Fix "qmake -spec foo" call for cross builds

In a cross built Qt, for example Qt for Android, calling "qmake -spec
android-clang" led to an error message:
    "Could not find qmake spec '-qtconf'."

This happened, because:
- the qmake in Qt for Android is a wrapper script that calls
  "qmake -qtconf qt_target.conf -spec android-clang"
- the first stage of command line argument handling in qmake garbled the
  call to "qmake -spec -qtconf qt_target.conf android-clang"

We do not modify the order of arguments anymore.

Instead, we skip the "-qtconf <file>" arguments in the first argument
handling stage that is supposed to determine qmake's modus
operandi (like -project or -query).

In addition, we need to fix the assignment of
QLibraryInfoPrivate::qtconfManualPath which was only done if
QMakeGlobals::addCommandLineArguments returned ArgumentsOk. However,
this function returns ArgumentUnknown, if it encounters an argument it
cannot handle - like the project name.
Now, we assign QLibraryInfoPrivate::qtconfManualPath if there was no
error detected.

Document the return values of addCommandLineArguments.

This amends commit 661b586a69740bd9a1791622f8b238d290ebe00d.

Pick-to: 6.1 6.0
Fixes: QTBUG-93079
Task-number: QTBUG-85136
Change-Id: I12ec25b17d64c00be2a3904b7c4a975b781500a0
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>

1 files changed, 7 insertions, 0 deletions

diff --git a/qmake/library/qmakeglobals.cpp b/qmake/library/qmakeglobals.cpp
index 247084f6c6..b4dab9ce8f 100644
--- a/qmake/library/qmakeglobals.cpp
+++ b/qmake/library/qmakeglobals.cpp
@@ -103,6 +103,13 @@ QString QMakeGlobals::cleanSpec(QMakeCmdLineParserState &state, const QString &s
     return ret;
 }
 
+/*
+ * Return value meanings:
+ * ArgumentUnknown    The argument at *pos was not handled by this function.
+ *                    Leave it to the caller to handle this argument.
+ * ArgumentMalformed  There was an error detected.
+ * ArgumentsOk        All arguments were known. There are no arguments left to handle.
+ */
 QMakeGlobals::ArgumentReturn QMakeGlobals::addCommandLineArguments(
         QMakeCmdLineParserState &state, QStringList &args, int *pos)
 {