references the issue number.

Research direction

Reproduce the x86_64 Linux failure with the first C example and compare it with the working local-union example. Inspect the scc compiler's code generation for pointer access to a struct containing a union; done when the failing example compiles without the IL generation error and the working example remains successful.

Written by the indexing model from the issue text.

Assessment

Tech stack
c
Domain
compilers
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
42/100

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