ValueFlow: don't reset the struct size if there is a unknown member + empty structs have a size of 1

Author: autoantwort

lib/valueflow.cpp

@@ -447,8 +447,6 @@ static size_t accumulateStructMembers(const Scope* scope, F f)
             else
                 total = f(total, *vt, dim);
         }
-        if (total == 0)
-            return 0;
     }
     return total;
 }
@@ -530,7 +528,7 @@ size_t ValueFlow::getSizeOf(const ValueType &vt, const Settings &settings, int m
             size_t n = ValueFlow::getSizeOf(vt2, settings, ++maxRecursion);
             size_t a = getAlignOf(vt2, settings);
             if (n == 0 || a == 0)
-                return 0;
+                return total;
             n *= dim;
             size_t padding = (a - (total % a)) % a;
             return vt.typeScope->type == ScopeType::eUnion ? std::max(total, n) : total + padding + n;
@@ -543,11 +541,10 @@ size_t ValueFlow::getSizeOf(const ValueType &vt, const Settings &settings, int m
                 return v;
             });
         }
-        if (total == 0)
-            return 0;
+        total = std::max(size_t{1}, total);
         size_t align = getAlignOf(vt, settings);
         if (align == 0)
-            return 0;
+            return total;
         total += (align - (total % align)) % align;
         return total;
     }

test/testvalueflow.cpp

@@ -1653,6 +1653,22 @@ class TestValueFlow : public TestFixture {
         ASSERT_EQUALS(1U, values.size());
         ASSERT_EQUALS(12, values.back().intvalue);
 
+        code = "struct X { A a; int b; A c; };\n"
+               "void f() {\n"
+               "    x = sizeof(X);\n"
+               "}";
+        values = tokenValues(code, "( X )");
+        ASSERT_EQUALS(1U, values.size());
+        ASSERT_EQUALS(4, values.back().intvalue);
+
+        code = "struct X {};\n"
+               "void f() {\n"
+               "    x = sizeof(X);\n"
+               "}";
+        values = tokenValues(code, "( X )");
+        ASSERT_EQUALS(1U, values.size());
+        ASSERT_EQUALS(1, values.back().intvalue);
+
         code = "struct T;\n"
                "struct S { T& r; };\n"
                "struct T { S s{ *this }; };\n"