Closes #33

core/dbc_diagnostic.h

@@ -22,7 +22,8 @@ enum class DbcDiagnosticCode {
     InvalidMultiplexing,
     UnsupportedStatement,
     InvalidAttribute,
-    UnsupportedAttribute
+    UnsupportedAttribute,
+    UnsupportedSignalType
 };
 
 /** @brief Diagnostic message and physical source location. */

core/dbc_parser.cpp

@@ -83,6 +83,8 @@ namespace {
             return DbcDiagnosticCode::InvalidMultiplexing;
         if (keyword == "VAL_")
             return DbcDiagnosticCode::InvalidValueDescription;
+        if (keyword == "SIG_VALTYPE_")
+            return DbcDiagnosticCode::UnsupportedSignalType;
         return DbcDiagnosticCode::InvalidStatement;
     }
 }

core/dbc_parser.h

@@ -37,7 +37,9 @@ struct DbcParserOptions {
  * Attribute statements support multiline fields and quoted strings, ending at
  * a semicolon outside quoted text. Diagnostics use the first physical line.
  *
- * Reports unsupported statements as warnings. Invalid multiplexing is
+ * Rejects all SIG_VALTYPE_ declarations, including type 0, with
+ * UnsupportedSignalType errors; explicit signal value types are not implemented.
+ * Other unsupported statements produce warnings. Invalid multiplexing is
  * an error. VERSION, NS_, BS_, BU_ and NS_ symbol declarations stay quiet.
  */
 class DbcParser {
@@ -49,7 +51,7 @@ public:
      * @brief Parse DBC file.
      * @param filePath Path to input file.
      * @return Parsed database.
-     * @throws std::runtime_error on file or parse errors.
+     * @throws std::runtime_error on file or parse errors, including SIG_VALTYPE_.
      * Line parse errors include the file path and one-based line number.
      * Duplicate normalized CAN IDs of the same frame type and duplicate signal
      * names within a frame are rejected at the repeated definition's line.

core/dbc_statement_handler.cpp

@@ -411,6 +411,7 @@ DbcStatementDispatcher::DbcStatementDispatcher() {
     RegisterType<DbcMultiplexingHandler>("SG_MUL_VAL_");
     RegisterType<DbcFrameHandler>("BO_");
     RegisterType<DbcSignalHandler>("SG_");
+    RegisterType<DbcUnsupportedSignalTypeHandler>("SIG_VALTYPE_");
     RegisterType<DbcCommentHandler>("CM_");
     RegisterType<DbcValueDescriptionHandler>("VAL_");
     RegisterType<DbcAttributeHandler>("BA_DEF_");
@@ -418,6 +419,10 @@ DbcStatementDispatcher::DbcStatementDispatcher() {
     RegisterType<DbcAttributeHandler>("BA_");
 }
 
+void DbcUnsupportedSignalTypeHandler::Handle(const std::string &, DbcParseContext &) const {
+    throw std::runtime_error("SIG_VALTYPE_ declarations are unsupported; refusing potentially incorrect integer decoding.");
+}
+
 void DbcHeaderHandler::Handle(const std::string &, DbcParseContext &) const {}
 
 bool DbcStatementDispatcher::Dispatch(const std::string &line,

core/dbc_statement_handler.h

@@ -133,6 +133,12 @@ public:
     void Handle(const std::string &line, DbcParseContext &context) const override;
 };
 
+/** Reject explicit signal value types instead of treating their bits as integers. */
+class DbcUnsupportedSignalTypeHandler : public DbcStatementHandler {
+public:
+    void Handle(const std::string &line, DbcParseContext &context) const override;
+};
+
 /** Common header metadata does not change the supported decode definitions. */
 class DbcHeaderHandler : public DbcStatementHandler {
 public: