fix QMAKE_DEFAULT_*DIRS resolution with apple SDK, take 2

the code got factored out to an own toolchain.prf file, which is
load()ed from default_pre.prf, so no change at first.
however, on mac, we shadow toolchain.prf, and make it load() sdk.prf
first.

a side effect, it has become harder to disable the use of an sdk
altogether: putting CONFIG-=sdk into a project file or the qmake
command line has no effect now. instead, it's possible to put it into
.qmake.{conf,cache}.
to make it simpler again, it's conceivable to finally add qmake -pre,
which would allow setting variables before default_pre.prf is executed.

take 2: there was nothing wrong with the original patch, but in 5.8,
CONFIG+=simulator_and_device moved from qconfig.pri to various prf files
that would do it according to the simulator_and_device configure
feature, which would be way too late for the "pulled ahead" sdk.prf
loading. as simulator_and_device is now gone entirely, it is safe to
re-apply this patch (mostly) as-is.

Task-number: QTBUG-56144
Change-Id: I6cf484982eaed8af39f7a539c60f5a087a299914
Reviewed-by: Jake Petroules <jake.petroules@qt.io>

1 files changed, 47 insertions, 0 deletions

diff --git a/mkspecs/features/toolchain.prf b/mkspecs/features/toolchain.prf
new file mode 100644
index 0000000000..70547a3cdf
--- /dev/null
+++ b/mkspecs/features/toolchain.prf
@@ -0,0 +1,47 @@
+
+isEmpty(QMAKE_DEFAULT_INCDIRS):!host_build {
+    #
+    # Get default include and library paths from compiler
+    #
+    gcc {
+        !equals(QMAKE_HOST.os, Windows) {
+            cmd_prefix = "LC_ALL=C"
+            cmd_suffix = "</dev/null >/dev/null"
+        } else {
+            cmd_prefix = "set LC_ALL=C&"
+            cmd_suffix = "<NUL >NUL"
+        }
+        output = $$system("$$cmd_prefix $$QMAKE_CXX $$QMAKE_CXXFLAGS -xc++ -E -v - 2>&1 $$cmd_suffix", lines)
+        add_includes = false
+        for (line, output) {
+            line ~= s/^ *//  # remove leading spaces
+            contains(line, "LIBRARY_PATH=.*") {
+                line ~= s/^LIBRARY_PATH=//  # remove leading LIBRARY_PATH=
+                paths = $$split(line, $$QMAKE_DIRLIST_SEP)
+                for (path, paths): \
+                    QMAKE_DEFAULT_LIBDIRS += $$clean_path($$path)
+            } else: contains(line, "$${LITERAL_HASH}include <.*") {  # #include <...> search starts here:
+                add_includes = true
+            } else: contains(line, "End of search.*") {
+                add_includes = false
+            } else: $$add_includes {
+                !contains(line, ".* \\(framework directory\\)"): \
+                    QMAKE_DEFAULT_INCDIRS += $$clean_path($$line)
+            }
+        }
+        QMAKE_DEFAULT_LIBDIRS = $$unique(QMAKE_DEFAULT_LIBDIRS)
+    } else: msvc {
+        LIB = $$getenv("LIB")
+        QMAKE_DEFAULT_LIBDIRS = $$split(LIB, $$QMAKE_DIRLIST_SEP)
+        INCLUDE = $$getenv("INCLUDE")
+        QMAKE_DEFAULT_INCDIRS = $$split(INCLUDE, $$QMAKE_DIRLIST_SEP)
+    }
+
+    unix {
+        isEmpty(QMAKE_DEFAULT_INCDIRS): QMAKE_DEFAULT_INCDIRS = /usr/include /usr/local/include
+        isEmpty(QMAKE_DEFAULT_LIBDIRS): QMAKE_DEFAULT_LIBDIRS = /lib /usr/lib
+    }
+
+    !isEmpty(QMAKE_DEFAULT_INCDIRS): cache(QMAKE_DEFAULT_INCDIRS, set stash)
+    !isEmpty(QMAKE_DEFAULT_LIBDIRS): cache(QMAKE_DEFAULT_LIBDIRS, set stash)
+}