Fix a basic bug (having to do with typedefs) in Sema::UsualArithmeticConversions(). 

This resuled in the following crash below.

Also modified the usual-float.c test case to capture this case.

[steve-naroffs-imac:clang/test/Sema] snaroff% ../../../../Debug/bin/clang usual-float.c
Assertion failed: (0 && "Sema::UsualArithmeticConversions(): illegal float comparison"), function UsualArithmeticConversions, file SemaExpr.cpp, line 960.
0   clang                               0x001ef9b9 _ZN40_GLOBAL__N_Signals.cpp_00000000_4E6DAF8315PrintStackTraceEv + 45
1   clang                               0x001efd5f _ZN40_GLOBAL__N_Signals.cpp_00000000_4E6DAF8313SignalHandlerEi + 323
2   libSystem.B.dylib                   0x90c6297b _sigtramp + 43
3   ???                                 0xffffffff 0x0 + 4294967295
4   libSystem.B.dylib                   0x90cdb782 raise + 26
5   libSystem.B.dylib                   0x90cead3f abort + 73
6   libSystem.B.dylib                   0x90cdc923 __assert_rtn + 101
7   clang                               0x00077316 _ZN5clang4Sema26UsualArithmeticConversionsERPNS_4ExprES3_b + 1004
8   clang                               0x000803cf _ZN5clang4Sema27CheckMultiplyDivideOperandsERPNS_4ExprES3_NS_14SourceLocationEb + 181
9   clang                               0x0007a8e8 _ZN5clang4Sema10ActOnBinOpENS_14SourceLocationENS_3tok9TokenKindEPvS4_ + 472
10  clang                               0x000cf058 _ZN5clang6Parser26ParseRHSOfBinaryExpressionENS_6Action12ActionResultILj0EEEj + 1286
11  clang                               0x000cf2de _ZN5clang6Parser25ParseAssignmentExpressionEv + 86



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@43985 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed