From ea9c68353e04513d806035f75b03e39e75b0737b Mon Sep 17 00:00:00 2001
From: 0-v-0 <kduice@qq.com>
Date: Tue, 30 Jun 2026 14:26:03 +0800
Subject: [PATCH] Fix #18981 - Propagate TemplateThisParameter through
 inheritance

---
 compiler/src/dmd/expressionsem.d     |  5 +++--
 compiler/test/compilable/test14484.d | 17 +++++++++++++++++
 2 files changed, 20 insertions(+), 2 deletions(-)
 create mode 100644 compiler/test/compilable/test14484.d

diff --git a/compiler/src/dmd/expressionsem.d b/compiler/src/dmd/expressionsem.d
index 995a003aad96..ec79d1ef3991 100644
--- a/compiler/src/dmd/expressionsem.d
+++ b/compiler/src/dmd/expressionsem.d
@@ -8373,13 +8373,14 @@ private extern (C++) final class ExpressionSemanticVisitor : Visitor
             {
                 s = (cast(TemplateExp)exp.e1).td;
             L2:
-                exp.f = resolveFuncCall(exp.loc, sc, s, tiargs, null, exp.argumentList,
+                auto fdthis = hasThis(sc);
+                exp.f = resolveFuncCall(exp.loc, sc, s, tiargs, fdthis ? fdthis.vthis.type : null, exp.argumentList,
                     exp.isUfcsRewrite ? FuncResolveFlag.ufcs : FuncResolveFlag.standard);
                 if (!exp.f || exp.f.errors)
                     return setError();
                 if (exp.f.needThis())
                 {
-                    if (hasThis(sc))
+                    if (fdthis)
                     {
                         // Supply an implicit 'this', as in
                         //    this.ident
diff --git a/compiler/test/compilable/test14484.d b/compiler/test/compilable/test14484.d
new file mode 100644
index 000000000000..da2a68e181fb
--- /dev/null
+++ b/compiler/test/compilable/test14484.d
@@ -0,0 +1,17 @@
+// https://issues.dlang.org/show_bug.cgi?id=14484
+
+class A
+{
+    final void f(this This)()
+    {
+        static assert(This.stringof == "B");
+    }
+}
+
+class B : A
+{
+    void x()
+    {
+        f();
+    }
+}