C++: Support inline namespaces in hasQualifiedName/3

change-notes/1.21/analysis-cpp.md

@@ -31,7 +31,7 @@
 
 ## Changes to QL libraries
 - The predicate `Declaration.hasGlobalName` now only holds for declarations that are not nested in a class. For example, it no longer holds for a member function `MyClass::myFunction` or a constructor `MyClass::MyClass`, whereas previously it would classify those two declarations as global names.
-- In class `Declaration`, predicates `getQualifiedName/0` and `hasQualifiedName/1` are no longer recommended for finding functions by name. Instead, use `hasGlobalName/1` and the new `hasQualifiedName/2` and `hasQualifiedName/3` predicates. This improves performance and makes it more reliable to identify names involving templates.
+- In class `Declaration`, predicates `getQualifiedName/0` and `hasQualifiedName/1` are no longer recommended for finding functions by name. Instead, use `hasGlobalName/1` and the new `hasQualifiedName/2` and `hasQualifiedName/3` predicates. This improves performance and makes it more reliable to identify names involving templates and inline namespaces.
 - Additional support for definition by reference has been added to the `semmle.code.cpp.dataflow.TaintTracking` library.
     - The taint tracking library now includes taint-specific edges for functions modeled in `semmle.code.cpp.models.interfaces.DataFlow`.
     - The taint tracking library adds flow through library functions that are modeled in `semmle.code.cpp.models.interfaces.Taint`. Queries can add subclasses of `TaintFunction` to specify additional flow.

cpp/ql/src/semmle/code/cpp/internal/QualifiedName.qll

@@ -26,6 +26,32 @@ class Namespace extends @namespace {
     else result = this.getName()
   }
 
+  /**
+   * Gets a namespace qualifier, like `"namespace1::namespace2"`, through which
+   * the members of this namespace can be named. When `inline namespace` is
+   * used, this predicate may have multiple results.
+   *
+   * This predicate does not take namespace aliases into account. Unlike inline
+   * namespaces, specialization of templates cannot happen through an alias.
+   * Aliases are also local to the compilation unit, while inline namespaces
+   * affect the whole program.
+   */
+  string getAQualifierForMembers() {
+    if namespacembrs(_, this)
+    then
+      exists(Namespace ns |
+        namespacembrs(ns, this)
+      |
+        result = ns.getAQualifierForMembers() + "::" + this.getName()
+        or
+        // If this is an inline namespace, its members are also visible in any
+        // namespace where the members of the parent are visible.
+        namespace_inline(this) and
+        result = ns.getAQualifierForMembers()
+      )
+    else result = this.getName()
+  }
+
   Declaration getADeclaration() {
     if this.getName() = ""
     then result.isTopLevel() and not namespacembrs(_, result)
@@ -331,7 +357,7 @@ cached
 private predicate declarationHasQualifiedName(
   string baseName, string typeQualifier, string namespaceQualifier, Declaration d
 ) {
-  namespaceQualifier = d.getNamespace().getQualifiedName() and
+  namespaceQualifier = d.getNamespace().getAQualifierForMembers() and
   (
     if hasTypeQualifier(d)
     then typeQualifier = d.getTypeQualifierWithoutArgs()

cpp/ql/test/library-tests/identifiers/qualified_names/qualifiedNames.cpp

@@ -59,3 +59,26 @@ namespace templates {
     return getMember(tc, typedefC());
   }
 }
+
+namespace std {
+  inline namespace cpp17 {
+    void functionInTwoNamespaces();
+    class classInTwoNameSpaces {
+    };
+    inline namespace implementation {
+      namespace ns {
+        void functionInFourNamespaces();
+      }
+    }
+  }
+}
+
+// This code demonstrates that `functionInFourNamespaces` is indeed visible in
+// four name spaces.
+using void_fptr = void(*)();
+void_fptr ptrs[] = {
+  std::ns::functionInFourNamespaces,
+  std::cpp17::ns::functionInFourNamespaces,
+  std::implementation::ns::functionInFourNamespaces,
+  std::cpp17::implementation::ns::functionInFourNamespaces,
+};

cpp/ql/test/library-tests/identifiers/qualified_names/qualifiedNames.expected

@@ -52,3 +52,17 @@
 | qualifiedNames.cpp:53:12:53:12 | getMember | templates::getMember | templates |  | getMember | (not global) |
 | qualifiedNames.cpp:53:12:53:20 | getMember | templates::getMember | templates |  | getMember | (not global) |
 | qualifiedNames.cpp:57:8:57:10 | use | templates::use | templates |  | use | (not global) |
+| qualifiedNames.cpp:65:10:65:32 | functionInTwoNamespaces | std::cpp17::functionInTwoNamespaces | std |  | functionInTwoNamespaces | (not global) |
+| qualifiedNames.cpp:65:10:65:32 | functionInTwoNamespaces | std::cpp17::functionInTwoNamespaces | std::cpp17 |  | functionInTwoNamespaces | (not global) |
+| qualifiedNames.cpp:66:11:66:11 | operator= | std::cpp17::classInTwoNameSpaces::operator= | std | classInTwoNameSpaces | operator= | (not global) |
+| qualifiedNames.cpp:66:11:66:11 | operator= | std::cpp17::classInTwoNameSpaces::operator= | std | classInTwoNameSpaces | operator= | (not global) |
+| qualifiedNames.cpp:66:11:66:11 | operator= | std::cpp17::classInTwoNameSpaces::operator= | std::cpp17 | classInTwoNameSpaces | operator= | (not global) |
+| qualifiedNames.cpp:66:11:66:11 | operator= | std::cpp17::classInTwoNameSpaces::operator= | std::cpp17 | classInTwoNameSpaces | operator= | (not global) |
+| qualifiedNames.cpp:66:11:66:30 | classInTwoNameSpaces | std::cpp17::classInTwoNameSpaces | std |  | classInTwoNameSpaces | (not global) |
+| qualifiedNames.cpp:66:11:66:30 | classInTwoNameSpaces | std::cpp17::classInTwoNameSpaces | std::cpp17 |  | classInTwoNameSpaces | (not global) |
+| qualifiedNames.cpp:70:14:70:37 | functionInFourNamespaces | std::cpp17::implementation::ns::functionInFourNamespaces | std::cpp17::implementation::ns |  | functionInFourNamespaces | (not global) |
+| qualifiedNames.cpp:70:14:70:37 | functionInFourNamespaces | std::cpp17::implementation::ns::functionInFourNamespaces | std::cpp17::ns |  | functionInFourNamespaces | (not global) |
+| qualifiedNames.cpp:70:14:70:37 | functionInFourNamespaces | std::cpp17::implementation::ns::functionInFourNamespaces | std::implementation::ns |  | functionInFourNamespaces | (not global) |
+| qualifiedNames.cpp:70:14:70:37 | functionInFourNamespaces | std::cpp17::implementation::ns::functionInFourNamespaces | std::ns |  | functionInFourNamespaces | (not global) |
+| qualifiedNames.cpp:78:7:78:15 | void_fptr | void_fptr |  |  | void_fptr | void_fptr |
+| qualifiedNames.cpp:79:11:79:14 | ptrs | ptrs |  |  | ptrs | ptrs |