fix: improve golang externs (#1133)

* fix: improve golang externs

Author: ajewellamz

Diff for: StandardLibrary/runtimes/go/ImplementationFromDafny-go/FileIO/externs.go

@@ -5,6 +5,7 @@ import (
 	os "os"
 	"path/filepath"
 
+	"github.com/dafny-lang/DafnyRuntimeGo/v4/dafny"
 	_dafny "github.com/dafny-lang/DafnyRuntimeGo/v4/dafny"
 )
 
@@ -28,8 +29,7 @@ func (_static CompanionStruct_Default___) INTERNAL_ReadBytesFromFile(path _dafny
 
 	dat, err := ioutil.ReadFile(p)
 	if err != nil {
-		errAsSequence := _dafny.UnicodeSeqOfUtf8Bytes(err.Error())
-		return true, _dafny.EmptySeq, errAsSequence
+		return true, _dafny.EmptySeq, _dafny.SeqOfChars([]dafny.Char(err.Error())...)
 	}
 	datAsSequence := _dafny.SeqOfBytes(dat)
 	return false, datAsSequence, _dafny.EmptySeq
@@ -53,8 +53,7 @@ func (_static CompanionStruct_Default___) INTERNAL_WriteBytesToFile(path _dafny.
 	bytesArray := _dafny.ToByteArray(bytes)
 	err := ioutil.WriteFile(p, bytesArray, 0644)
 	if err != nil {
-		errAsSequence := _dafny.UnicodeSeqOfUtf8Bytes(err.Error())
-		return true, errAsSequence
+		return true, _dafny.SeqOfChars([]dafny.Char(err.Error())...)
 	}
 	return false, _dafny.EmptySeq
 }
@@ -73,21 +72,24 @@ func (_static CompanionStruct_Default___) INTERNAL_AppendBytesToFile(path _dafny
 	}()
 
 	// Create directories
-	os.MkdirAll(filepath.Dir(p), os.ModePerm)
+	err := os.MkdirAll(filepath.Dir(p), os.ModePerm)
+	if err != nil {
+		return true, _dafny.SeqOfChars([]dafny.Char(err.Error())...)
+	}
 
 	bytesArray := _dafny.ToByteArray(bytes)
 
 	f, err := os.OpenFile(p, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
 	if err != nil {
-		return true, _dafny.UnicodeSeqOfUtf8Bytes(err.Error())
+		return true, _dafny.SeqOfChars([]dafny.Char(err.Error())...)
 	}
 
 	if _, err := f.Write(bytesArray); err != nil {
-		return true, _dafny.UnicodeSeqOfUtf8Bytes(err.Error())
+		return true, _dafny.SeqOfChars([]dafny.Char(err.Error())...)
 	}
 
 	if err := f.Close(); err != nil {
-		return true, _dafny.UnicodeSeqOfUtf8Bytes(err.Error())
+		return true, _dafny.SeqOfChars([]dafny.Char(err.Error())...)
 	}
 
 	return false, _dafny.EmptySeq

Diff for: StandardLibrary/runtimes/go/ImplementationFromDafny-go/Time_/externs.go

@@ -38,7 +38,10 @@ func (CompanionStruct_Default___) GetProcessCpuTimeMillis() int64 {
 }
 
 func GetProcessCpuTimeMillis() int64 {
-	usage := new(syscall.Rusage)
-	syscall.Getrusage(syscall.RUSAGE_SELF, usage)
+	var usage syscall.Rusage
+	err := syscall.Getrusage(syscall.RUSAGE_SELF, &usage)
+	if err != nil {
+		return 0
+	}
 	return (usage.Utime.Nano() + usage.Stime.Nano()) / 1000000
 }

Diff for: StandardLibrary/test/GetOpt.dfy

@@ -152,7 +152,6 @@ module GetOptTest {
                              ]);
     var x :- expect GetOptions(MyOptions, ["cmd", "--help"]);
     var y :- expect NeedsHelp(MyOptions, x);
-    print "\n", y, "\n";
   }
 
   method {:test} TestHelpFail() {
@@ -196,11 +195,9 @@ module GetOptTest {
 
     x :- expect GetOptions(MyOptions, ["MyProg", "--help"]);
     var y :- expect NeedsHelp(MyOptions, x);
-    print "\n", y, "\n";
 
     x :- expect GetOptions(MyOptions, ["MyProg", "command", "--help"]);
     y :- expect NeedsHelp(MyOptions, x);
-    print "\n", y, "\n";
   }
 
   method {:test} TestDefault() {

Diff for: StandardLibrary/test/TestString.dfy

@@ -47,4 +47,12 @@ module TestStrings {
     expect y == [1,2,3,4,5];
   }
 
+  // ensure that FileIO error are returned properly, and not a panic! or the like
+  // This fails to fail on Windows+Dotnet, becasue \ instead of /
+  // method {:test} TestBadFileIO()
+  // {
+  //   var x := WriteBytesToFile("/../../MyFile", [1,2,3,4,5]);
+  //   expect x.Failure?;
+  // }
+
 }