Merge pull request #562 from knewbury01/knewbury01/fix-82

A8-4-7: fix type size rounding error

Author: knewbury01

change_notes/2024-03-22-fix-fp-89-a8-4-7.md

@@ -0,0 +1,2 @@
+- `A8-4-7` - `InParametersForCheapToCopyTypesNotPassedByValue.ql`, `InParametersForCheapToCopyTypesNotPassedByReference.ql`:
+  - Fixes #89. Accidental floor rounding was applying to type size calculations.

cpp/autosar/src/rules/A8-4-7/TriviallyCopyableSmallType.qll

@@ -12,11 +12,11 @@ int wordSize() { result = max(VoidPointerType v | | v.getSize()) }
  * Converts bytes to words
  */
 bindingset[bytes]
-int bytesToWords(int bytes) { result = bytes / wordSize() }
+int minWordsRequiredToRepresentBytes(int bytes) { result = (1.0 * bytes / wordSize()).ceil() }
 
 class TriviallyCopyableSmallType extends Type {
   TriviallyCopyableSmallType() {
     isTriviallyCopyableType(this) and
-    exists(int size | size = this.getSize() | bytesToWords(size) <= 2)
+    exists(int size | size = this.getSize() | minWordsRequiredToRepresentBytes(size) <= 2)
   }
 }

cpp/autosar/test/rules/A8-4-7/test.cpp

@@ -68,4 +68,14 @@ struct S5 {
 
 void f15(S3 f15a) {} // COMPLIANT
 void f17(S4 f17a) {} // NON_COMPLIANT (S4 has a non-trivial destructor)
-void f18(S5 f18a) {} // COMPLIANT
+void f18(S5 f18a) {} // COMPLIANT
+
+#include <iostream>
+class A8_4_7 {
+public:
+  std::array<char, 20UL> values;
+};
+void fp_reported_in_82(
+    const A8_4_7 &a847) noexcept { // COMPLIANT - larger than 2 words
+  std::cout << a847.values[0] << std::endl;
+}