C++: fix hasImplicitCopyConstructor for templates

cpp/ql/lib/change-notes/2022-03-10-template-implicit-copy.md

@@ -0,0 +1,4 @@
+---
+category: minorAnalysis
+---
+* `hasImplicitCopyConstructor` and `hasImplicitCopyAssignmentOperator` now correctly handle implicitly-deleted operators in templates.

cpp/ql/lib/semmle/code/cpp/Class.qll

@@ -286,6 +286,16 @@ class Class extends UserType {
     not this.implicitCopyConstructorDeleted() and
     forall(CopyConstructor cc | cc = this.getAMemberFunction() |
       cc.isCompilerGenerated() and not cc.isDeleted()
+    ) and
+    (
+      not this instanceof ClassTemplateInstantiation
+      or
+      this.(ClassTemplateInstantiation).getTemplate().hasImplicitCopyConstructor()
+    ) and
+    (
+      not this instanceof PartialClassTemplateSpecialization
+      or
+      this.(PartialClassTemplateSpecialization).getPrimaryTemplate().hasImplicitCopyConstructor()
     )
   }
 
@@ -301,6 +311,18 @@ class Class extends UserType {
     not this.implicitCopyAssignmentOperatorDeleted() and
     forall(CopyAssignmentOperator ca | ca = this.getAMemberFunction() |
       ca.isCompilerGenerated() and not ca.isDeleted()
+    ) and
+    (
+      not this instanceof ClassTemplateInstantiation
+      or
+      this.(ClassTemplateInstantiation).getTemplate().hasImplicitCopyAssignmentOperator()
+    ) and
+    (
+      not this instanceof PartialClassTemplateSpecialization
+      or
+      this.(PartialClassTemplateSpecialization)
+          .getPrimaryTemplate()
+          .hasImplicitCopyAssignmentOperator()
     )
   }
 

cpp/ql/test/library-tests/special_members/generated_copy/assign.expected

@@ -11,6 +11,7 @@
 | difference::Base | can | does NOT | have implicit copy assignment |
 | difference::OnlyAssign | can | does | have implicit copy assignment |
 | difference::OnlyCtor | can NOT | does NOT | have implicit copy assignment |
+| instantiated_explicit_ctor::Wrapper<int> | can | does | have implicit copy assignment |
 | moves::MoveAssign | can NOT | does NOT | have implicit copy assignment |
 | moves::MoveCtor | can NOT | does NOT | have implicit copy assignment |
 | private_cc::C | can | does NOT | have implicit copy assignment |

cpp/ql/test/library-tests/special_members/generated_copy/copy.cpp

@@ -131,3 +131,21 @@ namespace difference {
   class OnlyAssign : Base {
   };
 }
+
+namespace instantiated_explicit_ctor {
+  template<class T>
+  class Wrapper {
+  public:
+    Wrapper(Wrapper<T> &other) {
+      m_t = other.m_t;
+    }
+
+    Wrapper() {
+      m_t = 0;
+    }
+  private:
+    T m_t;
+  };
+
+  Wrapper<int> wrapped_int;
+}

cpp/ql/test/library-tests/special_members/generated_copy/ctor.expected

@@ -11,6 +11,7 @@
 | difference::Base | can | does NOT | have implicit copy constructor |
 | difference::OnlyAssign | can NOT | does NOT | have implicit copy constructor |
 | difference::OnlyCtor | can | does | have implicit copy constructor |
+| instantiated_explicit_ctor::Wrapper<int> | can | does NOT | have implicit copy constructor |
 | moves::MoveAssign | can NOT | does NOT | have implicit copy constructor |
 | moves::MoveCtor | can NOT | does NOT | have implicit copy constructor |
 | private_cc::C | can | does NOT | have implicit copy constructor |

cpp/ql/test/library-tests/special_members/generated_copy/functions.expected

@@ -86,5 +86,9 @@
 | copy.cpp:131:9:131:9 | OnlyAssign | deleted |  |
 | copy.cpp:131:9:131:9 | operator= |  |  |
 | copy.cpp:131:9:131:9 | operator= |  |  |
+| copy.cpp:137:9:137:9 | operator= |  |  |
+| copy.cpp:139:5:139:11 | Wrapper |  |  |
+| copy.cpp:143:5:143:5 | Wrapper |  |  |
+| copy.cpp:143:5:143:11 | Wrapper |  |  |
 | file://:0:0:0:0 | operator= |  |  |
 | file://:0:0:0:0 | operator= |  |  |