Default to strict mode (/permissive-) from VC15.5

3 files changed, 191 insertions, 189 deletions

diff --git a/build2/cc/compile-rule.cxx b/build2/cc/compile-rule.cxx
index 9e307b6..3ed6075 100644
--- a/build2/cc/compile-rule.cxx
+++ b/build2/cc/compile-rule.cxx
@@ -3183,7 +3183,7 @@ namespace build2
             if (ps)
               psrc.active = true; // Re-arm.
 
-            // Prior to 15u5 (19.12) VC was not using the 'export module M;'
+            // Prior to 15.5 (19.12) VC was not using the 'export module M;'
             // syntax so we use the preprequisite type to distinguish between
             // interface and implementation units.
             //
diff --git a/build2/cxx/init.cxx b/build2/cxx/init.cxx
index 7174121..d32012c 100644
--- a/build2/cxx/init.cxx
+++ b/build2/cxx/init.cxx
@@ -73,245 +73,247 @@ namespace build2
       bool modules (false); auto& v_m (enter ("cxx.features.modules"));
 
       // Translate "latest" and "experimental" to the compiler/version-
-      // appropriate option(s).
+      // appropriate option(s). Experimental is normally like latest with
+      // extra stuff enabled via additional flags. Otherwise translate the
+      // standard value.
       //
-      if (v != nullptr && (*v == "latest" || *v == "experimental"))
-      {
-        // Experimental is like latest with some extra stuff enabled via
-        // additional switches.
-        //
-        const char* o (nullptr);
+      bool experimental (                 v != nullptr && *v == "experimental");
+      bool latest       (experimental || (v != nullptr && *v == "latest"));
+
+      string o;
 
-        switch (ct)
+      switch (cl)
+      {
+      case compiler_class::msvc:
         {
-        case compiler_type::msvc:
+          // C++ standard-wise, with VC you got what you got up until 14.2.
+          // Starting with 14.3 there is now the /std: switch which defaults
+          // to c++14 but can be set to c++latest. And from 15.3 it can be
+          // c++17.
+          //
+          // The question is also whether we should verify that the requested
+          // standard is provided by this VC version. And if so, from which
+          // version should we say VC supports 11, 14, and 17? We should
+          // probably be as loose as possible here since the author will
+          // always be able to tighten (but not loosen) this in the buildfile
+          // (i.e., detect unsupported versions).
+          //
+          // For now we are not going to bother doing this for C++03.
+          //
+          if (latest)
           {
-            // VC14u3 and later has /std:c++latest.
-            //
             if (mj > 19 || (mj == 19 && (mi > 0 || (mi == 0 && p >= 24215))))
               o = "/std:c++latest";
-
-            break;
           }
-        case compiler_type::gcc:
+          else if (v == nullptr)
+            ;
+          else if (*v != "98" && *v != "03")
           {
-            if      (mj >= 8)            o = "-std=c++2a"; // 20
-            else if (mj >= 5)            o = "-std=c++1z"; // 17
-            else if (mj == 4 && mi >= 8) o = "-std=c++1y"; // 14
-            else if (mj == 4 && mi >= 4) o = "-std=c++0x"; // 11
+            bool sup (false);
 
-            break;
-          }
-        case compiler_type::clang:
-          {
-            // Remap Apple versions to vanilla Clang based on the following
-            // release point. Note that Apple no longer discloses the mapping
-            // so it's a guesswork and we try to be conservative. For details
-            // see:
-            //
-            // https://gist.github.com/yamaya/2924292
-            //
-            // 5.1  -> 3.4
-            // 6.0  -> 3.5
-            // 7.0  -> 3.7
-            // 7.3  -> 3.8
-            // 8.0  -> 3.9
-            // 9.0  -> 4.0 (later ones could be 5.0)
-            // 9.1  -> ?
-            // 10.0 -> ?
-            //
-            // Note that this mapping is also used to enable experimental
-            // features below.
-            //
-            if (ci.id.variant == "apple")
+            if      (*v == "11") // C++11 since VS2010/10.0.
+            {
+              sup = mj >= 16;
+            }
+            else if (*v == "14") // C++14 since VS2015/14.0.
+            {
+              sup = mj >= 19;
+            }
+            else if (*v == "17") // C++17 since VS2015/14.0u2.
             {
-              if      (mj >= 9)            {mj = 4; mi = 0;}
-              else if (mj == 8)            {mj = 3; mi = 9;}
-              else if (mj == 7 && mi >= 3) {mj = 3; mi = 8;}
-              else if (mj == 7)            {mj = 3; mi = 7;}
-              else if (mj == 6)            {mj = 3; mi = 5;}
-              else if (mj == 5 && mi >= 1) {mj = 3; mi = 4;}
-              else                         {mj = 3; mi = 0;}
+              // Note: the VC15 compiler version is 19.10.
+              //
+              sup = (mj > 19 ||
+                     (mj == 19 && (mi > 0 || (mi == 0 && p >= 23918))));
             }
 
-            if       (mj >= 5)                         o = "-std=c++2a"; // 20
-            else if  (mj >  3 || (mj == 3 && mi >= 5)) o = "-std=c++1z"; // 17
-            else if  (mj == 3 && mi >= 4)              o = "-std=c++1y"; // 14
-            else     /* ??? */                         o = "-std=c++0x"; // 11
+            if (!sup)
+              fail << "C++" << *v << " is not supported by " << ci.signature <<
+                info << "required by " << project (rs) << '@' << rs.out_path ();
 
-            break;
+            if (mj > 19 || (mj == 19 && mi >= 11)) // 15.3
+            {
+              if      (*v == "14") o = "/std:c++14";
+              else if (*v == "17") o = "/std:c++17";
+            }
+            else if (mj == 19 && (mi > 0 || (mi == 0 && p >= 24215))) // 14.3
+            {
+              if      (*v == "14") o = "/std:c++14";
+              else if (*v == "17") o = "/std:c++latest";
+            }
           }
-        case compiler_type::icc:
-          {
-            if      (mj >= 17)                         o = "-std=c++1z"; // 17
-            else if (mj >  15 || (mj == 15 && p >= 3)) o = "-std=c++1y"; // 14
-            else    /* ??? */                          o = "-std=c++0x"; // 11
 
-            break;
-          }
-        }
+          if (!o.empty ())
+            r.push_back (move (o));
 
-        if (o != nullptr)
-          r.push_back (o);
+          // Starting with 15.5 (19.12) Visual Studio-created projects default
+          // to the strict mode.
+          //
+          if (mj > 19 || (mj == 19 && mi >= 12))
+            r.push_back ("/permissive-");
 
-        if (*v == "experimental")
+          break;
+        }
+      case compiler_class::gcc:
         {
-          // Unless disabled by the user, try to enable C++ modules. Here
-          // we use a tri-state:
-          //
-          // - false        - disabled
-          // - unspecified  - enabled if practically usable
-          // - true         - enabled even if practically unusable
-          //
-          lookup l;
-          if (!(l = rs[v_m]) || cast<bool> (l))
+          if (latest)
           {
             switch (ct)
             {
-            case compiler_type::msvc:
-              {
-                // While modules are supported in VC15u0 (19.10), there is a
-                // bug in separate interface/implementation unit support which
-                // makes them pretty much unusable. This has been fixed in
-                // VC15u3 (19.11). And VC15u5 (19.12) supports the 'export
-                // module M;' syntax.
-                //
-                if (mj > 19 || (mj == 19 && mi >= (l ? 10 : 12)))
-                {
-                  r.push_back (
-                    mj > 19 || mi > 11
-                    ? "/D__cpp_modules=201704"   // p0629r0 (export module M;)
-                    : "/D__cpp_modules=201703"); // n4647   (       module M;)
-
-                  r.push_back ("/experimental:module");
-                  modules = true;
-                }
-                break;
-              }
             case compiler_type::gcc:
               {
-                // Enable starting with GCC 9.0.0 (currently the c++-modules
-                // branch).
-                //
-                if (mj >= 9 &&
-                    ci.version.build.find ("c++-modules") != string::npos)
-                {
-                  // Currently defines __cpp_modules=201810 which is said to
-                  // correspond to p1103 (merged modules).
-                  //
-                  r.push_back ("-fmodules-ts");
-                  modules = true;
-                }
+                if      (mj >= 8)            o = "-std=c++2a"; // 20
+                else if (mj >= 5)            o = "-std=c++1z"; // 17
+                else if (mj == 4 && mi >= 8) o = "-std=c++1y"; // 14
+                else if (mj == 4 && mi >= 4) o = "-std=c++0x"; // 11
+
                 break;
               }
             case compiler_type::clang:
               {
-                // Enable starting with Clang 6.0.0.
+                // Remap Apple versions to vanilla Clang based on the
+                // following release point. Note that Apple no longer
+                // discloses the mapping so it's a guesswork and we try to be
+                // conservative. For details see:
                 //
-                // Note that we are using Apple to vanilla Clang version re-
-                // map from above so may need to update things there as well.
+                // https://gist.github.com/yamaya/2924292
                 //
-                // Also see Clang modules support hack in cc::compile.
+                // 5.1  -> 3.4
+                // 6.0  -> 3.5
+                // 7.0  -> 3.7
+                // 7.3  -> 3.8
+                // 8.0  -> 3.9
+                // 9.0  -> 4.0 (later ones could be 5.0)
+                // 9.1  -> ?
+                // 10.0 -> ?
                 //
-                if (mj >= 6)
+                // Note that this mapping is also used to enable experimental
+                // features below.
+                //
+                if (ci.id.variant == "apple")
                 {
-                  r.push_back ("-D__cpp_modules=201704"); // p0629r0
-                  r.push_back ("-fmodules-ts");
-                  modules = true;
+                  if      (mj >= 9)            {mj = 4; mi = 0;}
+                  else if (mj == 8)            {mj = 3; mi = 9;}
+                  else if (mj == 7 && mi >= 3) {mj = 3; mi = 8;}
+                  else if (mj == 7)            {mj = 3; mi = 7;}
+                  else if (mj == 6)            {mj = 3; mi = 5;}
+                  else if (mj == 5 && mi >= 1) {mj = 3; mi = 4;}
+                  else                         {mj = 3; mi = 0;}
                 }
+
+                if       (mj >= 5)                         o = "-std=c++2a";
+                else if  (mj >  3 || (mj == 3 && mi >= 5)) o = "-std=c++1z";
+                else if  (mj == 3 && mi >= 4)              o = "-std=c++1y";
+                else     /* ??? */                         o = "-std=c++0x";
+
                 break;
               }
             case compiler_type::icc:
-              break; // No modules support yet.
+              {
+                if      (mj >= 17)                         o = "-std=c++1z";
+                else if (mj >  15 || (mj == 15 && p >= 3)) o = "-std=c++1y";
+                else    /* ??? */                          o = "-std=c++0x";
+
+                break;
+              }
+            default:
+              assert (false);
             }
           }
+          else if (v == nullptr)
+            ;
+          else
+          {
+            // Translate 11 to 0x, 14 to 1y, 17 to 1z, and 20 to 2a for
+            // compatibility with older versions of the compilers.
+            //
+            o = "-std=";
+
+            if      (*v == "98") o += "c++98";
+            else if (*v == "03") o += "c++03";
+            else if (*v == "11") o += "c++0x";
+            else if (*v == "14") o += "c++1y";
+            else if (*v == "17") o += "c++1z";
+            else if (*v == "20") o += "c++2a";
+            else o += *v; // In case the user specifies e.g., 'gnu++17'.
+          }
+
+          if (!o.empty ())
+            r.push_back (move (o));
+
+          break;
         }
       }
-      else
+
+      if (experimental)
       {
-        // Otherwise translate the standard value.
+        // Unless disabled by the user, try to enable C++ modules. Here we use
+        // a tri-state:
         //
-        switch (cl)
+        // - false        - disabled
+        // - unspecified  - enabled if practically usable
+        // - true         - enabled even if practically unusable
+        //
+        lookup l;
+        if (!(l = rs[v_m]) || cast<bool> (l))
         {
-        case compiler_class::msvc:
+          switch (ct)
           {
-            // C++ standard-wise, with VC you got what you got up until 14u2.
-            // Starting with 14u3 there is now the /std: switch which defaults
-            // to c++14 but can be set to c++latest. And from 15u3 it can be
-            // c++17.
-            //
-            // The question is also whether we should verify that the
-            // requested standard is provided by this VC version. And if so,
-            // from which version should we say VC supports 11, 14, and 17? We
-            // should probably be as loose as possible here since the author
-            // will always be able to tighten (but not loosen) this in the
-            // buildfile (i.e., detect unsupported versions).
-            //
-            // For now we are not going to bother doing this for C++03.
-            //
-            if (v == nullptr)
-              ;
-            else if (*v != "98" && *v != "03")
+          case compiler_type::msvc:
             {
-              bool sup (false);
-
-              if      (*v == "11") // C++11 since VS2010/10.0.
+              // While modules are supported in VC15.0 (19.10), there is a bug
+              // in separate interface/implementation unit support which makes
+              // them pretty much unusable. This has been fixed in VC15.3
+              // (19.11). And VC15.5 (19.12) supports the 'export module M;'
+              // syntax.
+              //
+              if (mj > 19 || (mj == 19 && mi >= (l ? 10 : 12)))
               {
-                sup = mj >= 16;
-              }
-              else if (*v == "14") // C++14 since VS2015/14.0.
-              {
-                sup = mj >= 19;
-              }
-              else if (*v == "17") // C++17 since VS2015/14.0u2.
-              {
-                // Note: the VC15 compiler version is 19.10.
-                //
-                sup = (mj > 19 ||
-                       (mj == 19 && (mi > 0 || (mi == 0 && p >= 23918))));
-              }
-
-              if (!sup)
-                fail << "C++" << *v << " is not supported by "
-                     << ci.signature <<
-                  info << "required by " << project (rs) << '@'
-                     << rs.out_path ();
+                r.push_back (
+                  mj > 19 || mi > 11
+                  ? "/D__cpp_modules=201704"   // p0629r0 (export module M;)
+                  : "/D__cpp_modules=201703"); // n4647   (       module M;)
 
-              if (mj > 19 || (mj == 19 && mi >= 11)) // 15u3
-              {
-                if      (*v == "14") r.push_back ("/std:c++14");
-                else if (*v == "17") r.push_back ("/std:c++17");
+                r.push_back ("/experimental:module");
+                modules = true;
               }
-              else if (mj == 19 && (mi > 0 || (mi == 0 && p >= 24215))) // 14u3
+              break;
+            }
+          case compiler_type::gcc:
+            {
+              // Enable starting with GCC 9.0.0 (currently the c++-modules
+              // branch).
+              //
+              if (mj >= 9 &&
+                  ci.version.build.find ("c++-modules") != string::npos)
               {
-                if      (*v == "14") r.push_back ("/std:c++14");
-                else if (*v == "17") r.push_back ("/std:c++latest");
+                // Currently defines __cpp_modules=201810 which is said to
+                // correspond to p1103 (merged modules).
+                //
+                r.push_back ("-fmodules-ts");
+                modules = true;
               }
+              break;
             }
-            break;
-          }
-        case compiler_class::gcc:
-          {
-            // Translate 11 to 0x, 14 to 1y, 17 to 1z, and 20 to 2a for
-            // compatibility with older versions of the compilers.
-            //
-            if (v == nullptr)
-              ;
-            else
+          case compiler_type::clang:
             {
-              string o ("-std=");
-
-              if      (*v == "98") o += "c++98";
-              else if (*v == "03") o += "c++03";
-              else if (*v == "11") o += "c++0x";
-              else if (*v == "14") o += "c++1y";
-              else if (*v == "17") o += "c++1z";
-              else if (*v == "20") o += "c++2a";
-              else o += *v; // In case the user specifies e.g., 'gnu++17'.
-
-              r.push_back (move (o));
+              // Enable starting with Clang 6.0.0.
+              //
+              // Note that we are using Apple to vanilla Clang version re-map
+              // from above so may need to update things there as well.
+              //
+              // Also see Clang modules support hack in cc::compile.
+              //
+              if (mj >= 6)
+              {
+                r.push_back ("-D__cpp_modules=201704"); // p0629r0
+                r.push_back ("-fmodules-ts");
+                modules = true;
+              }
+              break;
             }
-            break;
+          case compiler_type::icc:
+            break; // No modules support yet.
           }
         }
       }
diff --git a/build2/target.hxx b/build2/target.hxx
index fafb689..cb1163f 100644
--- a/build2/target.hxx
+++ b/build2/target.hxx
@@ -51,7 +51,7 @@ namespace build2
   //
   // Note that max size for the "small capture optimization" in std::function
   // ranges (in pointer sizes) from 0 (GCC prior to 5) to 2 (GCC 5) to 6 (VC
-  // 14u2). With the size ranging (in bytes for 64-bit target) from 32 (GCC)
+  // 14.2). With the size ranging (in bytes for 64-bit target) from 32 (GCC)
   // to 64 (VC).
   //
   using recipe_function = target_state (action, const target&);