Merge pull request #868 from github/lcartey/rule-8-7

`RULE-8-7`: Report external identifiers only referenced in single translation units

Author: lcartey

c/misra/src/rules/RULE-8-7/ShouldNotBeDefinedWithExternalLinkage.ql

@@ -40,17 +40,22 @@ predicate isReferencedInTranslationUnit(
   ExternalIdentifiers e, ExternalIdentifierReference r, TranslationUnit t
 ) {
   r.getExternalIdentifierTarget() = e and
-  r.getFile() = t
+  // Used within the translation unit or an included header
+  r.getFile() = t.getAUserFile()
 }
 
 from ExternalIdentifiers e, ExternalIdentifierReference a1, TranslationUnit t1
 where
   not isExcluded(e, Declarations6Package::shouldNotBeDefinedWithExternalLinkageQuery()) and
+  // Only report external identifiers where we see the definition
+  e.hasDefinition() and
   isReferencedInTranslationUnit(e, a1, t1) and
   // Not referenced in any other translation unit
   not exists(TranslationUnit t2 |
     isReferencedInTranslationUnit(e, _, t2) and
     not t1 = t2
-  )
+  ) and
+  // Definition is also in the same translation unit
+  e.getDefinition().getFile() = t1.getAUserFile()
 select e, "Declaration with external linkage is accessed in only one translation unit $@.", a1,
   a1.toString()

c/misra/test/rules/RULE-8-7/ShouldNotBeDefinedWithExternalLinkage.expected

@@ -1,3 +1,4 @@
-| test.h:2:12:2:13 | i1 | Declaration with external linkage is accessed in only one translation unit $@. | test.c:4:3:4:4 | i1 | i1 |
-| test.h:3:5:3:6 | i2 | Declaration with external linkage is accessed in only one translation unit $@. | test.c:5:3:5:4 | i2 | i2 |
-| test.h:5:13:5:14 | f2 | Declaration with external linkage is accessed in only one translation unit $@. | test.c:7:3:7:4 | call to f2 | call to f2 |
+| test2.h:2:13:2:14 | f6 | Declaration with external linkage is accessed in only one translation unit $@. | test2.h:3:22:3:23 | call to f6 | call to f6 |
+| test.c:3:5:3:6 | i1 | Declaration with external linkage is accessed in only one translation unit $@. | test.c:11:3:11:4 | i1 | i1 |
+| test.c:4:5:4:6 | i2 | Declaration with external linkage is accessed in only one translation unit $@. | test.c:12:3:12:4 | i2 | i2 |
+| test.c:6:6:6:7 | f2 | Declaration with external linkage is accessed in only one translation unit $@. | test.c:14:3:14:4 | call to f2 | call to f2 |

c/misra/test/rules/RULE-8-7/test.c

@@ -1,4 +1,11 @@
 #include "test.h"
+int i = 0;
+int i1 = 0;
+int i2;             // NON_COMPLIANT - accessed one translation unit
+void f1() {}        // Definition
+void f2() {}        // Definition
+static void f3(){}; // COMPLIANT - internal linkage
+void f4() {}        // Definition
 void f() {
   i = 0;
   i1 = 0;

c/misra/test/rules/RULE-8-7/test.h

@@ -1,7 +1,6 @@
 extern int i;     // COMPLIANT - accessed multiple translation units
 extern int i1;    // NON_COMPLIANT - accessed one translation unit
-int i2;           // NON_COMPLIANT - accessed one translation unit
 extern void f1(); // COMPLIANT  - accessed multiple translation units
 extern void f2(); // NON_COMPLIANT - accessed one translation unit
-static void f3(); // COMPLIANT - internal linkage
-extern void f3(); // COMPLIANT - internal linkage
+extern void f4(); // COMPLIANT - accessed across translation units
+extern void f5(); // COMPLIANT - no definition

c/misra/test/rules/RULE-8-7/test1.c

@@ -1,5 +1,7 @@
-#include "test.h"
+#include "test2.h"
 void f() {
   i = 0;
   f1();
+  f4();
+  f5();
 }

c/misra/test/rules/RULE-8-7/test2.h

@@ -0,0 +1,3 @@
+#include "test.h"
+extern void f6() {} // NON_COMPLIANT
+static void test() { f6(); }

change_notes/2025-03-09-rule-8-7.md

@@ -0,0 +1,4 @@
+ - `RULE-8-7` - `ShouldNotBeDefinedWithExternalLinkage.ql`:
+   - Remove false positives where the declaration is not defined in the database.
+   - Remove false positives where the definition and reference are in different translation units.
+   - Remove false positives where the reference occurs in a header file.