[all-commits] [llvm/llvm-project] 994c07: [Sema][SVE] Reject arrays of sizeless types

[rsandifo-arm via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 994c071a1b7eee8de132d78286c730da2be2c48f
      https://github.com/llvm/llvm-project/commit/994c071a1b7eee8de132d78286c730da2be2c48f
  Author: Richard Sandiford <richard.sandiford at arm.com>
  Date:   2020-03-13 (Fri, 13 Mar 2020)

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

  Log Message:
  -----------
  [Sema][SVE] Reject arrays of 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.

Differential Revision: https://reviews.llvm.org/D76082