Merge pull request #1685 from AndrejMitrovic/Fix9574

Issue 9574 - Better diagnostic on old 'alias this = that' syntax.
dlang · Mar 7, 2013 · 1e9511b · 1e9511b
2 parents 0679c4c + 9b3ecfb
commit 1e9511b
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Showing 2 changed files with 31 additions and 3 deletions.
diff --git a/src/parse.c b/src/parse.c
@@ -3121,7 +3121,8 @@ Dsymbols *Parser::parseDeclarations(StorageClass storage_class, unsigned char *c
         else if (t != tfirst)
             error("multiple declarations must have the same type, not %s and %s",
                 tfirst->toChars(), t->toChars());
-        if (!ident)
+        bool isThis = (t->ty == Tident && ((TypeIdentifier *)t)->ident == Id::This);
+        if (!isThis && !ident)
             error("no identifier for declarator %s", t->toChars());
 
         if (tok == TOKtypedef || tok == TOKalias)
@@ -3146,8 +3147,16 @@ Dsymbols *Parser::parseDeclarations(StorageClass storage_class, unsigned char *c
                 deprecation("use of typedef is deprecated; use alias instead");
             }
             else
-            {   if (init)
-                    error("alias cannot have initializer");
+            {
+                if (init)
+                {
+                    if (isThis)
+                        error("Cannot use syntax 'alias this = %s', use 'alias %s this' instead",
+                           init->toChars(), init->toChars());
+                    else
+                        error("alias cannot have initializer");
+                }
+
                 v = new AliasDeclaration(loc, ident, t);
             }
             v->storage_class = storage_class;

diff --git a/test/fail_compilation/diag9574.d b/test/fail_compilation/diag9574.d
@@ -0,0 +1,19 @@
+/*
+TEST_OUTPUT:
+---
+fail_compilation/diag9574.d(12): Error: Cannot use syntax 'alias this = x', use 'alias x this' instead
+fail_compilation/diag9574.d(18): Error: Cannot use syntax 'alias this = x', use 'alias x this' instead
+---
+*/
+
+struct S
+{
+    int x;
+    alias this = x;
+}
+
+class C
+{
+    int x;
+    alias this = x;
+}