Merge pull request #1860 from matt-gretton-dann/add-using-aliases

Add support for using aliases

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

@@ -3,11 +3,17 @@ private import semmle.code.cpp.internal.ResolveClass
 
 /**
  * A C/C++ typedef type. See 4.9.1.
+ *
+ * Represents either of the following typedef styles:
+ *
+ *   * CTypedefType: typedef <type> <name>;
+ *   * UsingAliasTypedefType: using <name> = <type>;
  */
 class TypedefType extends UserType {
-  TypedefType() { usertypes(underlyingElement(this), _, 5) }
-
-  override string getCanonicalQLClass() { result = "TypedefType" }
+  TypedefType() {
+    usertypes(underlyingElement(this), _, 5) or
+    usertypes(underlyingElement(this), _, 14)
+  }
 
   /**
    * Gets the base type of this typedef type.
@@ -26,10 +32,6 @@ class TypedefType extends UserType {
     result = this.getBaseType().getPointerIndirectionLevel()
   }
 
-  override string explain() {
-    result = "typedef {" + this.getBaseType().explain() + "} as \"" + this.getName() + "\""
-  }
-
   override predicate isDeeplyConst() { this.getBaseType().isDeeplyConst() } // Just an alias
 
   override predicate isDeeplyConstBelow() { this.getBaseType().isDeeplyConstBelow() } // Just an alias
@@ -45,6 +47,32 @@ class TypedefType extends UserType {
   override Type stripType() { result = getBaseType().stripType() }
 }
 
+/**
+ * A traditional C/C++ typedef type. See 4.9.1.
+ */
+class CTypedefType extends TypedefType {
+  CTypedefType() { usertypes(underlyingElement(this), _, 5) }
+
+  override string getCanonicalQLClass() { result = "CTypedefType" }
+
+  override string explain() {
+    result = "typedef {" + this.getBaseType().explain() + "} as \"" + this.getName() + "\""
+  }
+}
+
+/**
+ * A using alias C++ typedef type.
+ */
+class UsingAliasTypedefType extends TypedefType {
+  UsingAliasTypedefType() { usertypes(underlyingElement(this), _, 14) }
+
+  override string getCanonicalQLClass() { result = "UsingAliasTypedefType" }
+
+  override string explain() {
+    result = "using {" + this.getBaseType().explain() + "} as \"" + this.getName() + "\""
+  }
+}
+
 /**
  * A C++ typedef type that is directly enclosed by a function.
  */

cpp/ql/src/semmlecode.cpp.dbscheme

@@ -675,7 +675,7 @@ decltypes(
   | 2 = class
   | 3 = union
   | 4 = enum
-  | 5 = typedef
+  | 5 = typedef                       // classic C: typedef typedef type name
   | 6 = template
   | 7 = template_parameter
   | 8 = template_template_parameter
@@ -684,6 +684,7 @@ decltypes(
 // ... 11 objc_protocol deprecated
 // ... 12 objc_category deprecated
   | 13 = scoped_enum
+  | 14 = using_alias                  // a using name = type style typedef
   ;
 */
 usertypes(

cpp/ql/test/examples/expressions/PrintAST.expected

@@ -917,7 +917,7 @@ Varargs.c:
 #    8|   body: [Block] { ... }
 #    9|     0: [DeclStmt] declaration
 #    9|       0: [VariableDeclarationEntry] definition of args
-#    9|           Type = [TypedefType] va_list
+#    9|           Type = [CTypedefType] va_list
 #   10|     1: [ExprStmt] ExprStmt
 #   10|       0: [BuiltInVarArgsStart] __builtin_va_start
 #   10|           Type = [VoidType] void
@@ -926,7 +926,7 @@ Varargs.c:
 #   10|             Type = [PointerType] __va_list_tag *
 #   10|             ValueCategory = prvalue
 #   10|           expr: [VariableAccess] args
-#   10|               Type = [TypedefType] va_list
+#   10|               Type = [CTypedefType] va_list
 #   10|               ValueCategory = lvalue
 #   10|         1: [VariableAccess] text
 #   10|             Type = [PointerType] const char *
@@ -939,7 +939,7 @@ Varargs.c:
 #   11|             Type = [PointerType] __va_list_tag *
 #   11|             ValueCategory = prvalue
 #   11|           expr: [VariableAccess] args
-#   11|               Type = [TypedefType] va_list
+#   11|               Type = [CTypedefType] va_list
 #   11|               ValueCategory = lvalue
 #   12|     3: [ReturnStmt] return ...
 macro_etc.c:

cpp/ql/test/library-tests/ir/ir/PrintAST.expected

@@ -3672,7 +3672,7 @@ ir.cpp:
 #  560| [TopLevelFunction] int EnumSwitch(E)
 #  560|   params: 
 #  560|     0: [Parameter] e
-#  560|         Type = [TypedefType] E
+#  560|         Type = [CTypedefType] E
 #  560|   body: [Block] { ... }
 #  561|     0: [SwitchStmt] switch (...) ... 
 #  561|       0: [CStyleCast] (int)...
@@ -3680,7 +3680,7 @@ ir.cpp:
 #  561|           Type = [IntType] int
 #  561|           ValueCategory = prvalue
 #  561|         expr: [VariableAccess] e
-#  561|             Type = [TypedefType] E
+#  561|             Type = [CTypedefType] E
 #  561|             ValueCategory = prvalue(load)
 #  561|       1: [Block] { ... }
 #  562|         0: [SwitchCase] case ...:
@@ -6191,19 +6191,19 @@ ir.cpp:
 #  915| [Operator,TopLevelFunction] void* operator new(size_t, float)
 #  915|   params: 
 #  915|     0: [Parameter] p#0
-#  915|         Type = [Size_t,TypedefType] size_t
+#  915|         Type = [CTypedefType,Size_t] size_t
 #  915|     1: [Parameter] p#1
 #  915|         Type = [FloatType] float
 #  916| [Operator,TopLevelFunction] void* operator new[](size_t, float)
 #  916|   params: 
 #  916|     0: [Parameter] p#0
-#  916|         Type = [Size_t,TypedefType] size_t
+#  916|         Type = [CTypedefType,Size_t] size_t
 #  916|     1: [Parameter] p#1
 #  916|         Type = [FloatType] float
 #  917| [Operator,TopLevelFunction] void* operator new(size_t, std::align_val_t, float)
 #  917|   params: 
 #  917|     0: [Parameter] p#0
-#  917|         Type = [Size_t,TypedefType] size_t
+#  917|         Type = [CTypedefType,Size_t] size_t
 #  917|     1: [Parameter] p#1
 #  917|         Type = [ScopedEnum] align_val_t
 #  917|     2: [Parameter] p#2
@@ -6211,7 +6211,7 @@ ir.cpp:
 #  918| [Operator,TopLevelFunction] void* operator new[](size_t, std::align_val_t, float)
 #  918|   params: 
 #  918|     0: [Parameter] p#0
-#  918|         Type = [Size_t,TypedefType] size_t
+#  918|         Type = [CTypedefType,Size_t] size_t
 #  918|     1: [Parameter] p#1
 #  918|         Type = [ScopedEnum] align_val_t
 #  918|     2: [Parameter] p#2
@@ -6255,23 +6255,23 @@ ir.cpp:
 #  926| [MemberFunction] void* SizedDealloc::operator new(size_t)
 #  926|   params: 
 #  926|     0: [Parameter] p#0
-#  926|         Type = [Size_t,TypedefType] size_t
+#  926|         Type = [CTypedefType,Size_t] size_t
 #  927| [MemberFunction] void* SizedDealloc::operator new[](size_t)
 #  927|   params: 
 #  927|     0: [Parameter] p#0
-#  927|         Type = [Size_t,TypedefType] size_t
+#  927|         Type = [CTypedefType,Size_t] size_t
 #  928| [MemberFunction] void SizedDealloc::operator delete(void*, size_t)
 #  928|   params: 
 #  928|     0: [Parameter] p#0
 #  928|         Type = [VoidPointerType] void *
 #  928|     1: [Parameter] p#1
-#  928|         Type = [Size_t,TypedefType] size_t
+#  928|         Type = [CTypedefType,Size_t] size_t
 #  929| [MemberFunction] void SizedDealloc::operator delete[](void*, size_t)
 #  929|   params: 
 #  929|     0: [Parameter] p#0
 #  929|         Type = [VoidPointerType] void *
 #  929|     1: [Parameter] p#1
-#  929|         Type = [Size_t,TypedefType] size_t
+#  929|         Type = [CTypedefType,Size_t] size_t
 #  932| [CopyAssignmentOperator] Overaligned& Overaligned::operator=(Overaligned const&)
 #  932|   params: 
 #-----|     0: [Parameter] p#0
@@ -7855,7 +7855,7 @@ ir.cpp:
 # 1118|           Type = [IntType] int
 # 1119|     4: [DeclStmt] declaration
 # 1119|       0: [TypeDeclarationEntry] declaration of d
-# 1119|           Type = [LocalTypedefType] d
+# 1119|           Type = [CTypedefType,LocalTypedefType] d
 # 1120|     5: [ReturnStmt] return ...
 # 1117| [TopLevelFunction] int f(float)
 # 1117|   params: 

cpp/ql/test/library-tests/typedefs/Typedefs2.expected

@@ -1,2 +1,2 @@
-| typedefs.cpp:6:6:6:7 | f1 | typedefs.cpp:8:15:8:18 | TYPE | LocalTypedefType |
+| typedefs.cpp:6:6:6:7 | f1 | typedefs.cpp:8:15:8:18 | TYPE | CTypedefType, LocalTypedefType |
 | typedefs.cpp:6:6:6:7 | f1 | typedefs.cpp:9:9:9:9 | D | DirectAccessHolder, LocalClass, MetricClass, StructLikeClass |

cpp/ql/test/library-tests/types/wchar_t_typedef/wchar_t.expected

@@ -1,3 +1,3 @@
 | file://:0:0:0:0 | wchar_t | Wchar_t, WideCharType |  |
-| file://:0:0:0:0 | wchar_t * | PointerType | TypedefType, Wchar_t |
-| ms.c:2:24:2:30 | wchar_t | TypedefType, Wchar_t |  |
+| file://:0:0:0:0 | wchar_t * | PointerType | CTypedefType, Wchar_t |
+| ms.c:2:24:2:30 | wchar_t | CTypedefType, Wchar_t |  |

cpp/ql/test/library-tests/using-aliases/using-alias.cpp

@@ -0,0 +1,10 @@
+
+typedef int type1;
+using using1 = float;
+
+typedef using1 type2;
+using using2 = type1;
+
+template<typename T> struct S { using X = T*; };
+
+using Y = S<int>::X;

cpp/ql/test/library-tests/using-aliases/using-alias.expected

@@ -0,0 +1,9 @@
+| file://:0:0:0:0 | X | NestedTypedefType | file://:0:0:0:0 | int * |
+| file://:0:0:0:0 | X | UsingAliasTypedefType | file://:0:0:0:0 | int * |
+| using-alias.cpp:2:13:2:17 | type1 | CTypedefType | file://:0:0:0:0 | int |
+| using-alias.cpp:3:7:3:12 | using1 | UsingAliasTypedefType | file://:0:0:0:0 | float |
+| using-alias.cpp:5:16:5:20 | type2 | CTypedefType | file://:0:0:0:0 | float |
+| using-alias.cpp:6:7:6:12 | using2 | UsingAliasTypedefType | file://:0:0:0:0 | int |
+| using-alias.cpp:8:39:8:39 | X | NestedTypedefType | file://:0:0:0:0 | T * |
+| using-alias.cpp:8:39:8:39 | X | UsingAliasTypedefType | file://:0:0:0:0 | T * |
+| using-alias.cpp:10:7:10:7 | Y | UsingAliasTypedefType | file://:0:0:0:0 | int * |

cpp/ql/test/library-tests/using-aliases/using-alias.ql

@@ -0,0 +1,4 @@
+import cpp
+
+from TypedefType t
+select t, t.getCanonicalQLClass(), t.getUnderlyingType()