Fix MSVC++ portability issues (#3812)

src/V3DfgDfgToAst.cpp

@@ -100,21 +100,29 @@ AstShiftRS* makeNode<AstShiftRS, DfgShiftRS, AstNodeExpr*, AstNodeExpr*>(  //
 template <>
 AstCCast* makeNode<AstCCast, DfgCCast, AstNodeExpr*>(const DfgCCast* vtxp, AstNodeExpr*) {
     vtxp->v3fatalSrc("not implemented");
+    VL_UNREACHABLE;
+    return nullptr;  // LCOV_EXCL_LINE
 }
 template <>
 AstAtoN* makeNode<AstAtoN, DfgAtoN, AstNodeExpr*>(const DfgAtoN* vtxp, AstNodeExpr*) {
     vtxp->v3fatalSrc("not implemented");
+    VL_UNREACHABLE;
+    return nullptr;  // LCOV_EXCL_LINE
 }
 template <>
 AstCompareNN*
 makeNode<AstCompareNN, DfgCompareNN, AstNodeExpr*, AstNodeExpr*>(const DfgCompareNN* vtxp,
                                                                  AstNodeExpr*, AstNodeExpr*) {
     vtxp->v3fatalSrc("not implemented");
+    VL_UNREACHABLE;
+    return nullptr;  // LCOV_EXCL_LINE
 }
 template <>
 AstSliceSel* makeNode<AstSliceSel, DfgSliceSel, AstNodeExpr*, AstNodeExpr*, AstNodeExpr*>(
     const DfgSliceSel* vtxp, AstNodeExpr*, AstNodeExpr*, AstNodeExpr*) {
     vtxp->v3fatalSrc("not implemented");
+    VL_UNREACHABLE;
+    return nullptr;  // LCOV_EXCL_LINE
 }
 // LCOV_EXCL_STOP
 

src/V3Os.cpp

@@ -80,10 +80,10 @@ string V3Os::getenvStr(const string& envvar, const string& defaultValue) {
 #if defined(_MSC_VER)
     // Note: MinGW does not offer _dupenv_s
     const char* envvalue = nullptr;
-    _dupenv_s(&envvalue, nullptr, envvar.c_str());
+    _dupenv_s((char **)&envvalue, nullptr, envvar.c_str());
     if (envvalue != nullptr) {
         const std::string result{envvalue};
-        free(envvalue);
+        free((void *)envvalue);
         ret = result;
     } else {
         ret = defaultValue;

src/bisonpre

@@ -45,7 +45,7 @@ def process():
     if status != 0:
         unlink_outputs()
         sys.exit("bisonpre: %Error: " + Args.yacc + " version " +
-                 Bison_Version + " run failed due to errors\n")
+                 str(Bison_Version) + " run failed due to errors\n")
 
     clean_output(tmp_prefix() + ".output",
                  output_prefix() + ".output", True, False)