[PATCH] D123955: [C2x] Disallow functions without prototypes/functions with identifier lists

Tom Honermann via Phabricator via cfe-commits cfe-commits at lists.llvm.org
Mon Apr 18 13:31:23 PDT 2022

tahonermann added inline comments.

Comment at: clang/lib/StaticAnalyzer/Core/MemRegion.cpp:1034-1042
+          if (T.isNull() || !T->getAs<FunctionType>())
+            // If the type is invalid or is not a function type, we cannot get
+            // a block pointer type for it. This isn't ideal, but it's better
+            // than asserting in getBlockPointerType() or creating a function
+            // without a prototype in a language that has no such concept (like
+            // C++ or C2x).
+            sReg = getUnknownRegion();
rsmith wrote:
> I find it really surprising that the "signature is present but is not a function type" case is reachable -- the static analyzer should only run on valid code, and in valid code I'd expect the signature of a block would always be a function type. Is that  case actually reached in our test suite?
> I worry that the "block has no explicit signature" case here is common, and that we're losing substantial coverage in that case. Per https://clang.llvm.org/docs/BlockLanguageSpec.html#block-literal-expressions, `^ {  ...  }` is equivalent  to `^ (void) { ... }`, so it seems the original code here was just wrong and we should always have been creating a `FunctionProtoType`  in this case.
I haven't studied the surrounding code much, so perhaps this comment isn't applicable, but I would expect `FunctionProtoType` to be applicable when an empty parameter list is explicitly specified as in `^ () { ... }` prior to C2x.



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