Work around MinGW-make's magic prefixing of paths.

When building QNX on MS-Windows, make magically adds the Msys root as
prefix to variables whose values look like paths; this applies to both
environment variables and variables given values on the command-line.
When we don't actually want to install under the Msys root, this is
unwelcome "help".  So (for MinGW's make) support a magic prefix of our
own, @msyshack@, that'll make a path value for INSTALL_ROOT not look
like a path to make; we can then strip it off when we come to use it.

Change-Id: I951ad3c8fe3e5cfb49e6e361d7fff779f3a9d716
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@theqtcompany.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@theqtcompany.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/qmake/generators/win32/mingw_make.cpp b/qmake/generators/win32/mingw_make.cpp
index 97bfef88a4..1837c6c0cf 100644
--- a/qmake/generators/win32/mingw_make.cpp
+++ b/qmake/generators/win32/mingw_make.cpp
@@ -112,6 +112,18 @@ bool MingwMakefileGenerator::writeMakefile(QTextStream &t)
     return false;
  }
 
+QString MingwMakefileGenerator::installRoot() const
+{
+    /*
+      We include a magic prefix on the path to bypass mingw-make's "helpful"
+      intervention in the environment, recognising variables that look like
+      paths and adding the msys system root as prefix, which we don't want.
+      Once this hack has smuggled INSTALL_ROOT into make's variable space, we
+      can trivially strip the magic prefix back off to get the path we meant.
+     */
+    return QStringLiteral("$(INSTALL_ROOT:@msyshack@%=%)");
+}
+
 void createLdObjectScriptFile(const QString &fileName, const ProStringList &objList)
 {
     QString filePath = Option::output_dir + QDir::separator() + fileName;