Improve project naming and build configuration in genvslite projects

This change fixes two usability issues with the genvslite project
generation. Unlike when using the full VS backend, under genvslite the
ProjectName property wasn't being set for generated projects. This means
projects end up being named according to the project files, which
includes suffixes like "@exe" in the solution, which is undesirable.
This change adds the ProjectName field in for genvslite projects, to
keep the naming consistent with projects under the VS backend.

Additionally, previously under genvslite, no projects were set to build
under any solution configuration by default. This is inconvenient, as
the user has to manually edit the build settings for each solution
configuration before they can compile at the solution level. There was a
note in the code to do something about this. This change enables
compilation at the solution level for the default startup project in the
solution, so the user can now just press F5 to build the solution and
run the default startup project, as they would typically expect.

mesonbuild/backend/vs2010backend.py

@@ -480,7 +480,7 @@ class Vs2010Backend(backends.Backend):
                                 (self.environment.coredata.regen_guid, buildtype,
                                     self.platform, buildtype, self.platform))
             # Create the solution configuration
-            for p in projlist:
+            for project_index, p in enumerate(projlist):
                 if p[3] is MachineChoice.BUILD:
                     config_platform = self.build_platform
                 else:
@@ -493,11 +493,11 @@ class Vs2010Backend(backends.Backend):
                     # If we're building the solution with Visual Studio's build system, enable building of buildable
                     # projects.  However, if we're building with meson (via --genvslite), then, since each project's
                     # 'build' action just ends up doing the same 'meson compile ...' we don't want the 'solution build'
-                    # repeatedly going off and doing the same 'meson compile ...' multiple times over, so we just
-                    # leave it up to the user to select or build just one project.
-                    # FIXME:  Would be slightly nicer if we could enable building of just one top level target/project,
-                    # but not sure how to identify that.
-                    if not self.gen_lite and \
+                    # repeatedly going off and doing the same 'meson compile ...' multiple times over, so we default
+                    # to building the startup project, which is the first listed project in the solution file by
+                    # default for Visual Studio. The user is free to change this afterwards, but this provides a
+                    # sensible default.
+                    if (not self.gen_lite or project_index == 0) and \
                        p[0] in default_projlist and \
                        not isinstance(self.build.targets[p[0]], build.RunTarget):
                         ofile.write('\t\t{%s}.%s|%s.Build.0 = %s|%s\n' %
@@ -650,6 +650,10 @@ class Vs2010Backend(backends.Backend):
         # This is extremely unhelpful and misleading since the v14x build tools ARE installed.
         ET.SubElement(root, 'Import', Project=r'$(VCTargetsPath)\Microsoft.Cpp.props')
 
+        # This attribute makes sure project names are displayed as expected in solution files even when their project file names differ
+        pname = ET.SubElement(globalgroup, 'ProjectName')
+        pname.text = target_name
+
         if not self.gen_lite: # Plenty of elements aren't necessary for 'makefile'-style project that just redirects to meson builds
             # XXX Wasn't here before for anything but gen_vcxproj , but seems fine?
             ns = ET.SubElement(globalgroup, 'RootNamespace')
@@ -657,8 +661,6 @@ class Vs2010Backend(backends.Backend):
 
             p = ET.SubElement(globalgroup, 'Platform')
             p.text = target_platform
-            pname = ET.SubElement(globalgroup, 'ProjectName')
-            pname.text = target_name
             if self.windows_target_platform_version:
                 ET.SubElement(globalgroup, 'WindowsTargetPlatformVersion').text = self.windows_target_platform_version
             ET.SubElement(globalgroup, 'UseMultiToolTask').text = 'true'