Implement a more direct headersclean check

Test each include file directly, instead of doing a large #include. This
verifies that each header is compilable on its own. One big advantage of
doing it via a special compiler in qmake is that we skip pre-compiled
headers, which has hidden build errors in the past.

This solution is implemented by making syncqt produce a second list of
headers.  This list is the same as the list of headers in the source
code to be installed, minus the headers that declare themselves to be
unclean, via the pragma:
  #pragma qt_sync_skip_header_check

This mechanism is applied only for public libraries (skipping
QtPlatformSupport, an internal_module).

This test is enabled only for -developer-builds of Qt because it
increases the compilation time.

On QtTest: the library only links to QtCore, but it has two headers that
provide inline-only functionality by including QtGui and QtWidgets
headers (namely, qtest_gui.h and qtest_widget.h). If those two modules
aren't getting compiled due to -no-gui or -no-widgets to configure, we
need to remove the respective headers from the list of headers to be
checked. If they are being built, then we need to make QtTest's build
wait for the headers to be generated and that happens when qmake is
first run inside the src/gui and src/widgets directories.

Change-Id: I57d64bd697a92367c8464c073a42e4d142a9a15f
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>

8 files changed, 138 insertions, 12 deletions

diff --git a/bin/syncqt.pl b/bin/syncqt.pl
index 3bee0175ff..3b3e127e86 100755
--- a/bin/syncqt.pl
+++ b/bin/syncqt.pl
@@ -190,8 +190,9 @@ sub shouldMasterInclude {
 }
 
 ######################################################################
-# Syntax:  classNames(iheader)
+# Syntax:  classNames(iheader, clean)
 # Params:  iheader, string, filename to parse for classname "symlinks"
+#          (out) clean, boolean, will be set to false if the header isn't clean
 #
 # Purpose: Scans through iheader to find all classnames that should be
 #          synced into library's include structure.
@@ -199,7 +200,8 @@ sub shouldMasterInclude {
 ######################################################################
 sub classNames {
     my @ret;
-    my ($iheader) = @_;
+    my ($iheader, $clean) = @_;
+    $$clean = 1;
 
     my $ihdrbase = basename($iheader);
     my $classname = $classnames{$ihdrbase};
@@ -212,6 +214,7 @@ sub classNames {
             chomp $line;
                         chop $line if ($line =~ /\r$/);
             if($line =~ /^\#/) {
+                $$clean = 0 if ($line =~ m/^#pragma qt_sync_skip_header_check/);
                 return @ret if($line =~ m/^#pragma qt_sync_stop_processing/);
                 push(@ret, $1) if($line =~ m/^#pragma qt_class\(([^)]*)\)[\r\n]*$/);
                 $line = 0;
@@ -828,6 +831,7 @@ foreach my $lib (@modules_to_sync) {
     my $pri_install_pfiles = "";
     my $pri_install_qpafiles = "";
     my $pri_injections = "";
+    my $pri_clean_files = "";
 
     my $libcapitals = uc($lib);
     my $master_contents =
@@ -929,9 +933,10 @@ foreach my $lib (@modules_to_sync) {
                             }
                         }
 
+                        my $clean_header;
                         my $iheader = $subdir . "/" . $header;
                         $iheader =~ s/^\Q$basedir\E/$out_basedir/ if ($shadow);
-                        my @classes = $public_header && (!$minimal && $is_qt) ? classNames($iheader) : ();
+                        my @classes = $public_header && (!$minimal && $is_qt) ? classNames($iheader, \$clean_header) : ();
                         if($showonly) {
                             print "$header [$lib]\n";
                             foreach(@classes) {
@@ -980,6 +985,7 @@ foreach my $lib (@modules_to_sync) {
                                     $injection .= ":$class";
                                 }
                                 $pri_install_files.= "$pri_install_iheader ";;
+                                $pri_clean_files .= "$pri_install_iheader " if ($clean_header);
                             }
                             elsif ($qpa_header) {
                                 $pri_install_qpafiles.= "$pri_install_iheader ";;
@@ -1120,6 +1126,7 @@ foreach my $lib (@modules_to_sync) {
         $headers_pri_contents .= "SYNCQT.HEADER_CLASSES = $pri_install_classes\n";
         $headers_pri_contents .= "SYNCQT.PRIVATE_HEADER_FILES = $pri_install_pfiles\n";
         $headers_pri_contents .= "SYNCQT.QPA_HEADER_FILES = $pri_install_qpafiles\n";
+        $headers_pri_contents .= "SYNCQT.CLEAN_HEADER_FILES = $pri_clean_files\n";
         $headers_pri_contents .= "SYNCQT.INJECTIONS = $pri_injections\n";
         my $headers_pri_file = "$out_basedir/include/$lib/headers.pri";
         writeFile($headers_pri_file, $headers_pri_contents, $lib, "headers.pri file");
diff --git a/configure b/configure
index 4addf22896..03421dfc4c 100755
--- a/configure
+++ b/configure
@@ -762,6 +762,7 @@ QPA_PLATFORM_GUARD=yes
 CFG_CXX11=auto
 CFG_DIRECTWRITE=no
 CFG_WERROR=auto
+CFG_HEADERSCLEAN=auto
 CFG_QREAL=double
 OPT_MAC_SDK=
 COMMERCIAL_USER=ask
@@ -2240,6 +2241,13 @@ while [ "$#" -gt 0 ]; do
             UNKNOWN_OPT=yes
         fi
         ;;
+    headersclean)
+        if [ "$VAL" = "yes" ] || [ "$VAL" = "no" ]; then
+            CFG_HEADERSCLEAN="$VAL"
+        else
+            UNKNOWN_OPT=yes
+        fi
+        ;;
     xkb-config-root)
         CFG_XKB_CONFIG_ROOT="$VAL"
         ;;
@@ -6712,8 +6720,16 @@ if [ "$CFG_DEV" = "yes" ]; then
     if [ "$CFG_WERROR" != "no" ]; then
         QMAKE_CONFIG="$QMAKE_CONFIG warnings_are_errors"
     fi
-elif [ "$CFG_WERROR" = "yes" ]; then
-    QMAKE_CONFIG="$QMAKE_CONFIG warnings_are_errors"
+    if [ "$CFG_HEADERSCLEAN" != "no" ]; then
+        QMAKE_CONFIG="$QMAKE_CONFIG headersclean"
+    fi
+else
+    if [ "$CFG_WERROR" = "yes" ]; then
+        QMAKE_CONFIG="$QMAKE_CONFIG warnings_are_errors"
+    fi
+    if [ "$CFG_HEADERSCLEAN" = "yes" ]; then
+        QMAKE_CONFIG="$QMAKE_CONFIG headersclean"
+    fi
 fi
 
 cat >>"$QTCONFIG.tmp" <<EOF
diff --git a/mkspecs/features/data/dummy.cpp b/mkspecs/features/data/dummy.cpp
new file mode 100644
index 0000000000..6bda7320e9
--- /dev/null
+++ b/mkspecs/features/data/dummy.cpp
@@ -0,0 +1,2 @@
+// Used when we need to compile with no source code
+// (controls are in the command-line)
diff --git a/mkspecs/features/qt_module.prf b/mkspecs/features/qt_module.prf
index b85dbfb9c3..7ed5ea0561 100644
--- a/mkspecs/features/qt_module.prf
+++ b/mkspecs/features/qt_module.prf
@@ -60,10 +60,6 @@ MODULE_DEFINES = $$MODULE_DEFINE $$MODULE_DEFINES
 
 load(qt_module_pris)
 
-INCLUDEPATH *= $$eval(QT.$${MODULE}.includes) $$eval(QT.$${MODULE}_private.includes)
-
-!no_module_headers: load(qt_module_headers)
-
 #other
 TEMPLATE         = lib
 DESTDIR          = $$eval(QT.$${MODULE_ID}.libs)
@@ -73,6 +69,11 @@ CONFIG          += qmake_cache target_qt
 
 QMAKE_DOCS_TARGETDIR = qt$${MODULE}
 
+load(qt_common)
+
+!no_module_headers: load(qt_module_headers)
+INCLUDEPATH *= $$eval(QT.$${MODULE}.includes) $$eval(QT.$${MODULE}_private.includes)
+
 # If Qt was configured with -debug-and-release then build the module the same way
 # - unless this is a host library
 !host_build:if(win32|mac):!macx-xcode {
@@ -175,7 +176,6 @@ android: CONFIG += qt_android_deps
 load(qt_installs)
 
 load(qt_targets)
-load(qt_common)
 
 # this builds on top of qt_common
 unix|mingw {
diff --git a/mkspecs/features/qt_module_headers.prf b/mkspecs/features/qt_module_headers.prf
index fc3ec75e82..ed76e67baa 100644
--- a/mkspecs/features/qt_module_headers.prf
+++ b/mkspecs/features/qt_module_headers.prf
@@ -76,3 +76,89 @@ SYNCQT.HEADER_FILES += $$MODULE_MASTER_DEPS_HEADER
 }
 
 CONFIG += qt_install_headers
+
+headersclean:!internal_module {
+    # Make sure that the header compiles with our strict options
+    hcleanDEFS = -DQT_NO_CAST_TO_ASCII=1 \
+                 -DQT_NO_CAST_FROM_ASCII=1 \
+                 -DQT_STRICT_ITERATORS \
+                 -DQT_NO_URL_CAST_FROM_STRING=1 \
+                 -DQT_NO_CAST_FROM_BYTEARRAY=1 \
+                 -DQT_NO_KEYWORDS=1 \
+                 -DQT_USE_FAST_CONCATENATION \
+                 -DQT_USE_FAST_OPERATOR_PLUS \
+                 -Dsignals=int \
+                 -Dslots=int \
+                 -Demit=public: \
+                 -Dforeach=public: \
+                 -Dforever=public:
+
+    gcc {
+        # Turn on some extra warnings not found in -Wall -Wextra.
+        # Common to GCC, Clang and ICC (and other compilers that masquerade as GCC):
+        hcleanFLAGS = -Wall -Wextra -Werror \
+                      -Woverloaded-virtual -Wshadow -Wundef \
+                      -Wnon-virtual-dtor -Wpointer-arith -Wformat-security \
+                      -Wno-long-long -Wno-variadic-macros -pedantic-errors
+
+        intel_icc {
+            # these warnings are disabled because explicit constructors with zero or
+            # multiple arguments are permitted in C++11:
+            # 2304: non-explicit constructor with single argument may cause implicit type conversion
+            # 2305: declaration of 'explicit' constructor without a single argument is redundant
+            hcleanFLAGS += -wd2304,2305
+            greaterThan(QT_ICC_MAJOR_VERSION, 13) {
+                # ICC 14+ has a bug with -Wshadow, emitting it for cases where there's no shadowing
+                # (issue ID 0000698329, task DPD200245740)
+                hcleanFLAGS -= -Wshadow
+            }
+        } else {
+            hcleanFLAGS += -Wchar-subscripts
+
+            !contains(QT_ARCH, arm):!contains(QT_ARCH, mips): \
+                hcleanFLAGS += -Wcast-align
+        }
+
+        # Use strict mode C++11 or C++98, with no GNU extensions (see -pedantic-errors above).
+        # The module might set CONFIG += c++11, but it might also change QMAKE_CXXFLAGS_CXX11
+        # or the module (or the mkspec) can set the C++11 flag on QMAKE_CXXFLAGS
+        # (or QMAKE_CXXFLAGS_{RELEASE,DEBUG} but that's unlikely).
+        c++11:contains(QMAKE_CXXFLAGS_CXX11, -std=gnu++11) {
+            hcleanFLAGS += -std=c++11
+        } else: contains(QMAKE_CXXFLAGS, -std=gnu++11) {
+            hcleanFLAGS += -std=c++11
+        } else: c++11:contains(QMAKE_CXXFLAGS_CXX11, -std=gnu++0x) {
+            hcleanFLAGS += -std=c++0x
+        } else: contains(QMAKE_CXXFLAGS, -std=gnu++0x) {
+            hcleanFLAGS += -std=c++0x
+        } else: !c++11:!contains(QMAKE_CXXFLAGS, -std=c++0x):!contains(QMAKE_CXXFLAGS, -std=c++11) {
+            hcleanFLAGS += -std=c++98
+        }
+
+        hcleanCOMMAND = $$QMAKE_CXX -c $(CXXFLAGS) $$hcleanFLAGS $(INCPATH) $$hcleanDEFS -xc++ ${QMAKE_FILE_IN} -o ${QMAKE_FILE_OUT}
+    } else: win32-msvc2013 {
+        # 4180: qualifier applied to function type has no meaning; ignored
+        # 4458: declaration of 'identifier' hides class member
+        # -Za enables strict standards behavior, but we can't add it because
+        # <windows.h> and <GL.h> violate the standards.
+        hcleanFLAGS = -WX -W3 -wd4180 -wd4458
+        hcleanCOMMAND = $$QMAKE_CXX -c $(CXXFLAGS) $$hcleanFLAGS $(INCPATH) $$hcleanDEFS -FI${QMAKE_FILE_IN} -Fo${QMAKE_FILE_OUT} \
+                        $$[QT_INSTALL_DATA/src]/mkspecs/features/data/dummy.cpp
+    }
+
+    !isEmpty(hcleanCOMMAND):if(!contains(QT_CONFIG, debug_and_release)|CONFIG(release, debug|release)) {
+        header_check.dependency_type = TYPE_C
+        header_check.CONFIG += no_link
+        header_check.output = ${QMAKE_VAR_OBJECTS_DIR}header_${QMAKE_FILE_BASE}$${first(QMAKE_EXT_OBJ)}
+        header_check.input = SYNCQT.CLEAN_HEADER_FILES
+        header_check.variable_out = PRE_TARGETDEPS
+        header_check.name = headercheck ${QMAKE_FILE_IN}
+        header_check.commands = $$hcleanCOMMAND
+        silent:header_check.commands = @echo compiling[header] ${QMAKE_FILE_IN} && $$hcleanCOMMAND
+        QMAKE_EXTRA_COMPILERS += header_check
+        SYNCQT.CLEAN_HEADER_FILES -= $$HEADERSCLEAN_EXCLUDE
+    }
+    unset(hcleanCOMMAND)
+    unset(hcleanFLAGS)
+    unset(hcleanDEFS)
+}
diff --git a/src/src.pro b/src/src.pro
index fcdc6c32e0..b4d62aa8b0 100644
--- a/src/src.pro
+++ b/src/src.pro
@@ -81,7 +81,7 @@ src_network.depends = src_corelib
 
 src_testlib.subdir = $$PWD/testlib
 src_testlib.target = sub-testlib
-src_testlib.depends = src_corelib   # src_gui & src_widgets are not build-depends
+src_testlib.depends = src_corelib   # testlib links only to corelib, but see below for the headers
 
 src_3rdparty_pcre.subdir = $$PWD/3rdparty/pcre
 src_3rdparty_pcre.target = sub-3rdparty-pcre
@@ -166,10 +166,12 @@ contains(QT_CONFIG, concurrent):SUBDIRS += src_concurrent
     SUBDIRS += src_gui src_platformsupport src_platformheaders
     contains(QT_CONFIG, opengl(es2)?):SUBDIRS += src_openglextensions
     src_plugins.depends += src_gui src_platformsupport src_platformheaders
+    src_testlib.depends += src_gui      # if QtGui is enabled, QtTest requires QtGui's headers
     !contains(QT_CONFIG, no-widgets) {
         SUBDIRS += src_tools_uic src_widgets
         TOOLS += src_tools_uic
         src_plugins.depends += src_widgets
+        src_testlib.depends += src_widgets        # if QtWidgets is enabled, QtTest requires QtWidgets's headers
         contains(QT_CONFIG, opengl(es2)?) {
             SUBDIRS += src_opengl
             src_plugins.depends += src_opengl
diff --git a/src/testlib/testlib.pro b/src/testlib/testlib.pro
index 841d913105..83f217dde9 100644
--- a/src/testlib/testlib.pro
+++ b/src/testlib/testlib.pro
@@ -97,4 +97,9 @@ mac {
     }
 }
 
+# Exclude these headers from the clean check if their dependencies aren't
+# being built
+contains(QT_CONFIG, no-widgets): HEADERSCLEAN_EXCLUDE += qtest_widgets.h
+contains(QT_CONFIG, no-gui):     HEADERSCLEAN_EXCLUDE += qtest_gui.h
+
 load(qt_module)
diff --git a/tools/configure/configureapp.cpp b/tools/configure/configureapp.cpp
index 04909525d1..c0e98507c7 100644
--- a/tools/configure/configureapp.cpp
+++ b/tools/configure/configureapp.cpp
@@ -1,7 +1,7 @@
 /****************************************************************************
 **
 ** Copyright (C) 2015 The Qt Company Ltd.
-** Copyright (C) 2013 Intel Corporation
+** Copyright (C) 2014 Intel Corporation
 ** Contact: http://www.qt.io/licensing/
 **
 ** This file is part of the tools applications of the Qt Toolkit.
@@ -927,6 +927,10 @@ void Configure::parseCmdLine()
             dictionary[ "WERROR" ] = "yes";
         } else if (configCmdLine.at(i) == "-no-warnings-are-errors") {
             dictionary[ "WERROR" ] = "no";
+        } else if (configCmdLine.at(i) == "-no-headersclean") {
+            dictionary[ "HEADERSCLEAN" ] = "no";
+        } else if (configCmdLine.at(i) == "-headersclean") {
+            dictionary[ "HEADERSCLEAN" ] = "yes";
         } else if (configCmdLine.at(i) == "-no-eventfd") {
             dictionary[ "QT_EVENTFD" ] = "no";
         } else if (configCmdLine.at(i) == "-eventfd") {
@@ -1459,9 +1463,13 @@ void Configure::parseCmdLine()
         qtConfig << "private_tests";
         if (dictionary["WERROR"] != "no")
             qmakeConfig << "warnings_are_errors";
+        if (dictionary["HEADERSCLEAN"] != "no")
+            qmakeConfig << "headersclean";
     } else {
         if (dictionary["WERROR"] == "yes")
             qmakeConfig << "warnings_are_errors";
+        if (dictionary["HEADERSCLEAN"] == "yes")
+            qmakeConfig << "headersclean";
     }
 
     if (dictionary["FORCE_ASSERTS"] == "yes")