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lvalue-to-rvalue conversion adjusts lvalues of qualified, non-class
type to rvalue expressions of the unqualified variant of that
type. For example, given:
const int i;
(void)(i + 17);
the lvalue-to-rvalue conversion for the subexpression "i" will turn it
from an lvalue expression (a DeclRefExpr) with type 'const int' into
an rvalue expression with type 'int'. Both C and C++ mandate this
conversion, and somehow we've slid through without implementing it.
We now have both DefaultFunctionArrayConversion and
DefaultFunctionArrayLvalueConversion, and which gets used depends on
whether we do the lvalue-to-rvalue conversion or not. Generally, we do
the lvalue-to-rvalue conversion, but there are a few notable
exceptions:
- the left-hand side of a '.' operator
- the left-hand side of an assignment
- a C++ throw expression
- a subscript expression that's subscripting a vector
Making this change exposed two issues with blocks:
- we were deducing const-qualified return types of non-class type
from a block return, which doesn't fit well
- we weren't always setting the known return type of a block when it
was provided with the ^return-type syntax
Fixes the current Clang-on-Clang compile failure and PR6076.
llvm-svn: 95167
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