simple bailout for structured binding

danmar · Jan 5, 2025 · 4793d2a · 4793d2a
1 parent 2179f04
commit 4793d2a
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Showing 2 changed files with 22 additions and 29 deletions.
diff --git a/lib/checkunusedvar.cpp b/lib/checkunusedvar.cpp
@@ -1534,34 +1534,29 @@ void CheckUnusedVar::checkStructMemberUsage()
         if (bailout)
             continue;
 
-        // Structured binding assigned to variable
-        std::vector<nonneg int> structBindUsage;
-        for (const Token *tok = mTokenizer->tokens(); tok; tok = tok->next()) {
-            if (!Token::Match(tok, "] %assign% %var%"))
+        // Bailout if struct is used in structured binding
+        for (const Variable *var : symbolDatabase->variableList()) {
+            if (!var || !Token::simpleMatch(var->typeStartToken(), "auto"))
                 continue;
 
-            const Variable *const var = tok->tokAt(2)->variable();
-            if (!var || var->type()->classScope != &scope)
+            const Token *tok = var->nameToken()->previous();
+            if (!Token::simpleMatch(tok, "["))
                 continue;
 
-            const Token *const startBracket = tok->link();
-            if (!startBracket ||
-                (!Token::Match(startBracket->tokAt(-2), "auto &|&&") &&
-                 !Token::simpleMatch(startBracket->previous(), "auto")))
+            tok = tok->link();
+            if (!Token::Match(tok, "] %assign%"))
                 continue;
 
-            std::size_t bindCount = 1;
-            const Token *comma = startBracket->astOperand2();
-            while (Token::simpleMatch(comma, ",")) {
-                ++bindCount;
-                comma = comma->astOperand1();
-            }
+            tok = tok->next()->astOperand2();
+            const ValueType *valueType = tok->valueType();
 
-            auto end = scope.varlist.cbegin();
-            std::advance(end, bindCount);
-            for (auto it = scope.varlist.cbegin(); it != end; ++it)
-                structBindUsage.push_back(it->index());
+            if (valueType && valueType->typeScope == &scope) {
+                bailout = true;
+                break;
+            }
         }
+        if (bailout)
+            continue;
 
         for (const Variable &var : scope.varlist) {
             // only warn for variables without side effects
@@ -1570,9 +1565,6 @@ void CheckUnusedVar::checkStructMemberUsage()
             if (isInherited && !var.isPrivate())
                 continue;
 
-            if (std::find(structBindUsage.cbegin(), structBindUsage.cend(), var.index()) != structBindUsage.cend())
-                continue;
-
             // Check if the struct member variable is used anywhere in the file
             bool use = false;
             for (const Token *tok = mTokenizer->tokens(); tok; tok = tok->next()) {

diff --git a/test/testunusedvar.cpp b/test/testunusedvar.cpp
@@ -2036,13 +2036,14 @@ class TestUnusedVar : public TestFixture {
         ASSERT_EQUALS("", errout_str());
 
         checkStructMemberUsage("struct S { int a, b; };\n"
-                               "S f() {\n"
-                               "    S s{};\n"
-                               "    auto& [x] = s;\n"
-                               "    x = 1;\n"
-                               "    return s;\n"
+                               "struct T { S s; };\n"
+                               "T f() {\n"
+                               "    T t{};\n"
+                               "    auto& [x, y] = t.s;\n"
+                               "    x = y = 1;\n"
+                               "    return t;\n"
                                "}\n");
-        ASSERT_EQUALS("[test.cpp:1]: (style) struct member 'S::b' is never used.\n", errout_str());
+        ASSERT_EQUALS("", errout_str());
     }
 
     void functionVariableUsage_(const char* file, int line, const char code[], bool cpp = true) {