clang::CompoundLiteralExpr::Init can be NULL, consequently getInitializer() must use cast_or_null.

[llvmbot]

Bugzilla Link	3269
Resolution	FIXED
Resolved on	Mar 12, 2010 00:59
Version	unspecified
OS	All
Reporter	LLVM Bugzilla Contributor
CC	@efriedma-quic

Extended Description

To see a case where CompoundLiteralExpr::Init is null:

• modify getSourceRange() adding `assert(Init && "Init CAN be null.");' as first line of the function body.
• compile clang
• exec the new clang with this code:
  ---->
  struct S {
  char a[2]; int b; };
  int f() {
  return __builtin_offsetof(struct S, b); }
  ----<

The assertion will fail, and since the compound literal do not actually have an init expression it is correct.
Yet, the getInitializer() functions use cast() that crashes in case of null pointers. It must be changed to cast_or_null.

[lattner]

You can also see this with -ast-dump:
clang bc.c -ast-dump
(CompoundStmt 0x20049d0 <bc.c:3:9, line:4:43>
(ReturnStmt 0x2004750 <col:3, col:39>
(ImplicitCastExpr 0x20049b0 <col:10, col:39> 'int'
(UnaryOperator 0x2004990 <col:10, col:39> 'unsigned long' prefix '__builtin_offsetof'
(MemberExpr 0x2004970 <:0:0, bc.c:4:39> 'int' .b 0x2004880
(CompoundLiteralExpr 0x2004930 <:0:0> 'struct S'
<<>>))))))

Personally, I think the real fix is to make the CompoundLiteralExpr have a non-null pointer (e.g. an empty initlistexpr).

[efriedma-quic]

Fixed in r62981, by eliminating the case where the initializer for a compound literal could be null.