C++: Fix toString() predicates that don't hold

cpp/ql/src/semmle/code/cpp/NameQualifiers.qll

@@ -157,4 +157,6 @@ library class SpecialNameQualifyingElement extends NameQualifyingElement,
   @specialnamequalifyingelement {
   /** Gets the name of this special qualifying element. */
   override string getName() { specialnamequalifyingelements(underlyingElement(this), result) }
+
+  override string toString() { result = getName() }
 }

cpp/ql/src/semmle/code/cpp/Preprocessor.qll

@@ -214,7 +214,11 @@ class PreprocessorUndef extends PreprocessorDirective, @ppd_undef {
  * A C/C++ preprocessor `#pragma` directive.
  */
 class PreprocessorPragma extends PreprocessorDirective, @ppd_pragma {
-  override string toString() { result = "#pragma " + this.getHead() }
+  override string toString() {
+    if exists(this.getHead())
+    then result = "#pragma " + this.getHead()
+    else result = "#pragma"
+  }
 }
 
 /**

cpp/ql/test/library-tests/CPP-205/elements.expected

@@ -26,6 +26,7 @@
 | CPP-205.cpp:8:3:8:15 | return ... |  |
 | CPP-205.cpp:8:10:8:11 | call to fn |  |
 | CPP-205.cpp:8:13:8:13 | 0 |  |
+| file://:0:0:0:0 | __super |  |
 | file://:0:0:0:0 | __va_list_tag |  |
 | file://:0:0:0:0 | operator= | function __va_list_tag::operator=(__va_list_tag &&) -> __va_list_tag & |
 | file://:0:0:0:0 | operator= | function __va_list_tag::operator=(const __va_list_tag &) -> __va_list_tag & |

cpp/ql/test/library-tests/clang_ms/element.expected

@@ -23,6 +23,8 @@
 | clang_ms.cpp:11:5:11:13 | asm statement |
 | clang_ms.cpp:12:1:12:1 | return ... |
 | clang_ms.cpp:16:1:16:19 | // Test for CPP-184 |
+| clang_ms.cpp:17:1:17:32 | #pragma |
+| clang_ms.cpp:18:1:18:31 | #pragma |
 | file://:0:0:0:0 |  |
 | file://:0:0:0:0 | (global namespace) |
 | file://:0:0:0:0 | _Complex __float128 |
@@ -48,6 +50,7 @@
 | file://:0:0:0:0 | __ptr32 |
 | file://:0:0:0:0 | __ptr64 |
 | file://:0:0:0:0 | __sptr |
+| file://:0:0:0:0 | __super |
 | file://:0:0:0:0 | __uptr |
 | file://:0:0:0:0 | __va_list_tag |
 | file://:0:0:0:0 | __va_list_tag & |

cpp/ql/test/library-tests/conditions/elements.expected

@@ -27,6 +27,7 @@
 | file://:0:0:0:0 | __ptr32 |
 | file://:0:0:0:0 | __ptr64 |
 | file://:0:0:0:0 | __sptr |
+| file://:0:0:0:0 | __super |
 | file://:0:0:0:0 | __uptr |
 | file://:0:0:0:0 | __va_list_tag |
 | file://:0:0:0:0 | __va_list_tag & |

cpp/ql/test/library-tests/lambdas/captures/elements.expected

@@ -201,6 +201,7 @@
 | file://:0:0:0:0 | ..(*)(..) |
 | file://:0:0:0:0 | ..(*)(..) |
 | file://:0:0:0:0 | ..(..) |
+| file://:0:0:0:0 | __super |
 | file://:0:0:0:0 | __va_list_tag |
 | file://:0:0:0:0 | __va_list_tag & |
 | file://:0:0:0:0 | __va_list_tag && |

cpp/ql/test/library-tests/macros/inmacroexpansion/inmacroexpansion.expected

@@ -1,3 +1,4 @@
+| file://:0:0:0:0 | __super | false |
 | file://:0:0:0:0 | __va_list_tag | false |
 | file://:0:0:0:0 | operator= | false |
 | file://:0:0:0:0 | operator= | false |

cpp/ql/test/library-tests/ptr_to_member/segfault/exprs.ql

@@ -1,4 +1,5 @@
 import cpp
 
 from Expr e
+where exists(e.toString())
 select e, e.getType()

cpp/ql/test/library-tests/templates/CPP-204/element.expected

@@ -7,6 +7,7 @@
 | file://:0:0:0:0 | X |
 | file://:0:0:0:0 | X |
 | file://:0:0:0:0 | Y |
+| file://:0:0:0:0 | __super |
 | file://:0:0:0:0 | __va_list_tag |
 | file://:0:0:0:0 | __va_list_tag & |
 | file://:0:0:0:0 | __va_list_tag && |

cpp/ql/test/library-tests/templates/instantiations_functions/elements.expected

@@ -32,6 +32,7 @@
 | file://:0:0:0:0 | __ptr32 |
 | file://:0:0:0:0 | __ptr64 |
 | file://:0:0:0:0 | __sptr |
+| file://:0:0:0:0 | __super |
 | file://:0:0:0:0 | __uptr |
 | file://:0:0:0:0 | __va_list_tag |
 | file://:0:0:0:0 | __va_list_tag & |

cpp/ql/test/library-tests/unnamed/elements.expected

@@ -24,6 +24,7 @@
 | file://:0:0:0:0 | __ptr32 | Other |
 | file://:0:0:0:0 | __ptr64 | Other |
 | file://:0:0:0:0 | __sptr | Other |
+| file://:0:0:0:0 | __super | Other |
 | file://:0:0:0:0 | __uptr | Other |
 | file://:0:0:0:0 | __va_list_tag | Other |
 | file://:0:0:0:0 | abstract | Other |

cpp/ql/test/library-tests/unnamed/elements.ql

@@ -3,5 +3,6 @@ import cpp
 from Element e, string s
 where
   not e instanceof Folder and
+  exists(e.toString()) and // Work around `VariableDeclarationEntry.toString()` not holding
   if e instanceof VariableAccess then s = "Variable access" else s = "Other"
 select e, s