[PATCH] D76082: [Sema][SVE] Reject arrays of sizeless types

[Richard Sandiford via Phabricator via cfe-commits]

rsandifo-arm created this revision.
rsandifo-arm added reviewers: sdesmalen, efriedma, rovka, rjmccall.
Herald added subscribers: cfe-commits, psnobl, rkruppe, tschuett.
Herald added a reviewer: rengolin.
Herald added a project: clang.
rsandifo-arm added a parent revision: D75738: [Sema][SVE] Reject by-copy capture of sizeless types.
rsandifo-arm added a child revision: D76084: [Sema][SVE] Reject subscripts on pointers to sizeless types.

The SVE ACLE doesn't allow arrays of sizeless types.  At the moment
clang accepts the TU:

  __SVInt8_t x[2];

but trying to code-generate it triggers the LLVM assertion:

  llvm/lib/IR/Type.cpp:588: static llvm::ArrayType* llvm::ArrayType::get(llvm::Type*, uint64_t): Assertion `isValidElementType(ElementType) && "Invalid type for array element!"' failed.

This patch reports an appropriate error instead.

The rules are slightly more restrictive than for general incomplete types.
For example:

  struct s;
  typedef struct s arr[2];

is valid as far as it goes, whereas arrays of sizeless types are
invalid in all contexts.  BuildArrayType therefore needs a specific
check for isSizelessType in addition to the usual handling of
incomplete types.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D76082

Files:
  clang/include/clang/Basic/DiagnosticSemaKinds.td
  clang/lib/Sema/SemaDecl.cpp
  clang/lib/Sema/SemaExpr.cpp
  clang/lib/Sema/SemaType.cpp
  clang/test/Sema/sizeless-1.c
  clang/test/SemaCXX/sizeless-1.cpp

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