[PATCH] D68751: [lld][WebAssembly] Where possible handle signature mismatches via an adaptor function

Wed Oct 9 20:49:31 PDT 2019

ruiu added inline comments.

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Comment at: lld/wasm/SymbolTable.cpp:592
+// types don't match the adaptor creation will tail.
+bool SymbolTable::replaceWithAdaptorFunction(FunctionSymbol *sym,
+                                             FunctionSymbol *target) {
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sbc100 wrote:
> ruiu wrote:
> > This function seems to enables to call an external function with a less number of arguments. I wonder what is the use case of this -- as long as you have a correct header file for functions, compilers can tell users that the number of parameters doesn't match.
> Yes, normally this shouldn't happen, but sadly there are some cases in C when it does.
> 
> The motivating case here is crt1.c calling the main function from _start.   We want to be able support both 3 argument and 2 arguments forms.   With native linking you can simply link these two together it will kind of "just work".   With wasm, before this change we end up generating a linker warning and _start ends up calling stub function, so the program doesn't work.
> 
> This change fixes that use case.
I'm curious if it makes sense to limit this functionality only to "main" if there's no other use cases, so that we don't accidentally link a wrong program as if it were a correct one. What do you think?

Repository:
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CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D68751/new/

https://reviews.llvm.org/D68751