[fuzz] Assertion `hasInClassInitializer() && InitStorage.getPointer() == nullptr && "bit width, initializer or captured type already set"' failed.

[llvmbot]

Bugzilla Link	21860
Resolution	FIXED
Resolved on	Oct 21, 2016 18:30
Version	trunk
OS	Linux
Blocks	#23431
Attachments	test case
Reporter	LLVM Bugzilla Contributor
CC	@majnemer,@DougGregor,@zygoloid,@rnk

Extended Description

Fuzzing discovered that the attached test case, when given as input to

clang -fno-crash-diagnostics -std=c++11 -xc++ -c -emit-llvm

causes this assertion failure:

clang-3.6: tools/clang/include/clang/AST/Decl.h:2299: void clang::FieldDecl::setInClassInitializer(clang::Expr *): Assertion `hasInClassInitializer() && InitStorage.getPointer() == nullptr && "bit width, initializer or captured type already set"' failed.

[majnemer]

cleaned up a bit:
template struct e {
operator int();
int np1 = e();
};
e a = e();

GCC and MSVC both accept (but generate code that may infinitely recurse).

[majnemer]

Richard, it looks like we keep instantiating the same template over and over again. Any ideas?

[rnk]

We now reject:

C:/Users/rnk/Downloads/funs-without-prototype.cpp:1:28: error: default member initializer for 'np1' uses itself
template struct e {
^
C:/Users/rnk/Downloads/funs-without-prototype.cpp:1:28: note: in instantiation of default member initializer 'e::np1' requested here
C:/Users/rnk/Downloads/funs-without-prototype.cpp:1:28: note: in instantiation of default member initializer 'e::np1' requested here
C:/Users/rnk/Downloads/funs-without-prototype.cpp:3:13: note: implicit default constructor for 'e' first required here
int np1 = e();
^
C:/Users/rnk/Downloads/funs-without-prototype.cpp:5:12: note: implicit default constructor for 'e' first required here
e a = e();
^

[kcc]

mentioned in issue #23431