Fix loplugin:trivialconstructor handling of ctor templates

Change-Id: Ic8b2f26498099c77b834d8e152f06d2834dfee3a
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/131658
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

2 files changed, 58 insertions, 4 deletions

diff --git a/compilerplugins/clang/test/trivialconstructor.cxx b/compilerplugins/clang/test/trivialconstructor.cxx
new file mode 100644
index 000000000000..ef17e9c60fee
--- /dev/null
+++ b/compilerplugins/clang/test/trivialconstructor.cxx
@@ -0,0 +1,46 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+struct S1
+{
+    // expected-error@+1 {{no need for explicit constructor decl [loplugin:trivialconstructor]}}
+    S1() {}
+};
+
+struct S2
+{
+    S2() {}
+    S2(int) {}
+};
+
+struct S3
+{
+    S3() {}
+    template <typename T> S3(T);
+};
+
+template <typename> struct S4
+{
+    // expected-error@+1 {{no need for explicit constructor decl [loplugin:trivialconstructor]}}
+    S4() {}
+};
+
+template <typename> struct S5
+{
+    S5() {}
+    S5(int);
+};
+
+template <typename> struct S6
+{
+    S6() {}
+    template <typename T> S6(T);
+};
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */
diff --git a/compilerplugins/clang/trivialconstructor.cxx b/compilerplugins/clang/trivialconstructor.cxx
index 6f5bb640b760..dd830058fac9 100644
--- a/compilerplugins/clang/trivialconstructor.cxx
+++ b/compilerplugins/clang/trivialconstructor.cxx
@@ -65,13 +65,21 @@ bool TrivialConstructor::VisitCXXConstructorDecl(CXXConstructorDecl const* const
     const CXXRecordDecl* recordDecl = constructorDecl->getParent();
     if (std::distance(recordDecl->ctor_begin(), recordDecl->ctor_end()) != 1)
         return true;
+    // Constructor templates are not included in ctor_begin()..ctor_end() above, so also do a slow
+    // check across all decls():
+    for (auto d : recordDecl->decls())
+    {
+        if (auto const d2 = dyn_cast<FunctionTemplateDecl>(d))
+        {
+            if (isa<CXXConstructorDecl>(d2->getTemplatedDecl()))
+            {
+                return true;
+            }
+        }
+    }
     if (!HasTrivialConstructorBody(recordDecl, recordDecl))
         return true;
 
-    // template magic in sc/inc/stlalgorithm.hxx
-    if (recordDecl->getIdentifier() && recordDecl->getName() == "AlignedAllocator")
-        return true;
-
     report(DiagnosticsEngine::Warning, "no need for explicit constructor decl",
            constructorDecl->getLocation())
         << constructorDecl->getSourceRange();