Fix 14137: False positive: uninitvar when using an assert before loop (#7828)

Author: pfultz2

lib/programmemory.cpp

@@ -441,6 +441,16 @@ static void fillProgramMemoryFromAssignments(ProgramMemory& pm, const Token* tok
                     pm.setValue(vartok, execute(valuetok, pm, settings));
                 }
             }
+        } else if (Token::simpleMatch(tok2, ")") && tok2->link() &&
+                   Token::Match(tok2->link()->previous(), "assert|ASSERT ( !!)")) {
+            const Token* cond = tok2->link()->astOperand2();
+            if (!conditionIsTrue(cond, state, settings)) {
+                // TODO: change to assert when we can propagate the assert, for now just bail
+                if (conditionIsFalse(cond, state, settings))
+                    return;
+                programMemoryParseCondition(pm, cond, nullptr, settings, true);
+            }
+            tok2 = tok2->link()->previous();
         } else if (tok2->exprId() > 0 && Token::Match(tok2, ".|(|[|*|%var%") && !pm.hasValue(tok2->exprId()) &&
                    isVariableChanged(tok2, 0, settings)) {
             pm.setUnknown(tok2);

test/testuninitvar.cpp

@@ -7667,6 +7667,16 @@ class TestUninitVar : public TestFixture {
                         "    }\n"
                         "}\n");
         ASSERT_EQUALS("[test.cpp:3:24]: (error) Uninitialized variable: b [uninitvar]\n", errout_str());
+
+        // #14137
+        valueFlowUninit("int f(int n) {\n"
+                        "    int x;\n"
+                        "    assert(n > 0);\n"
+                        "    for(int i=0;i<n;i++)\n"
+                        "        x = n;\n"
+                        "    return x;\n"
+                        "}\n");
+        ASSERT_EQUALS("", errout_str());
     }
 
     void uninitvar_memberfunction() {