Declarations1: add rule DCL31-C

Author: knewbury01

c/cert/src/rules/DCL31-C/DeclareIdentifiersBeforeUsingThem.md

@@ -0,0 +1,18 @@
+# DCL31-C: Declare identifiers before using them
+
+This query implements the CERT-C rule DCL31-C:
+
+> Declare identifiers before using them
+
+
+## CERT
+
+** REPLACE THIS BY RUNNING THE SCRIPT `scripts/help/cert-help-extraction.py` **
+
+## Implementation notes
+
+This query does not check for implicit function declarations as this is partially compiler checked.
+
+## References
+
+* CERT-C: [DCL31-C: Declare identifiers before using them](https://wiki.sei.cmu.edu/confluence/display/c)

c/cert/src/rules/DCL31-C/DeclareIdentifiersBeforeUsingThem.ql

@@ -0,0 +1,21 @@
+/**
+ * @id c/cert/declare-identifiers-before-using-them
+ * @name DCL31-C: Declare identifiers before using them
+ * @description Omission of type specifiers may not be supported by some compilers.
+ * @kind problem
+ * @precision very-high
+ * @problem.severity error
+ * @tags external/cert/id/dcl31-c
+ *       correctness
+ *       readability
+ *       external/cert/obligation/rule
+ */
+
+import cpp
+import codingstandards.c.cert
+
+from Declaration d
+where
+  not isExcluded(d, Declarations1Package::declareIdentifiersBeforeUsingThemQuery()) and
+  exists(Specifier s | s = d.getASpecifier() and s.toString().regexpMatch("implicit_.*"))
+select d, "Declaration is missing a type specifier."

c/cert/test/rules/DCL31-C/DeclareIdentifiersBeforeUsingThem.expected

@@ -0,0 +1,2 @@
+| test.c:2:8:2:8 | g | Declaration is missing a type specifier. |
+| test.c:6:1:6:1 | f | Declaration is missing a type specifier. |

c/cert/test/rules/DCL31-C/DeclareIdentifiersBeforeUsingThem.qlref

@@ -0,0 +1 @@
+rules/DCL31-C/DeclareIdentifiersBeforeUsingThem.ql

c/cert/test/rules/DCL31-C/test.c

@@ -0,0 +1,12 @@
+
+extern g; //NON_COMPLIANT
+
+extern int g1; //COMPLIANT
+
+f(void) { //NON_COMPLIANT
+  return 1;
+}
+
+int f1(void) { //COMPLIANT
+  return 1;
+}

cpp/common/src/codingstandards/cpp/exclusions/c/Declarations1.qll

@@ -3,9 +3,19 @@ import cpp
 import RuleMetadata
 import codingstandards.cpp.exclusions.RuleMetadata
 
-newtype Declarations1Query = TDoNotDeclareOrDefineAReservedIdentifierQuery()
+newtype Declarations1Query =
+  TDeclareIdentifiersBeforeUsingThemQuery() or
+  TDoNotDeclareOrDefineAReservedIdentifierQuery()
 
 predicate isDeclarations1QueryMetadata(Query query, string queryId, string ruleId) {
+  query =
+    // `Query` instance for the `declareIdentifiersBeforeUsingThem` query
+    Declarations1Package::declareIdentifiersBeforeUsingThemQuery() and
+  queryId =
+    // `@id` for the `declareIdentifiersBeforeUsingThem` query
+    "c/cert/declare-identifiers-before-using-them" and
+  ruleId = "DCL31-C"
+  or
   query =
     // `Query` instance for the `doNotDeclareOrDefineAReservedIdentifier` query
     Declarations1Package::doNotDeclareOrDefineAReservedIdentifierQuery() and
@@ -16,6 +26,13 @@ predicate isDeclarations1QueryMetadata(Query query, string queryId, string ruleI
 }
 
 module Declarations1Package {
+  Query declareIdentifiersBeforeUsingThemQuery() {
+    //autogenerate `Query` type
+    result =
+      // `Query` type for `declareIdentifiersBeforeUsingThem` query
+      TQueryC(TDeclarations1PackageQuery(TDeclareIdentifiersBeforeUsingThemQuery()))
+  }
+
   Query doNotDeclareOrDefineAReservedIdentifierQuery() {
     //autogenerate `Query` type
     result =

rule_packages/c/Declarations1.json

@@ -1,5 +1,29 @@
 {
   "CERT-C": {
+    "DCL31-C": {
+      "properties": {
+        "obligation": "rule"
+      },
+      "queries": [
+        {
+          "description": "Omission of type specifiers may not be supported by some compilers.",
+          "kind": "problem",
+          "name": "Declare identifiers before using them",
+          "precision": "very-high",
+          "severity": "error",
+          "short_name": "DeclareIdentifiersBeforeUsingThem",
+          "tags": [
+            "correctness",
+            "readability" 
+          ],
+          "implementation_scope": {
+            "description": "This query does not check for implicit function declarations as this is partially compiler checked.",
+            "items": []
+          }
+        }
+      ],
+      "title": "Declare identifiers before using them"
+    },
     "DCL37-C": {
       "properties": {
         "obligation": "rule"

rules.csv

@@ -499,7 +499,7 @@ c,CERT-C,CON40-C,Yes,Rule,,,Do not refer to an atomic variable twice in an expre
 c,CERT-C,CON41-C,Yes,Rule,,,Wrap functions that can fail spuriously in a loop,CON53-CPP,Concurrency3,Medium,
 c,CERT-C,CON43-C,OutOfScope,Rule,,,Do not allow data races in multithreaded code,,,,
 c,CERT-C,DCL30-C,Yes,Rule,,,Declare objects with appropriate storage durations,,Declarations,Hard,
-c,CERT-C,DCL31-C,Yes,Rule,,,Declare identifiers before using them,,Declarations,Medium,
+c,CERT-C,DCL31-C,Yes,Rule,,,Declare identifiers before using them,,Declarations1,Medium,
 c,CERT-C,DCL36-C,Yes,Rule,,,Do not declare an identifier with conflicting linkage classifications,,Declarations,Medium,
 c,CERT-C,DCL37-C,Yes,Rule,,,Do not declare or define a reserved identifier,,Declarations1,Easy,
 c,CERT-C,DCL38-C,Yes,Rule,,,Use the correct syntax when declaring a flexible array member,,Declarations,Easy,