Merge pull request #2485 from WalterBright/mixin-args

fix Issue 19292 - Mixin expressions should take an argument list

spec/expression.dd

@@ -1728,18 +1728,20 @@ $(H3 $(LNAME2 mixin_expressions, Mixin Expressions))
 
 $(GRAMMAR
 $(GNAME MixinExpression):
-    $(D mixin $(LPAREN)) $(GLINK AssignExpression) $(D $(RPAREN))
+    $(D mixin $(LPAREN)) $(GLINK ArgumentList) $(D $(RPAREN))
 )
 
-    $(P The $(I AssignExpression) must evaluate at compile time
-        to a constant string.
+    $(P Each $(GLINK AssignExpression) in the $(I ArgumentList) is
+        evaluated at compile time, and the result must be representable
+        as a string.
+        The resulting strings are concatenated to form a string.
         The text contents of the string must be compilable as a valid
-        $(I Expression), and is compiled as such.)
+        $(GLINK Expression), and is compiled as such.)
 
         ---
         int foo(int x)
         {
-            return mixin("x + 1") * 7;  // same as ((x + 1) * 7)
+            return mixin("x +", 1) * 7;  // same as ((x + 1) * 7)
         }
         ---
 

spec/module.dd

@@ -623,12 +623,17 @@ $(H2 $(LEGACY_LNAME2 MixinDeclaration, mixin-declaration, Mixin Declaration))
 
 $(GRAMMAR
 $(GNAME MixinDeclaration):
-    $(D mixin) $(D $(LPAREN)) $(ASSIGNEXPRESSION) $(D $(RPAREN)) $(D ;)
+    $(D mixin) $(D $(LPAREN)) $(GLINK2 expression, ArgumentList) $(D $(RPAREN)) $(D ;)
 )
 
-$(P The $(ASSIGNEXPRESSION) must evaluate at compile time to a constant string.
-The text contents of the string must be compilable as a valid $(GLINK DeclDefs),
-and is compiled as such.)
+    $(P Each $(GLINK2 expression, AssignExpression) in the $(I ArgumentList) is
+        evaluated at compile time, and the result must be representable
+        as a string.
+        The resulting strings are concatenated to form a string.
+        The text contents of the string must be compilable as a valid
+        $(GLINK DeclDefs), and is compiled as such.
+        )
+
 
 $(H2 $(LEGACY_LNAME2 PackageModule, package-module, Package Module))
 

spec/statement.dd

@@ -1866,11 +1866,13 @@ $(H2 $(LEGACY_LNAME2 MixinStatement, mixin-statement, Mixin Statement))
 
 $(GRAMMAR
 $(GNAME MixinStatement):
-    $(D mixin) $(D $(LPAREN)) $(ASSIGNEXPRESSION) $(D $(RPAREN)) $(D ;)
+    $(D mixin) $(D $(LPAREN)) $(GLINK2 expression, ArgumentList) $(D $(RPAREN)) $(D ;)
 )
 
-        $(P The $(ASSIGNEXPRESSION) must evaluate at compile time
-        to a constant string.
+    $(P Each $(GLINK2 expression, AssignExpression) in the $(I ArgumentList) is
+        evaluated at compile time, and the result must be representable
+        as a string.
+        The resulting strings are concatenated to form a string.
         The text contents of the string must be compilable as a valid
         $(GLINK StatementList), and is compiled as such.
         )
@@ -1897,6 +1899,8 @@ void main()
     mixin("y =") 4; // error, string must be complete statement
 
     mixin("y =" ~ "4;");  // ok
+
+    mixin("y =", 2+2, ";");  // ok
 }
 ---