With the update to Qt 5.9.3, the configure script and qmake expect an mkspec
name, not an absolute path, which is why r458293 switched to using
${QMAKESPEC:T}.
However, the :T modifier breaks things when CXX is set to an absolute path
instead of just "c++", QMAKE_COMPILER is a shell string that will be evaluated
only after make invokes `configure' with CONFIGURE_ARGS. In other words, we end
up turning something like
$$(ccver="$$(/usr/bin/c++ --version)"; case "$$ccver" in *clang*) echo clang ;; *) echo g++ ;; esac)
into
/c++ --version)"; case "$$ccver" in *clang*) echo clang ;; *) echo g++ ;; esac)
which is obviously invalid.
We now just avoid being too smart and set a separate variable called
QMAKESPECNAME, which contains only the mkspec name and that we use both when
setting CONFIGURE_ARGS as well as to create QMAKESPEC.
PR: 224971
9c3d7007b2