fixup! fixup! fixup! Fix #958: warn when feof() is used as a while loop condition

Author: francois-berder

lib/checkio.cpp

@@ -506,9 +506,14 @@ void CheckIO::checkWrongfeofUsage()
 
     for (const Scope * scope : symbolDatabase->functionScopes) {
         for (const Token *tok = scope->bodyStart->next(); tok != scope->bodyEnd; tok = tok->next()) {
+            // TODO: Handle do-while and for loops
             if (!Token::simpleMatch(tok, "while ( ! feof ("))
                 continue;
 
+            // Bail out if we reach a do-while loop
+            if (Token::simpleMatch(tok->previous(), "}") && Token::simpleMatch(tok->linkAt(-1)->previous(), "do"))
+                continue;
+
             // Bail out if we cannot identify file pointer
             const int fpVarId = tok->tokAt(5)->varId();
             if (fpVarId == 0)

man/checkers/wrongfeofUsage.md

@@ -7,7 +7,7 @@
 
 ## Description
 
-`feof()` returns non-zero only after a read operation has failed because the end of file was reached. When used as the sole condition of a `while` loop, the loop body executes one extra time after the last successful read: the read fails silently (or returns partial data), and only then does `feof()` return true and terminate the loop.
+`feof()` returns non-zero only after a read operation has failed because the end of file was reached. When used as the sole condition of a loop, the loop body executes one extra time after the last successful read: the read fails silently (or returns partial data), and only then does `feof()` return true and terminate the loop.
 
 This checker warns when it finds feof in the loop condition and either:
 - no file-read call (e.g. `fgets`, `fread`, `fscanf`) precedes the loop and is also present inside the loop body