Implement C package DeadCode

c/common/test/rules/deadcode/DeadCode.expected

@@ -0,0 +1,11 @@
+| test.c:18:3:18:27 | declaration | This statement is dead code. |
+| test.c:19:3:19:12 | ExprStmt | This statement is dead code. |
+| test.c:20:3:20:12 | ExprStmt | This statement is dead code. |
+| test.c:22:3:24:3 | if (...) ...  | This statement is dead code. |
+| test.c:34:3:35:3 | if (...) ...  | This statement is dead code. |
+| test.c:37:3:37:4 | { ... } | This statement is dead code. |
+| test.c:38:3:40:3 | { ... } | This statement is dead code. |
+| test.c:54:6:55:3 | { ... } | This statement is dead code. |
+| test.c:65:46:66:3 | { ... } | This statement is dead code. |
+| test.c:69:3:69:8 | ExprStmt | This statement is dead code. |
+| test.c:71:3:71:21 | ExprStmt | This statement is dead code. |

c/common/test/rules/deadcode/DeadCode.ql

@@ -0,0 +1,2 @@
+// GENERATED FILE - DO NOT MODIFY
+import codingstandards.cpp.rules.deadcode.DeadCode

c/common/test/rules/deadcode/test.c

@@ -0,0 +1,74 @@
+// NOTICE: THE TEST CASES BELOW ARE ALSO INCLUDED IN THE C++ TEST CASE AND
+// CHANGES SHOULD BE REFLECTED THERE AS WELL.
+#include <stdbool.h>
+
+int may_have_side_effects();
+int no_side_effects(int x) { return 1 + 2; }
+int no_side_effects_nondeterministic();
+
+int test_dead_code(int x) {
+  int live1 = may_have_side_effects(),
+      live2 = may_have_side_effects(); // COMPLIANT
+  int live3 = 0,
+      live4 = may_have_side_effects(); // COMPLIANT
+  int live5 = 0, live6 = 0;            // COMPLIANT
+  live5 = 1;                           // COMPLIANT
+  live6 = 2;                           // COMPLIANT
+
+  int dead1 = 0, dead2 = 0; // NON_COMPLIANT
+  dead1 = 1;                // NON_COMPLIANT - useless assignment
+  dead2 = 1;                // NON_COMPLIANT - useless assignment
+
+  if (false) {  // NON_COMPLIANT
+    dead2 = 10; // Only used in dead or unreachable code
+  }
+
+  if (true) { // COMPLIANT
+    may_have_side_effects();
+  }
+
+  if (may_have_side_effects()) { // COMPLIANT
+    may_have_side_effects();
+  }
+
+  if (true) { // NON_COMPLIANT
+  }
+
+  {} // NON_COMPLIANT
+  {  // NON_COMPLIANT
+    1 + 2;
+  }
+
+  { // COMPLIANT
+    may_have_side_effects();
+  }
+
+  do { // COMPLIANT
+    may_have_side_effects();
+  } while (may_have_side_effects());
+
+  do { // COMPLIANT
+    may_have_side_effects();
+  } while (may_have_side_effects());
+
+  do { // NON_COMPLIANT
+  } while (no_side_effects_nondeterministic());
+
+  while (may_have_side_effects()) { // COMPLIANT
+    may_have_side_effects();
+  }
+
+  while (may_have_side_effects()) { // COMPLIANT
+    may_have_side_effects();
+  }
+
+  while (no_side_effects_nondeterministic()) { // NON_COMPLIANT
+  }
+
+  may_have_side_effects(); // COMPLIANT
+  1 + 2;                   // NON_COMPLIANT
+
+  no_side_effects(x); // NON_COMPLIANT
+
+  return live5 + live6; // COMPLIANT
+}

c/common/test/rules/unreachablecode/UnreachableCode.expected

@@ -0,0 +1,2 @@
+| test.c:17:3:17:12 | declaration | This statement in function $@ is unreachable. | test.c:15:5:15:21 | test_after_return | test_after_return |
+| test.c:21:10:22:12 | { ... } | This statement in function $@ is unreachable. | test.c:20:5:20:27 | test_constant_condition | test_constant_condition |

c/common/test/rules/unreachablecode/UnreachableCode.ql

@@ -0,0 +1,2 @@
+// GENERATED FILE - DO NOT MODIFY
+import codingstandards.cpp.rules.unreachablecode.UnreachableCode

c/common/test/rules/unreachablecode/test.c

@@ -0,0 +1,26 @@
+// NOTICE: THE TEST CASES BELOW ARE ALSO INCLUDED IN THE C++ TEST CASE AND
+// CHANGES SHOULD BE REFLECTED THERE AS WELL.
+
+void test_switch(int p1) {
+  int l1 = 0;
+  switch (p1) {
+    l1 = p1; // NON_COMPLIANT[FALSE_NEGATIVE]
+  case 1:
+    break;
+  default:
+    break;
+  }
+}
+
+int test_after_return() {
+  return 0;
+  int l1 = 0; // NON_COMPLIANT - function has returned by this point
+}
+
+int test_constant_condition() {
+  if (0) { // NON_COMPLIANT
+    return 1;
+  } else { // COMPLIANT
+    return 2;
+  }
+}

c/common/test/rules/unusedparameter/UnusedParameter.expected

@@ -0,0 +1 @@
+| test.c:6:22:6:22 | x | Unused parameter 'x' for function $@. | test.c:6:6:6:16 | test_unused | test_unused |

c/common/test/rules/unusedparameter/UnusedParameter.ql

@@ -0,0 +1,2 @@
+// GENERATED FILE - DO NOT MODIFY
+import codingstandards.cpp.rules.unusedparameter.UnusedParameter

c/common/test/rules/unusedparameter/test.c

@@ -0,0 +1,8 @@
+// NOTICE: THE TEST CASES BELOW ARE ALSO INCLUDED IN THE C++ TEST CASE AND
+// CHANGES SHOULD BE REFLECTED THERE AS WELL.
+
+int test_used(int x) { return x; } // COMPLIANT
+
+void test_unused(int x) {} // NON_COMPLIANT
+
+void test_no_def(int x); // COMPLIANT - no definition, so cannot be "unused"

c/common/test/rules/unusedtypedeclarations/UnusedTypeDeclarations.expected

@@ -0,0 +1,5 @@
+| file://:0:0:0:0 | __va_list_tag | Type declaration __va_list_tag is not used. |
+| test.c:4:8:4:8 | A | Type declaration A is not used. |
+| test.c:7:18:7:18 | D | Type declaration D is not used. |
+| test.c:28:11:28:11 | R | Type declaration R is not used. |
+| test.c:41:12:41:12 | struct <unnamed> | Type declaration struct <unnamed> is not used. |

c/common/test/rules/unusedtypedeclarations/UnusedTypeDeclarations.ql

@@ -0,0 +1,2 @@
+// GENERATED FILE - DO NOT MODIFY
+import codingstandards.cpp.rules.unusedtypedeclarations.UnusedTypeDeclarations

c/common/test/rules/unusedtypedeclarations/test.c

@@ -0,0 +1,52 @@
+// NOTICE: THE TEST CASES BELOW ARE ALSO INCLUDED IN THE C++ TEST CASE AND
+// CHANGES SHOULD BE REFLECTED THERE AS WELL.
+
+struct A {}; // NON_COMPLIANT - unused
+
+struct C {};        // COMPLIANT - used in the type def
+typedef struct C D; // NON_COMPLIANT - typedef itself not used
+
+struct F {}; // COMPLIANT - used as a global function return type
+
+struct F test_return_value() {
+  struct F f;
+  return f;
+}
+
+struct G {}; // COMPLIANT - used as a global function parameter type
+
+void test_global_function(struct G g) {}
+
+enum M { C1, C2, C3 }; // COMPLIANT - used in an enum type access below
+
+void test_enum_access() { int i = C1; }
+
+struct O {}; // COMPLIANT - used in typedef below
+
+typedef struct O P; // COMPLIANT - used in typedef below
+typedef P Q;        // COMPLIANT - used in function below
+typedef Q R;        // NON_COMPLIANT - never used
+
+Q test_type_def() {}
+
+struct {     // COMPLIANT - used in type definition
+  union {    // COMPLIANT - f1 and f3 is accessed
+    struct { // COMPLIANT - f1 is accessed
+      int f1;
+    };
+    struct { // COMPLIANT - f3 is accessed
+      float f2;
+      float f3;
+    };
+    struct { // NON_COMPLIANT - f4 is never accessed
+      long f4;
+    };
+  };
+  int f5;
+} s;
+
+void test_nested_struct() {
+  s.f1;
+  s.f3;
+  s.f5;
+}

c/misra/src/rules/RULE-2-1/UnreachableCode.ql

@@ -0,0 +1,23 @@
+/**
+ * @id c/misra/unreachable-code
+ * @name RULE-2-1: A project shall not contain unreachable code
+ * @description Unreachable code complicates the program and can indicate a possible mistake on the
+ *              part of the programmer.
+ * @kind problem
+ * @precision very-high
+ * @problem.severity warning
+ * @tags external/misra/id/rule-2-1
+ *       readability
+ *       maintainability
+ *       external/misra/obligation/required
+ */
+
+import cpp
+import codingstandards.c.misra
+import codingstandards.cpp.rules.unreachablecode.UnreachableCode
+
+class UnreachableCodeQuery extends UnreachableCodeSharedQuery {
+  UnreachableCodeQuery() {
+    this = DeadCodePackage::unreachableCodeQuery()
+  }
+}

c/misra/src/rules/RULE-2-2/DeadCode.ql

@@ -0,0 +1,21 @@
+/**
+ * @id c/misra/dead-code
+ * @name RULE-2-2: There shall be no dead code
+ * @description Dead code complicates the program and can indicate a possible mistake on the part of
+ *              the programmer.
+ * @kind problem
+ * @precision very-high
+ * @problem.severity warning
+ * @tags external/misra/id/rule-2-2
+ *       readability
+ *       maintainability
+ *       external/misra/obligation/required
+ */
+
+import cpp
+import codingstandards.c.misra
+import codingstandards.cpp.rules.deadcode.DeadCode
+
+class MisraCDeadCodeQuery extends DeadCodeSharedQuery {
+  MisraCDeadCodeQuery() { this = DeadCodePackage::deadCodeQuery() }
+}

c/misra/src/rules/RULE-2-3/UnusedTypeDeclarations.ql

@@ -0,0 +1,21 @@
+/**
+ * @id c/misra/unused-type-declarations
+ * @name RULE-2-3: A project should not contain unused type declarations
+ * @description Unused type declarations are either redundant or indicate a possible mistake on the
+ *              part of the programmer.
+ * @kind problem
+ * @precision very-high
+ * @problem.severity warning
+ * @tags external/misra/id/rule-2-3
+ *       readability
+ *       maintainability
+ *       external/misra/obligation/advisory
+ */
+
+import cpp
+import codingstandards.c.misra
+import codingstandards.cpp.rules.unusedtypedeclarations.UnusedTypeDeclarations
+
+class UnusedTypeDeclarationsQuery extends UnusedTypeDeclarationsSharedQuery {
+  UnusedTypeDeclarationsQuery() { this = DeadCodePackage::unusedTypeDeclarationsQuery() }
+}

c/misra/src/rules/RULE-2-4/UnusedTagDeclaration.ql

@@ -0,0 +1,33 @@
+/**
+ * @id c/misra/unused-tag-declaration
+ * @name RULE-2-4: A project should not contain unused tag declarations
+ * @description Unused tag declarations are either redundant or indicate a possible mistake on the
+ *              part of the programmer.
+ * @kind problem
+ * @precision very-high
+ * @problem.severity warning
+ * @tags external/misra/id/rule-2-4
+ *       readability
+ *       maintainability
+ *       external/misra/obligation/advisory
+ */
+
+import cpp
+import codingstandards.c.misra
+import codingstandards.cpp.TypeUses
+
+from UserType s
+where
+  not isExcluded(s, DeadCodePackage::unusedTagDeclarationQuery()) and
+  // ignore structs without a tag name
+  not s.getName() = "struct <unnamed>" and
+  // typedefs do not have a "tag" name, so this rule does not apply to them
+  not s instanceof TypedefType and
+  // Not mentioned anywhere
+  not exists(TypeMention tm | tm.getMentionedType() = s) and
+  // Exclude any struct that is fully generated from a macro expansion, as it may be used in other
+  // expansions of the same macro.
+  // Note: due to a bug in the CodeQL CLI version 2.9.4, this will currently have no effect, because
+  // `isInMacroExpansion` is broken for `UserType`s.
+  not s.isInMacroExpansion()
+select s, "struct " + s.getName() + " has an unused tag."

c/misra/src/rules/RULE-2-5/UnusedMacroDeclaration.ql

@@ -0,0 +1,28 @@
+/**
+ * @id c/misra/unused-macro-declaration
+ * @name RULE-2-5: A project should not contain unused macro declarations
+ * @description Unused macro declarations are either redundant or indicate a possible mistake on the
+ *              part of the programmer.
+ * @kind problem
+ * @precision very-high
+ * @problem.severity warning
+ * @tags external/misra/id/rule-2-5
+ *       readability
+ *       maintainability
+ *       external/misra/obligation/advisory
+ */
+
+import cpp
+import codingstandards.c.misra
+
+from Macro m
+where
+  not isExcluded(m, DeadCodePackage::unusedMacroDeclarationQuery()) and
+  not exists(MacroAccess ma | ma.getMacro() = m) and
+  // We consider a macro "used" if the name is undef-ed at some point in the same file, or a file
+  // that includes the file defining the macro. This will over approximate use in the case of a
+  // macro which is defined, then undefined, then re-defined but not used.
+  not exists(PreprocessorUndef u |
+    u.getName() = m.getName() and u.getFile().getAnIncludedFile*() = m.getFile()
+  )
+select m, "Macro " + m.getName() + " is unused."

c/misra/src/rules/RULE-2-6/UnusedLabelDeclaration.ql

@@ -0,0 +1,25 @@
+/**
+ * @id c/misra/unused-label-declaration
+ * @name RULE-2-6: A function should not contain unused label declarations
+ * @description Unused label declarations are either redundant or indicate a possible mistake on the
+ *              part of the programmer.
+ * @kind problem
+ * @precision very-high
+ * @problem.severity warning
+ * @tags external/misra/id/rule-2-6
+ *       readability
+ *       maintainability
+ *       external/misra/obligation/advisory
+ */
+
+import cpp
+import codingstandards.c.misra
+
+from LabelStmt label
+where
+  not isExcluded(label, DeadCodePackage::unusedLabelDeclarationQuery()) and
+  // No GotoStmt jumps to this label
+  not exists(GotoStmt gs | gs.hasName() and gs.getTarget() = label) and
+  // The address of the label is never taken
+  not exists(LabelLiteral literal | literal.getLabel() = label)
+select label, "Label " + label.getName() + " is unused."

c/misra/src/rules/RULE-2-7/UnusedParameter.ql

@@ -0,0 +1,22 @@
+/**
+ * @id c/misra/unused-parameter
+ * @name RULE-2-7: There should be no unused parameters in functions
+ * @description Unused parameters can indicate a mistake when implementing the function.
+ * @kind problem
+ * @precision very-high
+ * @problem.severity warning
+ * @tags external/misra/id/rule-2-7
+ *       readability
+ *       maintainability
+ *       external/misra/obligation/advisory
+ */
+
+import cpp
+import codingstandards.c.misra
+import codingstandards.cpp.rules.unusedparameter.UnusedParameter
+
+class UnusedParameterQuery extends UnusedParameterSharedQuery {
+  UnusedParameterQuery() {
+    this = DeadCodePackage::unusedParameterQuery()
+  }
+}

c/misra/test/rules/RULE-2-1/UnreachableCode.testref

@@ -0,0 +1 @@
+c/common/test/rules/unreachablecode/UnreachableCode.ql

c/misra/test/rules/RULE-2-2/DeadCode.testref

@@ -0,0 +1 @@
+c/common/test/rules/deadcode/DeadCode.ql

c/misra/test/rules/RULE-2-3/UnusedTypeDeclarations.testref

@@ -0,0 +1 @@
+c/common/test/rules/unusedtypedeclarations/UnusedTypeDeclarations.ql

c/misra/test/rules/RULE-2-4/UnusedTagDeclaration.expected

@@ -0,0 +1,7 @@
+| test.c:4:8:4:9 | S2 | struct S2 has an unused tag. |
+| test.c:7:16:7:17 | S3 | struct S3 has an unused tag. |
+| test.c:17:6:17:7 | E1 | struct E1 has an unused tag. |
+| test.c:31:10:31:11 | S7 | struct S7 has an unused tag. |
+| test.c:50:8:50:10 | S10 | struct S10 has an unused tag. |
+| test.c:66:3:66:14 | S13 | struct S13 has an unused tag. |
+| test.c:79:8:79:10 | s14 | struct s14 has an unused tag. |