Merge pull request #1702 from mgrettondann/cpp-add-thread_local-support-external

C++: add thread_local support

cpp/ql/src/Likely Bugs/Memory Management/ReturnStackAllocatedMemory.ql

@@ -45,6 +45,7 @@ predicate hasNontrivialConversion(Expr e) {
 from LocalScopeVariable var, VariableAccess va, ReturnStmt r
 where
   not var.isStatic() and
+  not var.isThreadLocal() and
   not var.getUnspecifiedType() instanceof ReferenceType and
   not r.isFromUninstantiatedTemplate(_) and
   va = var.getAnAccess() and

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

@@ -139,6 +139,13 @@ class Variable extends Declaration, @variable {
     this.hasSpecifier("is_constexpr")
   }
 
+  /**
+   * Holds if this variable is `thread_local`.
+   */
+  predicate isThreadLocal() {
+    this.hasSpecifier("is_thread_local")
+  }
+
   /**
    * Holds if this variable is constructed from `v` as a result
    * of template instantiation. If so, it originates either from a template

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

@@ -88,6 +88,7 @@
 | file://:0:0:0:0 | inline |
 | file://:0:0:0:0 | int |
 | file://:0:0:0:0 | is_constexpr |
+| file://:0:0:0:0 | is_thread_local |
 | file://:0:0:0:0 | long |
 | file://:0:0:0:0 | long double |
 | file://:0:0:0:0 | long long |

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

@@ -65,6 +65,7 @@
 | file://:0:0:0:0 | inline |
 | file://:0:0:0:0 | int |
 | file://:0:0:0:0 | is_constexpr |
+| file://:0:0:0:0 | is_thread_local |
 | file://:0:0:0:0 | long |
 | file://:0:0:0:0 | long double |
 | file://:0:0:0:0 | long long |

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

@@ -113,6 +113,7 @@
 | file://:0:0:0:0 | int & |
 | file://:0:0:0:0 | int * |
 | file://:0:0:0:0 | is_constexpr |
+| file://:0:0:0:0 | is_thread_local |
 | file://:0:0:0:0 | long |
 | file://:0:0:0:0 | long double |
 | file://:0:0:0:0 | long long |

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

@@ -58,6 +58,7 @@
 | file://:0:0:0:0 | int * | Other |
 | file://:0:0:0:0 | int[0] | Other |
 | file://:0:0:0:0 | is_constexpr | Other |
+| file://:0:0:0:0 | is_thread_local | Other |
 | file://:0:0:0:0 | long | Other |
 | file://:0:0:0:0 | long double | Other |
 | file://:0:0:0:0 | long long | Other |

cpp/ql/test/library-tests/variables/thread_local/thread_local.cpp

@@ -0,0 +1,7 @@
+
+void returnThreadLocal() {
+  thread_local int threadLocal;
+  int not_threadLocal;
+  static thread_local int threadLocalStatic;
+  extern thread_local int threadLocalExtern;
+}

cpp/ql/test/library-tests/variables/thread_local/thread_local.expected

@@ -0,0 +1,10 @@
+| file://:0:0:0:0 | fp_offset | false |
+| file://:0:0:0:0 | gp_offset | false |
+| file://:0:0:0:0 | overflow_arg_area | false |
+| file://:0:0:0:0 | p#0 | false |
+| file://:0:0:0:0 | p#0 | false |
+| file://:0:0:0:0 | reg_save_area | false |
+| thread_local.cpp:3:20:3:30 | threadLocal | true |
+| thread_local.cpp:4:7:4:21 | not_threadLocal | false |
+| thread_local.cpp:5:27:5:43 | threadLocalStatic | true |
+| thread_local.cpp:6:27:6:43 | threadLocalExtern | true |

cpp/ql/test/library-tests/variables/thread_local/thread_local.ql

@@ -0,0 +1,6 @@
+import cpp
+
+from Variable v
+select v,
+       any(boolean b | if v.isThreadLocal() then b = true else b = false)
+

cpp/ql/test/query-tests/Likely Bugs/Memory Management/ReturnStackAllocatedMemory/ReturnStackAllocatedMemory.expected

@@ -5,5 +5,4 @@
 | test.cpp:92:2:92:12 | return ... | May return stack-allocated memory from $@. | test.cpp:89:10:89:11 | mc | mc |
 | test.cpp:112:2:112:12 | return ... | May return stack-allocated memory from $@. | test.cpp:112:9:112:11 | arr | arr |
 | test.cpp:119:2:119:19 | return ... | May return stack-allocated memory from $@. | test.cpp:119:11:119:13 | arr | arr |
-| test.cpp:149:3:149:22 | return ... | May return stack-allocated memory from $@. | test.cpp:149:11:149:21 | threadLocal | threadLocal |
 | test.cpp:171:3:171:24 | return ... | May return stack-allocated memory from $@. | test.cpp:170:35:170:41 | myLocal | myLocal |

cpp/ql/test/query-tests/Likely Bugs/Memory Management/ReturnStackAllocatedMemory/test.cpp

@@ -146,7 +146,7 @@ char *testArray5()
 
 int *returnThreadLocal() {
   thread_local int threadLocal;
-  return &threadLocal; // GOOD [FALSE POSITIVE]
+  return &threadLocal; // GOOD
 }
 
 int returnDereferenced() {