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Merge pull request #784 from github/michaelrfairhurst/implement-deadcode-2-unused-object-definitions
Implement RULE-2-8, project should not contain unused object definitions
2 parents 8736ca7 + 3566e0f commit f4e10dc

22 files changed

+958
-17
lines changed

‎c/misra/src/codeql-suites/misra-c-default.qls

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- exclude:
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tags contain:
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- external/misra/audit
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- external/misra/strict
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- external/misra/default-disabled

‎c/misra/src/codeql-suites/misra-c-strict.qls

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- description: MISRA C 2012 (Strict)
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- qlpack: codeql/misra-c-coding-standards
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- include:
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kind:
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- problem
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- path-problem
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tags contain:
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- external/misra/strict

‎c/misra/src/rules/RULE-2-8/UnusedObjectDefinition.ql

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/**
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* @id c/misra/unused-object-definition
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* @name RULE-2-8: A project should not contain unused object definitions
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* @description Object definitions which are unused should be removed.
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* @kind problem
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* @precision very-high
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* @problem.severity recommendation
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* @tags external/misra/id/rule-2-8
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* maintainability
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* performance
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* external/misra/c/2012/amendment4
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* external/misra/obligation/advisory
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*/
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import cpp
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import codingstandards.c.misra
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import codingstandards.cpp.deadcode.UnusedObjects
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from ReportDeadObject report
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where
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not isExcluded(report.getPrimaryElement(), DeadCode2Package::unusedObjectDefinitionQuery()) and
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not report.hasAttrUnused()
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select report.getPrimaryElement(), report.getMessage(), report.getOptionalPlaceholderLocation(),
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report.getOptionalPlaceholderMessage()

‎c/misra/src/rules/RULE-2-8/UnusedObjectDefinitionStrict.ql

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/**
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* @id c/misra/unused-object-definition-strict
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* @name RULE-2-8: A project should not contain '__attribute__((unused))' object definitions
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* @description A strict query which reports all unused object definitions with
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* '__attribute__((unused))'.
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* @kind problem
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* @precision very-high
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* @problem.severity recommendation
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* @tags external/misra/id/rule-2-8
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* maintainability
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* performance
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* external/misra/c/2012/amendment4
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* external/misra/c/strict
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* external/misra/obligation/advisory
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*/
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import cpp
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import codingstandards.c.misra
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import codingstandards.cpp.deadcode.UnusedObjects
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from ReportDeadObject report
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where
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not isExcluded(report.getPrimaryElement(), DeadCode2Package::unusedObjectDefinitionStrictQuery()) and
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report.hasAttrUnused()
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select report.getPrimaryElement(), report.getMessage(), report.getOptionalPlaceholderLocation(),
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report.getOptionalPlaceholderMessage()

‎c/misra/test/rules/RULE-2-8/UnusedObjectDefinition.expected

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| test.c:6:5:6:6 | definition of g2 | Unused object 'g2'. | test.c:6:5:6:6 | test.c:6:5:6:6 | (ignored) |
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| test.c:9:5:9:6 | definition of g3 | Unused object 'g3'. | test.c:9:5:9:6 | test.c:9:5:9:6 | (ignored) |
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| test.c:20:7:20:8 | definition of l2 | Unused object 'l2'. | test.c:20:7:20:8 | test.c:20:7:20:8 | (ignored) |
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| test.c:27:7:27:8 | definition of l5 | Unused object 'l5'. | test.c:27:7:27:8 | test.c:27:7:27:8 | (ignored) |
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| test.c:37:10:37:11 | definition of g5 | Unused object 'g5'. | test.c:37:10:37:11 | test.c:37:10:37:11 | (ignored) |
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| test.c:45:9:45:10 | definition of g6 | Unused object 'g6'. | test.c:45:9:45:10 | test.c:45:9:45:10 | (ignored) |
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| test.c:51:5:51:6 | definition of g7 | Unused object 'g7'. | test.c:51:5:51:6 | test.c:51:5:51:6 | (ignored) |
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| test.c:64:3:64:18 | ONLY_DEF_VAR(x) | Invocation of macro '$@' defines unused object 'l2'. | test.c:60:1:60:34 | test.c:60:1:60:34 | ONLY_DEF_VAR |
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| test.c:68:1:71:5 | #define ALSO_DEF_VAR(x) int x = 0; while (1) ; | Macro 'ALSO_DEF_VAR' defines unused object with an invocation-dependent name, for example, '$@'. | test.c:73:16:73:17 | test.c:73:16:73:17 | l1 |
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| test.c:77:1:82:3 | #define DEF_UNUSED_INNER_VAR() { int _v = 0; while (1) ; } | Macro 'DEF_UNUSED_INNER_VAR' defines unused object '_v'. | test.c:77:1:82:3 | test.c:77:1:82:3 | (ignored) |
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| test.c:119:11:119:13 | definition of g10 | Unused object 'g10'. | test.c:119:11:119:13 | test.c:119:11:119:13 | (ignored) |
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| test.c:124:13:124:14 | definition of l2 | Unused object 'l2'. | test.c:124:13:124:14 | test.c:124:13:124:14 | (ignored) |

‎c/misra/test/rules/RULE-2-8/UnusedObjectDefinition.qlref

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rules/RULE-2-8/UnusedObjectDefinition.ql

‎c/misra/test/rules/RULE-2-8/UnusedObjectDefinitionStrict.expected

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| test.c:87:29:87:30 | definition of g8 | Unused object 'g8'. | test.c:87:29:87:30 | test.c:87:29:87:30 | (ignored) |
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| test.c:92:3:92:30 | ONLY_DEF_ATTR_UNUSED_VAR(x) | Invocation of macro '$@' defines unused object 'l2'. | test.c:88:1:88:70 | test.c:88:1:88:70 | ONLY_DEF_ATTR_UNUSED_VAR |
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| test.c:96:1:99:5 | #define ALSO_DEF_ATTR_UNUSED_VAR(x) __attribute__((unused)) int x = 0; while (1) ; | Macro 'ALSO_DEF_ATTR_UNUSED_VAR' defines unused object with an invocation-dependent name, for example, '$@'. | test.c:101:28:101:29 | test.c:101:28:101:29 | l1 |
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| test.c:106:1:111:3 | #define DEF_ATTR_UNUSED_INNER_VAR() { __attribute__((unused)) int _v = 0; while (1) ; } | Macro 'DEF_ATTR_UNUSED_INNER_VAR' defines unused object '_v'. | test.c:106:1:111:3 | test.c:106:1:111:3 | (ignored) |

‎c/misra/test/rules/RULE-2-8/UnusedObjectDefinitionStrict.qlref

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rules/RULE-2-8/UnusedObjectDefinitionStrict.ql

‎c/misra/test/rules/RULE-2-8/test.c

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// Not a definition, only a declaration:
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extern int g1; // COMPLIANT
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// Both declared + defined:
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extern int g2; // COMPLIANT
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int g2 = 1; // NON_COMPLIANT
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// Definition is only declaration:
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int g3 = 1; // NON_COMPLIANT
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// Definition, but value is required for program to compile:
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int g4 = 1; // COMPLIANT
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void f1() { g4; }
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// Local variables:
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void f2() {
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int l1; // COMPLIANT
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l1;
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int l2; // NON-COMPLIANT
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// Value is required for the program to compile:
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int l3; // COMPLIANT
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sizeof(l3);
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int l4, // COMPLIANT
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l5; // NON-COMPLIANT
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l4;
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}
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// Struct fields are not objects:
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struct s {
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int x; // COMPLIANT
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};
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// Declaration of type struct is an object:
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struct s g5; // NON-COMPLIANT
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// Struct fields are not objects:
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union u {
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int x; // COMPLIANT
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};
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// Declaration of type union is an object:
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union u g6; // NON-COMPLIANT
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// Typedefs are not objects:
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typedef int td1; // COMPLIANT
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// Declaration of typedef type object:
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td1 g7; // NON-COMPLIANT
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// Function parameters are not objects:
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void f3(int p) {} // COMPLIANT
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// Function type parameters are not objects:
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typedef int td2(int x); // COMPLIANT
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// Macros that define unused vars tests:
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#define ONLY_DEF_VAR(x) int x = 0;
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void f4() {
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ONLY_DEF_VAR(l1); // COMPLIANT
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l1;
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ONLY_DEF_VAR(l2); // NON-COMPLIANT
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}
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// NON-COMPLIANT
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#define ALSO_DEF_VAR(x) \
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int x = 0; \
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while (1) \
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;
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void f5() {
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ALSO_DEF_VAR(l1); // COMPLIANT
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ALSO_DEF_VAR(l2); // COMPLIANT
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}
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#define DEF_UNUSED_INNER_VAR() \
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{ \
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int _v = 0; \
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while (1) \
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; \
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} // NON-COMPLIANT
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void f6() {
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DEF_UNUSED_INNER_VAR(); // COMPLIANT
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}
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__attribute__((unused)) int g8 = 1; // NON-COMPLIANT
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#define ONLY_DEF_ATTR_UNUSED_VAR(x) __attribute__((unused)) int x = 0;
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void f7() {
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ONLY_DEF_ATTR_UNUSED_VAR(l1); // COMPLIANT
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l1;
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ONLY_DEF_ATTR_UNUSED_VAR(l2); // NON-COMPLIANT
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}
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// NON-COMPLIANT
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#define ALSO_DEF_ATTR_UNUSED_VAR(x) \
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__attribute__((unused)) int x = 0; \
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while (1) \
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;
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void f8() {
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ALSO_DEF_ATTR_UNUSED_VAR(l1); // COMPLIANT
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ALSO_DEF_ATTR_UNUSED_VAR(l2); // COMPLIANT
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}
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// NON-COMPLIANT
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#define DEF_ATTR_UNUSED_INNER_VAR() \
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{ \
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__attribute__((unused)) int _v = 0; \
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while (1) \
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; \
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}
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void f9() {
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DEF_ATTR_UNUSED_INNER_VAR(); // COMPLIANT
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}
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// Const variable tests:
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const int g9 = 1; // COMPLIANT
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const int g10 = 1; // NON-COMPLIANT
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void f10() {
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g9;
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const int l1 = 1; // COMPLIANT
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const int l2 = 1; // NON-COMPLIANT
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l1;
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}
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// Side effects should not disable this rule:
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void f11() {
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int l1 = 1; // COMPLIANT
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int l2 = l1++; // COMPLIANT
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l2;
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}

‎cpp/common/src/codingstandards/cpp/AlertReporting.qll

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}
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2020
/**
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* Gets the primary macro that generated the result element.
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* Gets the primary macro invocation that generated the result element.
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*/
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Macro getPrimaryMacro(ResultElement re) {
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MacroInvocation getPrimaryMacroInvocation(ResultElement re) {
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exists(MacroInvocation mi |
2525
mi = getAMacroInvocation(re) and
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// No other more specific macro that expands to element
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not exists(MacroInvocation otherMi |
2828
otherMi = getAMacroInvocation(re) and otherMi.getParentInvocation() = mi
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) and
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result = mi.getMacro()
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result = mi
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)
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}
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/**
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* Gets the primary macro that generated the result element.
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*/
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Macro getPrimaryMacro(ResultElement re) { result = getPrimaryMacroInvocation(re).getMacro() }
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/**
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* If a result element is expanded from a macro invocation, then return the "primary" macro that
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* generated the element, otherwise return the element itself.
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*/
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Element unwrapElement(ResultElement re) {
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if exists(getPrimaryMacro(re)) then result = getPrimaryMacro(re) else result = re
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}
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/* Final class so we can extend it */
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final private class FinalMacroInvocation = MacroInvocation;
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/* A macro invocation that expands to create a `ResultElement` */
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class ResultMacroExpansion extends FinalMacroInvocation {
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ResultElement re;
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ResultMacroExpansion() { re = getAnExpandedElement() }
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ResultElement getResultElement() { result = re }
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}
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/* The most specific macro invocation that expands to create this `ResultElement`. */
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class PrimaryMacroExpansion extends ResultMacroExpansion {
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PrimaryMacroExpansion() { this = getPrimaryMacroInvocation(re) }
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}
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}

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