add __rvalue(expression) builtin

compiler/src/dmd/frontend.h

@@ -2068,6 +2068,7 @@ enum class EXP : uint8_t
     _Generic_ = 125u,
     interval = 126u,
     loweredAssignExp = 127u,
+    rvalue = 128u,
 };
 
 typedef uint64_t dinteger_t;
@@ -2888,33 +2889,34 @@ enum class TOK : uint8_t
     wchar_tLiteral = 196u,
     endOfLine = 197u,
     whitespace = 198u,
-    inline_ = 199u,
-    register_ = 200u,
-    restrict_ = 201u,
-    signed_ = 202u,
-    sizeof_ = 203u,
-    typedef_ = 204u,
-    unsigned_ = 205u,
-    volatile_ = 206u,
-    _Alignas_ = 207u,
-    _Alignof_ = 208u,
-    _Atomic_ = 209u,
-    _Bool_ = 210u,
-    _Complex_ = 211u,
-    _Generic_ = 212u,
-    _Imaginary_ = 213u,
-    _Noreturn_ = 214u,
-    _Static_assert_ = 215u,
-    _Thread_local_ = 216u,
-    _assert_ = 217u,
-    _import_ = 218u,
-    __cdecl_ = 219u,
-    __declspec_ = 220u,
-    __stdcall_ = 221u,
-    __thread_ = 222u,
-    __pragma_ = 223u,
-    __int128_ = 224u,
-    __attribute___ = 225u,
+    rvalue = 199u,
+    inline_ = 200u,
+    register_ = 201u,
+    restrict_ = 202u,
+    signed_ = 203u,
+    sizeof_ = 204u,
+    typedef_ = 205u,
+    unsigned_ = 206u,
+    volatile_ = 207u,
+    _Alignas_ = 208u,
+    _Alignof_ = 209u,
+    _Atomic_ = 210u,
+    _Bool_ = 211u,
+    _Complex_ = 212u,
+    _Generic_ = 213u,
+    _Imaginary_ = 214u,
+    _Noreturn_ = 215u,
+    _Static_assert_ = 216u,
+    _Thread_local_ = 217u,
+    _assert_ = 218u,
+    _import_ = 219u,
+    __cdecl_ = 220u,
+    __declspec_ = 221u,
+    __stdcall_ = 222u,
+    __thread_ = 223u,
+    __pragma_ = 224u,
+    __int128_ = 225u,
+    __attribute___ = 226u,
 };
 
 class FuncExp final : public Expression

compiler/src/dmd/parse.d

@@ -5877,6 +5877,7 @@ class Parser(AST, Lexer = dmd.lexer.Lexer) : Lexer
         case TOK.moduleString:
         case TOK.functionString:
         case TOK.prettyFunction:
+	case TOK.rvalue:
         Lexp:
             {
                 AST.Expression exp = parseExpression();
@@ -8410,6 +8411,15 @@ class Parser(AST, Lexer = dmd.lexer.Lexer) : Lexer
                 e = new AST.TypeidExp(loc, o);
                 break;
             }
+        case TOK.rvalue:
+            {
+                nextToken();
+                check(TOK.leftParenthesis, "`__rvalue`");
+                RootObject o = parseAssignExp();
+                check(TOK.rightParenthesis);
+                //e = new AST.RvalueExp(loc, o);
+                break;
+            }
         case TOK.traits:
             {
                 /* __traits(identifier, args...)
@@ -9711,6 +9721,7 @@ immutable PREC[EXP.max + 1] precedence =
     EXP.void_ : PREC.primary,
     EXP.vectorArray : PREC.primary,
     EXP._Generic : PREC.primary,
+    EXP.rvalue : PREC.primary,
 
     // post
     EXP.dotTemplateInstance : PREC.primary,

compiler/src/dmd/tokens.d

@@ -27,6 +27,8 @@ enum TOK : ubyte
 {
     reserved,
 
+    // if this list changes, update ../tests/cxxfrontend.cc and ../../test/unit/lexer/location_offset.d to match
+
     // Other
     leftParenthesis,
     rightParenthesis,
@@ -249,6 +251,7 @@ enum TOK : ubyte
     wchar_tLiteral,
     endOfLine,  // \n, \r, \u2028, \u2029
     whitespace,
+    rvalue,
 
     // C only keywords
     inline,
@@ -425,6 +428,7 @@ enum EXP : ubyte
     interval,
 
     loweredAssignExp,
+    rvalue,
 }
 
 enum FirstCKeyword = TOK.inline;
@@ -556,6 +560,7 @@ private immutable TOK[] keywords =
     TOK.prettyFunction,
     TOK.shared_,
     TOK.immutable_,
+    TOK.rvalue,
 
     // C only keywords
     TOK.inline,
@@ -680,6 +685,7 @@ extern (C++) struct Token
         TOK.pragma_: "pragma",
         TOK.typeof_: "typeof",
         TOK.typeid_: "typeid",
+        TOK.rvalue: "__rvalue",
         TOK.template_: "template",
         TOK.void_: "void",
         TOK.int8: "byte",

compiler/src/dmd/tokens.h

@@ -196,6 +196,7 @@ enum class TOK : unsigned char
     auto_,
     package_,
     immutable_,
+    rvalue,
 
     // Statements
     if_,

compiler/test/unit/lexer/location_offset.d

@@ -399,6 +399,7 @@ enum Test[string] tests = [
     "auto_" : Test("auto"),
     "package_" : Test("package"),
     "immutable_" : Test("immutable"),
+    "rvalue" : Test("__rvalue"),
 
     "if_" : Test("if"),
     "else_" : Test("else"),