Pick up default library paths for clang

We need to actually run the linker, otherwise clang will just
run the preprocessing step as we asked for. We build as a shared
library to not have to provide a main() function.

Change-Id: Ied34757bb5c43a862bf2d9778340c497b93d572f
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>

1 files changed, 19 insertions, 2 deletions

diff --git a/mkspecs/features/toolchain.prf b/mkspecs/features/toolchain.prf
index 46a9c5707a..d3487ef1ab 100644
--- a/mkspecs/features/toolchain.prf
+++ b/mkspecs/features/toolchain.prf
@@ -40,19 +40,36 @@ isEmpty($${target_prefix}.INCDIRS) {
         # QMAKE_DEFAULT_*DIRS, because they're handled in a single build pass.
         darwin: cxx_flags += -isysroot $$QMAKE_MAC_SDK_PATH
 
-        output = $$system("$$cmd_prefix $$QMAKE_CXX $$qtMakeExpand($$cxx_flags) -xc++ -E -v - 2>&1 $$cmd_suffix", lines)
+        clang: \
+            # Need to link to pick up library paths
+            cxx_flags += $$QMAKE_LFLAGS_SHLIB -o /dev/null -v -Wl,-v
+        else: \
+            # gcc is fine with just preprocessing
+            cxx_flags += -E -v
+
+        output = $$system("$$cmd_prefix $$QMAKE_CXX $$qtMakeExpand($$cxx_flags) -xc++ - 2>&1 $$cmd_suffix", lines)
         add_includes = false
+        add_libraries = false
         for (line, output) {
-            line ~= s/^ *//  # remove leading spaces
+            line ~= s/^[ \\t]*//  # remove leading spaces
             contains(line, "LIBRARY_PATH=.*") {
                 line ~= s/^LIBRARY_PATH=//  # remove leading LIBRARY_PATH=
                 paths = $$split(line, $$QMAKE_DIRLIST_SEP)
                 for (path, paths): \
                     QMAKE_DEFAULT_LIBDIRS += $$clean_path($$path)
+            } else: contains(line, "Library search paths:") {
+                add_libraries = true
             } else: contains(line, "$${LITERAL_HASH}include <.*") {  # #include <...> search starts here:
                 add_includes = true
             } else: contains(line, "End of search.*") {
                 add_includes = false
+            } else: $$add_libraries {
+                # We assume all library search paths are absolute
+                !contains(line, "^/.*") {
+                    add_libraries = false
+                    next()
+                }
+                QMAKE_DEFAULT_LIBDIRS += $$clean_path($$line)
             } else: $$add_includes {
                 !contains(line, ".* \\(framework directory\\)"): \
                     QMAKE_DEFAULT_INCDIRS += $$clean_path($$line)