Fix SILVerifier assert for witness_method with dynamic self type

[meg-gupta]

Fixes rdar://71290925

[meg-gupta]

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[slavapestov]

Should we instead try to fix this to work? What goes wrong if such a witness_method instruction is generated?

[aschwaighofer]

We hit the SIL verifier not liking such a witness method instruction. It only wants opened archetype type operands.

void checkWitnessMethodInst(WitnessMethodInst *AMI) {  
    auto lookupType = AMI->getLookupType();                                     
    if (getOpenedArchetypeOf(lookupType)) {                                     
      require(AMI->getTypeDependentOperands().size() == 1,                      
              "Must have a type dependent operand for the opened archetype");   
      verifyOpenedArchetype(AMI, lookupType);                                   
    } else {                                                                    
      require(AMI->getTypeDependentOperands().empty(),                          
              "Should not have an operand for the opened existential");         
    } 

[swift-ci]

Build failed
Swift Test Linux Platform
Git Sha - de957f86e97716e4304bc84a810972a67003d600

[meg-gupta]

I changed what this PR was initially intended for. Turns out we do support witness_method with dynamic_self. The SILVerifier assertions for witness_method needed to be changed

[meg-gupta]

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[swift-ci]

Build failed
Swift Test OS X Platform
Git Sha - de957f86e97716e4304bc84a810972a67003d600

[meg-gupta]

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[meg-gupta]

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[slavapestov]

Thanks, changing the verifier here makes sense. We do support witness_method on concrete types just fine (either in IRGen, or the devirtualizer if that gets to run)

[meg-gupta]

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