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add RefCast to Expressions #4164

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add RefCast to Expressions #4164

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24 changes: 21 additions & 3 deletions spec/expression.dd
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Original file line number Diff line number Diff line change
Expand Up @@ -1199,7 +1199,8 @@ $(H3 $(LNAME2 cast_expressions, Cast Expressions))
$(GRAMMAR
$(GNAME CastExpression):
$(D cast $(LPAREN)) $(GLINK2 type, Type) $(D $(RPAREN)) $(GLINK UnaryExpression)
$(GLINK CastQual)
$(GLINK RefCast)
$(GLINK QualifierCast)
)

$(P A $(I CastExpression) converts the $(I UnaryExpression)
Expand Down Expand Up @@ -1598,14 +1599,31 @@ $(H4 $(LNAME2 cast_struct, Structs))
---
)

$(H4 $(LNAME2 refcast, Reference Cast))

$(GRAMMAR
$(GNAME RefCast):
$(D cast $(LPAREN)) $(D ref) $(GLINK2 type, Type) $(D $(RPAREN)) $(GLINK UnaryExpression)
)

$(P A $(I RefCast) takes a $(I UnaryExpression) representing an lvalue and forcibly changes
its type to $(I Type). It is equivalent to the expression $(D *cast(Type*)&UnaryExpression).
)

---
int i = 73;
float f = *cast(float*)&i; // reinterprets the integer bit pattern as a float
float g = cast(ref float)i; // equivalent to the previous statement
---

$(H4 $(LNAME2 cast_qualifier, Qualifier Cast))

$(GRAMMAR
$(GNAME CastQual):
$(GNAME QualifierCast):
$(D cast $(LPAREN)) $(GLINK2 type, TypeCtors)$(OPT) $(D $(RPAREN)) $(GLINK UnaryExpression)
)

$(P A $(I CastQual) replaces the qualifiers in the type of
$(P A $(I QualifierCast) replaces the qualifiers in the type of
the $(I UnaryExpression):)

$(SPEC_RUNNABLE_EXAMPLE_COMPILE
Expand Down