Fix compilation of PCRE2 under Intel CET

Ubuntu 20.04 enables -fcf-protection by default.

PCRE2 10.35 sees this but complains that -mshstk is also necessary
to build its JIT. Detect whether the compiler is enabling Intel CET
automatically, and if so, build PCRE2 with the right options.

Pick-to: 5.15
Change-Id: I3440e689b81f4f07055f211a4fa7331a43eb410d
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

configure.json

@@ -635,6 +635,17 @@
             "label": "ccache",
             "type": "files",
             "files": [ "ccache" ]
+        },
+        "intelcet": {
+            "label": "Support for Intel Control-flow Enforcement Technology",
+            "type": "compile",
+            "test": {
+                "main": [
+                    "#if !defined(__CET__)",
+                    "#  error Intel CET not available",
+                    "#endif"
+                ]
+            }
         }
     },
 
@@ -1401,6 +1412,11 @@
             "autoDetect": "features.shared",
             "condition": "features.dlopen || config.win32 || !features.shared",
             "output": [ "privateFeature" ]
+        },
+        "intelcet": {
+            "label": "Using Intel CET",
+            "condition": "tests.intelcet",
+            "output": [ "privateFeature" ]
         }
     },
 

mkspecs/common/gcc-base.conf

@@ -54,6 +54,7 @@ QMAKE_CFLAGS_SPLIT_SECTIONS += -ffunction-sections -fdata-sections
 QMAKE_CFLAGS_LTCG           = -flto -fno-fat-lto-objects
 QMAKE_CFLAGS_LTCG_FATOBJECTS = -ffat-lto-objects
 QMAKE_CFLAGS_DISABLE_LTCG   = -fno-lto
+QMAKE_CFLAGS_SHSTK          = -mshstk
 
 QMAKE_CXXFLAGS            += $$QMAKE_CFLAGS
 QMAKE_CXXFLAGS_DEPS       += $$QMAKE_CFLAGS_DEPS
@@ -74,6 +75,7 @@ QMAKE_CXXFLAGS_SPLIT_SECTIONS += $$QMAKE_CFLAGS_SPLIT_SECTIONS
 QMAKE_CXXFLAGS_LTCG        = $$QMAKE_CFLAGS_LTCG
 QMAKE_CXXFLAGS_LTCG_FATOBJECTS = $$QMAKE_CFLAGS_LTCG_FATOBJECTS
 QMAKE_CXXFLAGS_DISABLE_LTCG   = $$QMAKE_CFLAGS_DISABLE_LTCG
+QMAKE_CXXFLAGS_SHSTK       = $$QMAKE_CFLAGS_SHSTK
 
 QMAKE_LFLAGS           +=
 QMAKE_LFLAGS_DEBUG     +=

src/3rdparty/pcre2/pcre2.pri

@@ -5,6 +5,11 @@ win32: MODULE_DEFINES += PCRE2_STATIC
 
 DEFINES += HAVE_CONFIG_H
 
+qtConfig(intelcet) {
+    QMAKE_CFLAGS += QMAKE_CFLAGS_SHSTK
+    QMAKE_CXXFLAGS += QMAKE_CXXFLAGS_SHSTK
+}
+
 SOURCES += \
     $$PWD/src/pcre2_auto_possess.c \
     $$PWD/src/pcre2_chartables.c \