Summary: public
C++ assignment operation result is lvalue, while in C it was rvalue.
This leads to different AST produced by clang for then same code!
Use language information from clang (`-x` flag) to distinguish these cases.
More specifically, let's look at following code:
int r;
int f = (r = 3);
// type of (r = 3) expression:
// C/objC -> int rvalue
// C++/objC++ -> int lvalue
Existing code did extra dereference because it was rvalue in C and there was no cast afterwards
in C++ there will be extra LValueToRvalue cast when neccesary so we don't have to do extra dereference manually
Reference:
http://en.cppreference.com/w/c/language/value_category (search for 'assignment and compound assignment operators')
NOTE: AST output doesn't change when something is hidden behind `extern "C"`, so we should use global language information
Reviewed By: ddino
Differential Revision: D2549866
fb-gh-sync-id: b193b11
Summary: public Two cases were not handled properly so far:
1. Declaration of a reference variable missed reference bit in type
2. Parameters to a function expecting T& had type T.
The way to distinguish reference types from value types is to look
whether parameter is type 'T rvalue' or type 'T lvalue' (xvalue probably as well)
Unfortunately, we can't just say 'T lvalue' = 'T&' because it would break
a lot of things in our frontend.
However, we know that when parameter to a function call has type 'T lvalue', it has to be 'T&' type.
Same applies when init_expression type is lvalue.
So, the solution is to add wrapper function that looks at results of `instruction` function and
expected expression type. Then if it's lvalue, wrap the type in reference.
Do this wrapping magic only when we know that lvalue mean reference type.
The rest of the changes is to make frontend tests pass - since we use different fields
in the AST, some of them were incorrectly set before and no one noticed.
Reviewed By: cristianoc
Differential Revision: D2549991
fb-gh-sync-id: 067f5d5
Summary: @public
This diff changes following things:
1. expression_info.type_ptr has type than decl_ref_info.type_ptr for reference types. Use type from decl_ref_info as a source of truth
2. reference types need to have one extra dereference that is not in AST. Add handling for this.
3. [small refactor] create function that creates temporary variable from res_trans expression and returns new res_trans.
Some caveats:
1. types are not quite right yet (see .dot files).
2. decl_ref_info might not be set for DeclRefExpr, make frontend crash in that case to catch when this happens
This is high risk change since it changes behavior of every translation on very widely used expr.
Reviewed By: @dulmarod
Differential Revision: D2540632
fb-gh-sync-id: aa28936
Andrzej Kotulski