fixup! fixup! Fix #1473: warn when fclose() is used as a while loop condition

Author: francois-berder

lib/checkio.cpp

@@ -258,8 +258,16 @@ void CheckIO::checkFileUsage()
                             tmp = tmp->astParent();
                         }
                         if (loopTok) {
-                            const Token* bodyStart = loopTok->linkAt(1)->next();
-                            const Token* bodyEnd = bodyStart->link();
+                            const Token* bodyEnd = nullptr;
+                            const Token* bodyStart = nullptr;
+
+                            if (Token::simpleMatch(loopTok->previous(), "}")) {  // Handle do-while loops
+                                bodyEnd = loopTok->previous();
+                                bodyStart = bodyEnd->link();
+                            } else {
+                                bodyStart = loopTok->linkAt(1)->next();
+                                bodyEnd = bodyStart->link();
+                            }
 
                             // Do not trigger a warning if the loop always exits or if the file is opened again in the loop.
                             if (!isReturnScope(bodyEnd, mSettings->library) && Token::findmatch(bodyStart, "%var% = fopen|freopen", bodyEnd, fileTok->varId()) == nullptr)

test/testio.cpp

@@ -562,6 +562,12 @@ class TestIO : public TestFixture {
               "}");
         ASSERT_EQUALS("", errout_str());
 
+        check("void foo() {\n"
+              "    FILE *a = fopen(\"aa\", \"r\");\n"
+              "    do {} while (fclose(a));\n"
+              "}");
+        ASSERT_EQUALS("[test.cpp:3:18]: (error) Used file that is not opened. [useClosedFile]\n", errout_str());
+
         // #6823
         check("void foo() {\n"
               "    FILE f[2];\n"