Fix bugzilla 24883 - Speculative template overload error escapes with…

… `-preview=rvaluerefparam`
dlang · Nov 26, 2024 · 7d282bd · 7d282bd
1 parent 519d388
commit 7d282bd
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Showing 2 changed files with 13 additions and 1 deletion.
diff --git a/compiler/src/dmd/templatesem.d b/compiler/src/dmd/templatesem.d
@@ -1252,7 +1252,13 @@ extern (D) MATCHpair deduceFunctionTemplateMatch(TemplateDeclaration td, Templat
                 //printf("farg = %s %s\n", farg.type.toChars(), farg.toChars());
 
                 RootObject oarg = farg;
-                if ((fparam.storageClass & STC.ref_) && (!(fparam.storageClass & STC.auto_) || farg.isLvalue()))
+
+                if (farg.isFuncExp())
+                {
+                    // When assigning an untyped (void) lambda `x => y` to a `(F)(ref F)` parameter,
+                    // we don't want to deduce type void creating a void parameter
+                }
+                else if ((fparam.storageClass & STC.ref_) && (!(fparam.storageClass & STC.auto_) || farg.isLvalue()))
                 {
                     /* Allow expressions that have CT-known boundaries and type [] to match with [dim]
                      */

diff --git a/compiler/test/compilable/rvalueref.d b/compiler/test/compilable/rvalueref.d
@@ -11,3 +11,9 @@ struct AS
 
 void popFront(ref string) { }
 static assert(!is(typeof((R r) => r.popFront)));
+
+// https://issues.dlang.org/show_bug.cgi?id=24883
+int toString(Writer)(ref Writer sink) => 3;
+int toString(void delegate(scope const(char)[]) sink) => 4;
+void put() {}
+pragma(msg, toString(dst => put()));