Add trigraph rule RULE-5-0-1 #1022

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Merged

knewbury01 merged 5 commits into github:main from knewbury01:knewbury01/trigraphs

Feb 3, 2026

.vscode/tasks.json

-Original file line number
+Diff line change
@@ Expand Up / @@ -290,6 +290,7 @@ @@
                     "Strings3",
                     "Syntax",
                     "Templates",
+                    "Trigraph",
                     "TypeRanges",
                     "Lambdas",
                     "Pointers",
@@ Expand Down @@

cpp/common/src/codingstandards/cpp/exclusions/cpp/RuleMetadata.qll

-Original file line number
+Diff line change
@@ Expand Up / @@ -59,6 +59,7 @@ import Statements @@
     import Strings
     import Templates
     import Toolchain
+    import Trigraph
     import TrustBoundaries
     import TypeRanges
     import Uninitialized
@@ Expand Down Expand Up / @@ -123,6 +124,7 @@ newtype TCPPQuery = @@
       TStringsPackageQuery(StringsQuery q) or
       TTemplatesPackageQuery(TemplatesQuery q) or
       TToolchainPackageQuery(ToolchainQuery q) or
+      TTrigraphPackageQuery(TrigraphQuery q) or
       TTrustBoundariesPackageQuery(TrustBoundariesQuery q) or
       TTypeRangesPackageQuery(TypeRangesQuery q) or
       TUninitializedPackageQuery(UninitializedQuery q) or
@@ Expand Down Expand Up @@
       isStringsQueryMetadata(query, queryId, ruleId, category) or
       isTemplatesQueryMetadata(query, queryId, ruleId, category) or
       isToolchainQueryMetadata(query, queryId, ruleId, category) or
+      isTrigraphQueryMetadata(query, queryId, ruleId, category) or
       isTrustBoundariesQueryMetadata(query, queryId, ruleId, category) or
       isTypeRangesQueryMetadata(query, queryId, ruleId, category) or
       isUninitializedQueryMetadata(query, queryId, ruleId, category) or
@@ Expand Down @@

cpp/common/src/codingstandards/cpp/exclusions/cpp/Trigraph.qll

-Original file line number
+Diff line change
@@ -0,0 +1,26 @@
+    //** THIS FILE IS AUTOGENERATED, DO NOT MODIFY DIRECTLY.  **/
+    import cpp
+    import RuleMetadata
+    import codingstandards.cpp.exclusions.RuleMetadata
+    newtype TrigraphQuery = TTrigraphLikeSequencesShouldNotBeUsedQuery()
+    predicate isTrigraphQueryMetadata(Query query, string queryId, string ruleId, string category) {
+      query =
+        // `Query` instance for the `trigraphLikeSequencesShouldNotBeUsed` query
+        TrigraphPackage::trigraphLikeSequencesShouldNotBeUsedQuery() and
+      queryId =
+        // `@id` for the `trigraphLikeSequencesShouldNotBeUsed` query
+        "cpp/misra/trigraph-like-sequences-should-not-be-used" and
+      ruleId = "RULE-5-0-1" and
+      category = "advisory"
+    }
+    module TrigraphPackage {
+      Query trigraphLikeSequencesShouldNotBeUsedQuery() {
+        //autogenerate `Query` type
+        result =
+          // `Query` type for `trigraphLikeSequencesShouldNotBeUsed` query
+          TQueryCPP(TTrigraphPackageQuery(TTrigraphLikeSequencesShouldNotBeUsedQuery()))
+      }
+    }

cpp/misra/src/rules/RULE-5-0-1/TrigraphLikeSequencesShouldNotBeUsed.ql

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+Diff line change
@@ -0,0 +1,43 @@
+    /**
+     * @id cpp/misra/trigraph-like-sequences-should-not-be-used
+     * @name RULE-5-0-1: Trigraph-like sequences should not be used
+     * @description Using trigraph-like sequences can lead to developer confusion.
+     * @kind problem
+     * @precision medium
+     * @problem.severity warning
+     * @tags external/misra/id/rule-5-0-1
+     *       maintainability
+     *       readability
+     *       scope/single-translation-unit
+     *       external/misra/enforcement/decidable
+     *       external/misra/obligation/advisory
+     */
+    import cpp
+    import codingstandards.cpp.misra
+    class CanContainSequenceType extends Locatable {
+      CanContainSequenceType() {
+        this instanceof StringLiteral
+        or
+        this instanceof Comment
+        or
+        this instanceof Macro
+      }
+      string getContent() {
+        result = this.(StringLiteral).getValue()
+        or
+        result = this.(Comment).getContents()
+        or
+        result = this.(Macro).getBody()
+      }
+    }
+    from CanContainSequenceType s, int occurrenceOffset, string substring
+    where
+      not isExcluded(s, TrigraphPackage::trigraphLikeSequencesShouldNotBeUsedQuery()) and
+      substring = s.getContent().regexpFind("\\?\\?[=/'()!<>-]", _, occurrenceOffset) and
+      //one escape character is enough to mean this isnt a trigraph-like sequence
+      not exists(s.(StringLiteral).getASimpleEscapeSequence(_, occurrenceOffset + 1))
+    select s, "Trigraph-like sequence found: '" + substring + "'."

cpp/misra/test/rules/RULE-5-0-1/TrigraphLikeSequencesShouldNotBeUsed.expected

-Original file line number
+Diff line change
@@ -0,0 +1,11 @@
+    | test.cpp:1:17:1:21 | ??= | Trigraph-like sequence found: '??='. |
+    | test.cpp:2:18:2:22 | ??/ | Trigraph-like sequence found: '??/'. |
+    | test.cpp:3:18:3:22 | ??' | Trigraph-like sequence found: '??''. |
+    | test.cpp:4:18:4:22 | ??( | Trigraph-like sequence found: '??('. |
+    | test.cpp:5:18:5:22 | ??) | Trigraph-like sequence found: '??)'. |
+    | test.cpp:6:18:6:22 | ??! | Trigraph-like sequence found: '??!'. |
+    | test.cpp:7:18:7:22 | ??< | Trigraph-like sequence found: '??<'. |
+    | test.cpp:8:18:8:22 | ??> | Trigraph-like sequence found: '??>'. |
+    | test.cpp:9:18:9:22 | ??- | Trigraph-like sequence found: '??-'. |
+    | test.cpp:14:1:14:45 | // comment trigraph-like ??= // NON_COMPLIANT | Trigraph-like sequence found: '??='. |
+    | test.cpp:17:1:17:25 | #define TRIGRAPH_LIKE ??= | Trigraph-like sequence found: '??='. |

cpp/misra/test/rules/RULE-5-0-1/TrigraphLikeSequencesShouldNotBeUsed.qlref

Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		rules/RULE-5-0-1/TrigraphLikeSequencesShouldNotBeUsed.ql

cpp/misra/test/rules/RULE-5-0-1/test.cpp

-Original file line number
+Diff line change
@@ -0,0 +1,17 @@
+    const char *g = "??=";  // NON_COMPLIANT
+    const char *g1 = "??/"; // NON_COMPLIANT
+    const char *g2 = "??'"; // NON_COMPLIANT
+    const char *g3 = "??("; // NON_COMPLIANT
+    const char *g4 = "??)"; // NON_COMPLIANT
+    const char *g5 = "??!"; // NON_COMPLIANT
+    const char *g6 = "??<"; // NON_COMPLIANT
+    const char *g7 = "??>"; // NON_COMPLIANT
+    const char *g8 = "??-"; // NON_COMPLIANT
+    const char *g9 = "\?\?="; // COMPLIANT
+    const char *g10 = "?=";   // COMPLIANT
+    // comment trigraph-like ??= // NON_COMPLIANT
+    // clang-format off
+    #define TRIGRAPH_LIKE ??= // NON_COMPLIANT - format off otherwise it separates the characters

rule_packages/cpp/Trigraph.json

-Original file line number
+Diff line change
@@ -0,0 +1,29 @@
+    {
+      "MISRA-C++-2023": {
+        "RULE-5-0-1": {
+          "properties": {
+            "enforcement": "decidable",
+            "obligation": "advisory"
+          },
+          "queries": [
+            {
+              "description": "Using trigraph-like sequences can lead to developer confusion.",
+              "kind": "problem",
+              "name": "Trigraph-like sequences should not be used",
+              "precision": "medium",
+              "severity": "warning",
+              "short_name": "TrigraphLikeSequencesShouldNotBeUsed",
+              "tags": [
+                "maintainability",
+                "readability",
+                "scope/single-translation-unit"
+              ],
+              "implementation_scope": {
+                "description": "The rule checks within string literals only for trigraph-like sequences."
+              }
+            }
+          ],
+          "title": "Trigraph-like sequences should not be used"
+        }
+      }
+    }

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