Fix #15107: Exporting XML via GUI escapes special characters twice. - #8943

AI review

The writer no longer escapes twice, but the reader still unescapes twice. XmlReportV2::writeError() now relies on QXmlStreamWriter's escaping alone. XmlReportV2::readError() still runs XmlReport::unquoteMessage() on msg, verbose, file, file0 and info after QXmlStreamReader has already decoded them. Any text that contains a literal entity such as <, &, " or ' therefore changes on a save/load round trip. Before this PR the round trip kept the text intact, because the extra quoting and unquoting cancelled out.

Cppcheck produces such messages itself. if (strcmp(s, "<") == 0 && strcmp(s, "<") == 0) gives Condition 'strcmp(s,"<")==0' is always true. After saving this from the GUI (or after it is written to the project's lastResults.xml) and loading it again, the message reads strcmp(s,"<"). ErrorItem::same() compares message and errorPath when there is no hash, so these items can also lose their sinceDate and tags in updateFromOldReport.

To keep reading old double-escaped files, the unquoting should depend on the file, for example on a version or marker in the header that this PR's writer emits. It should not run on every file. The new test does not catch the problem because its strings contain no literal entity. The XML that the CLI writes was already decoded twice by the GUI before this PR; this PR adds the same problem for files the GUI writes itself.

Testing

• Qt is not installed in the container, so I could not build the GUI or run gui/test/xmlreportv2. The problem is found by reading the code, but it is concrete.
• Built cppcheck and testrunner in pr/ with make -j8; ./testrunner TestErrorLogger passes. The PR does not change the core library or the CLI.
• Showed that cppcheck emits messages with literal entities:

// scratch/a.c
#include <string.h>
void f(const char *s) {
    if (strcmp(s, "&lt;") == 0 && strcmp(s, "&lt;") == 0) {}
}

$ pr/cppcheck --enable=all --xml a.c
<error id="knownConditionTrueFalse" ... msg="Condition &apos;strcmp(s,&quot;&amp;lt;&quot;)==0&apos; is always true" ...>
    <location file="a.c" line="3" column="53" info="Condition &apos;strcmp(s,&quot;&amp;lt;&quot;)==0&apos; is always true"/>

• Round trip in the GUI, traced in the code. The message is Condition 'strcmp(s,"<")==0' is always true.
  • With the PR, the writer stores <. QXmlStreamReader decodes that to <, and unquoteMessage then turns it into <, so the reloaded message has strcmp(s,"<").
  • On base, the writer stored <. Reading decoded it to < and unquoting gave <, so the message came back correctly.
• A version of the new test that would catch this: set item.summary = "x < y", then check QCOMPARE(errors[0].summary, item.summary) after reading.

Automated review of 54b2dde by Claude. The pull request was built and tested locally.

AI review

I found no new problems. The earlier review said the reader still unescaped a second time. That is fixed in this version: readError() no longer calls unquoteMessage, and both functions are removed. A grep finds no other callers. Text that contains a literal entity such as < now comes back unchanged after a save and reload. This includes the XML that the CLI writes, which the GUI used to decode twice. Old results files written by the GUI will now show the extra escaping, and items without a hash may stop matching in updateFromOldReport. The author has said this break with old files is intended (comments.md), so I don't report it again. The stubs removed from testresultstree.cpp are no longer needed, because nothing refers to the removed functions any more.

Testing

• GUI not built or tested: Qt is not installed in the container, so I could not build the GUI or run gui/test/xmlreportv2. My conclusions about the GUI code come from reading it.
• CLI: built cppcheck in pr/ with make -j8 cppcheck; the build succeeded.
• Round trip: checked with CLI output that contains a literal entity:

  // scratch/a.c
  #include <string.h>
  void f(const char *s) {
      if (strcmp(s, "&lt;") == 0 && strcmp(s, "&lt;") == 0) {}
  }

  pr/cppcheck --enable=all --xml a.c writes msg="Condition 'strcmp(s,"<")==0' is always true".
  • I read this attribute with a standard XML parser, without the extra unquoting, the way the PR's readError() does now. Then I wrote it out and read it again, the way writeError() and readError() do (python3 -I rt.py r.xml).
  • Both times the message was Condition 'strcmp(s,"<")==0' is always true, so it came back intact.
  • Before the PR, the GUI's unquoteMessage would have turned it into strcmp(s,"<").
• Leftover calls: grep -rn quoteMessage over the PR tree finds nothing.

Automated review of f968345 by Claude. The pull request was built and tested locally.