[Clang][Sema] Warn when function argument is less aligned than parameter

See https://bugs.llvm.org/show_bug.cgi?id=42154.

GCC's __attribute__((align)) can reduce the alignment of a type when applied to
a typedef.  However, functions which take a pointer or reference to the
original type are compiled assuming the original alignment.  Therefore when any
such function is passed an object of the new, less-aligned type, an alignment
fault can occur.  In particular, this applies to the constructor, which is
defined for the original type and called for the less-aligned object.

This change adds a warning whenever an pointer or reference to an object is
passed to a function that was defined for a more-aligned type.

The calls to ASTContext::getTypeAlignInChars seem change the order in which
record layouts are evaluated, which caused changes to the output of
-fdump-record-layouts. As such some tests needed to be updated:

  * Use CHECK-LABEL rather than counting the number of "Dumping AST Record
    Layout" headers.

  * Check for end of line in labels, so that struct B1 doesn't match struct B
    etc.

  * Add --strict-whitespace, since the whitespace shows meaningful structure.

  * The order in which record layouts are printed has changed in some cases.

  * clang-format for regions changed

Differential Revision: https://reviews.llvm.org/D97187

0 files changed, 0 insertions, 0 deletions