eclipse: add generation of editor language settings

Add automatic generation of editor language settings for C and C++,
so the automatic code correction uses the correct compiler and
compiler flags, including for example the correct C/C++ standard
so construct from such standards are correctly managed by the IDE.
Correct compiler and flags are automatically generated using the
build environment data gathered during configure phase.
The playground example has been modified to contain some code that
is standard specific to demonstrate the new feature when run under
Eclipse.

playground/eclipse/c/exLibC/src/exLibC.cpp

@@ -1,9 +1,13 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <iostream>
 
 #include <pkg1/exLibC/exLibC.hpp>
 
 int check_smaller(int value) {
+	const char* foo = u8"bar";	// u8 is C++17 only
+	std::cout << __cplusplus << std::endl; // Check version of C++ standard
+
 	if (value < HELLO_LIMIT) {
 		return 0;
 	} else {

playground/eclipse/c/wscript

@@ -2,12 +2,15 @@
 # encoding: utf-8
 
 def options(opt):
-	# We are using C++
-	opt.load('compiler_cxx')
+	# We are using C and C++
+	opt.load('compiler_c compiler_cxx')
 
 def configure(conf):
-	# We are using C++
-	conf.load('compiler_cxx')
+	# We are using C and C++
+	conf.load('compiler_c compiler_cxx')
+	# Force some standards to see that IDE will follow them
+	conf.env.CXXFLAGS=['-std=c++17']
+	conf.env.CFLAGS=['-std=c17']
 
 def build(bld):
 	bld.shlib(source='exLibC/src/exLibC.cpp', includes='exLibC/src/include', target='exampleLibC', export_includes='exLibC/src/include/')

waflib/extras/eclipse.py

@@ -25,6 +25,8 @@ cdt_core = oe_cdt + '.core'
 cdt_bld = oe_cdt + '.build.core'
 extbuilder_dir = '.externalToolBuilders'
 extbuilder_name = 'Waf_Builder.launch'
+settings_dir = '.settings'
+settings_name = 'language.settings.xml'
 
 class eclipse(Build.BuildContext):
 	cmd = 'eclipse'
@@ -156,6 +158,61 @@ class eclipse(Build.BuildContext):
 			project = self.impl_create_javaproject(javasrcpath, javalibpath)
 			self.write_conf_to_xml('.classpath', project)
 
+		# Create editor language settings to have correct standards applied in IDE, as per project configuration
+		try:
+			os.mkdir(settings_dir)
+		except OSError:
+			pass	# Ignore if dir already exists
+
+		lang_settings = Document()
+		project = lang_settings.createElement('project')
+
+		# Language configurations for C and C++ via cdt
+		if hasc:
+			configuration = self.add(lang_settings, project, 'configuration',
+							{'id' : 'org.eclipse.cdt.core.default.config.1', 'name': 'Default'})
+
+			extension = self.add(lang_settings, configuration, 'extension', {'point': 'org.eclipse.cdt.core.LanguageSettingsProvider'})
+
+			provider = self.add(lang_settings, extension, 'provider',
+							{ 'copy-of': 'extension',
+							  'id': 'org.eclipse.cdt.ui.UserLanguageSettingsProvider'})
+
+			provider = self.add(lang_settings, extension, 'provider-reference',
+							{ 'id': 'org.eclipse.cdt.core.ReferencedProjectsLanguageSettingsProvider',
+							  'ref': 'shared-provider'})
+
+			provider = self.add(lang_settings, extension, 'provider-reference',
+							{ 'id': 'org.eclipse.cdt.managedbuilder.core.MBSLanguageSettingsProvider',
+							  'ref': 'shared-provider'})
+
+			# C and C++ are kept as separated providers so appropriate flags are used also in mixed projects
+			if self.env.CC:
+				provider = self.add(lang_settings, extension, 'provider',
+							{ 'class': 'org.eclipse.cdt.managedbuilder.language.settings.providers.GCCBuiltinSpecsDetector',
+							  'console': 'false',
+							  'id': 'org.eclipse.cdt.managedbuilder.language.settings.providers.GCCBuiltinSpecsDetector.1',
+							  'keep-relative-paths' : 'false',
+							  'name': 'CDT GCC Built-in Compiler Settings',
+							  'parameter': '%s %s ${FLAGS} -E -P -v -dD "${INPUTS}"'%(self.env.CC[0],' '.join(self.env['CFLAGS'])),
+							  'prefer-non-shared': 'true' })
+
+				self.add(lang_settings, provider, 'language-scope', { 'id': 'org.eclipse.cdt.core.gcc'})
+
+			if self.env.CXX:
+				provider = self.add(lang_settings, extension, 'provider',
+							{ 'class': 'org.eclipse.cdt.managedbuilder.language.settings.providers.GCCBuiltinSpecsDetector',
+							  'console': 'false',
+							  'id': 'org.eclipse.cdt.managedbuilder.language.settings.providers.GCCBuiltinSpecsDetector.2',
+							  'keep-relative-paths' : 'false',
+							  'name': 'CDT GCC Built-in Compiler Settings',
+							  'parameter': '%s %s ${FLAGS} -E -P -v -dD "${INPUTS}"'%(self.env.CXX[0],' '.join(self.env['CXXFLAGS'])),
+							  'prefer-non-shared': 'true' })
+				self.add(lang_settings, provider, 'language-scope', { 'id': 'org.eclipse.cdt.core.g++'})
+
+		lang_settings.appendChild(project)
+		self.write_conf_to_xml('%s%s%s'%(settings_dir, os.path.sep, settings_name), lang_settings)
+
 	def impl_create_project(self, executable, appname, hasc, hasjava, haspython, waf_executable):
 		doc = Document()
 		projectDescription = doc.createElement('projectDescription')
@@ -348,6 +405,12 @@ class eclipse(Build.BuildContext):
 
 		self.add(doc, storageModule, 'project', {'id': '%s.null.1'%appname, 'name': appname})
 
+		storageModule = self.add(doc, cproject, 'storageModule',
+							{'moduleId': 'org.eclipse.cdt.core.LanguageSettingsProviders'})
+
+		storageModule = self.add(doc, cproject, 'storageModule',
+							{'moduleId': 'scannerConfiguration'})
+
 		doc.appendChild(cproject)
 		return doc