Rule 15.5: Improvements

 * Exclude compiler generated return statements
 * Exclude functions with more than one block
 * Improve alert message
 * Only report that the last statement is not a return, if there's at
least one return statement in the block.

Author: lcartey

c/misra/src/rules/RULE-15-5/FunctionReturnCondition.ql

@@ -15,16 +15,29 @@
 import cpp
 import codingstandards.c.misra
 
-from Function func, string message
+class UserWrittenReturnStmt extends ReturnStmt {
+  UserWrittenReturnStmt() { not this.isCompilerGenerated() }
+}
+
+from Function func, string message, UserWrittenReturnStmt returnStmt
 where
   not isExcluded(func, Statements5Package::functionReturnConditionQuery()) and
   func.hasDefinition() and
+  // Ignore functions which have multiple bodies
+  count(func.getBlock()) = 1 and
+  // Ignore functions which are compiler generated
   not func.isCompilerGenerated() and
+  // Report all the return statements in the function
+  returnStmt.getEnclosingFunction() = func and
   (
-    count(ReturnStmt return | return.getEnclosingFunction() = func) > 1 and
-    message = "Function has more than on return statement."
+    // There is more than one return statement
+    count(UserWrittenReturnStmt return | return.getEnclosingFunction() = func) > 1 and
+    message = "Function has more than one $@."
     or
-    not func.getBlock().getLastStmt() instanceof ReturnStmt and
-    message = "The last statement of the function is not a return statement."
+    // There is exactly one return statement
+    count(UserWrittenReturnStmt return | return.getEnclosingFunction() = func) = 1 and
+    // But it is not the last statement in the function
+    not func.getBlock().getLastStmt() instanceof UserWrittenReturnStmt and
+    message = "The $@ is not the last statement of the function."
   )
-select func, message
+select func, message, returnStmt, "return statement"

c/misra/test/rules/RULE-15-5/FunctionReturnCondition.expected

@@ -1,4 +1,5 @@
-| test.c:1:6:1:7 | f1 | Function has more than on return statement. |
-| test.c:14:6:14:7 | f3 | The last statement of the function is not a return statement. |
-| test.c:21:6:21:7 | f4 | Function has more than on return statement. |
-| test.c:21:6:21:7 | f4 | The last statement of the function is not a return statement. |
+| test.c:1:6:1:7 | f1 | Function has more than one $@. | test.c:3:5:3:11 | return ... | return statement |
+| test.c:1:6:1:7 | f1 | Function has more than one $@. | test.c:5:3:5:9 | return ... | return statement |
+| test.c:14:6:14:7 | f3 | The $@ is not the last statement of the function. | test.c:17:3:17:9 | return ... | return statement |
+| test.c:21:6:21:7 | f4 | Function has more than one $@. | test.c:23:5:23:11 | return ... | return statement |
+| test.c:21:6:21:7 | f4 | Function has more than one $@. | test.c:25:3:25:9 | return ... | return statement |