dwarf/line: Fixed DirIdx (index starts at one) (#1873)

* Fixed DirIdx (index starts at one)

I am using the elf to load C++ based elf and there the index starts at one and not zero, hence the minor fix.

* Added test

* Added proper test for c-generated elf & replaced index offset by adding build dir

* Changed other IncludeDir test

* Format fix & replace print with actual test

* Format fixes @derekparker requested.

pkg/dwarf/line/line_parser.go

@@ -74,9 +74,7 @@ func Parse(compdir string, buf *bytes.Buffer, logfn func(string, ...interface{})
 	dbl.Logf = logfn
 	dbl.staticBase = staticBase
 	dbl.Lookup = make(map[string]*FileEntry)
-	if compdir != "" {
 	dbl.IncludeDirs = append(dbl.IncludeDirs, compdir)
-	}
 
 	dbl.stateMachineCache = make(map[uint64]*StateMachine)
 	dbl.lastMachineCache = make(map[uint64]*StateMachine)

pkg/dwarf/line/line_parser_test.go

@@ -109,10 +109,19 @@ func testDebugLinePrologueParser(p string, t *testing.T) {
 			}
 		}
 
-		if len(dbl.IncludeDirs) != 0 {
+		if len(dbl.IncludeDirs) != 1 {
 			t.Fatal("Include dirs not parsed correctly")
 		}
 
+		for _, ln := range dbl.Lookup {
+			if ln.Path == "<autogenerated>" {
+				continue
+			}
+ 			if _, err := os.Stat(ln.Path); err != nil {
+				t.Fatalf("Invalid input path %s: %s\n", ln.Path, err)
+			}
+		}
+
 		for _, n := range dbl.FileNames {
 			if strings.Contains(n.Path, "/_fixtures/testnextprog.go") {
 				mainFileFound = true
@@ -289,3 +298,43 @@ func BenchmarkPCToLine(b *testing.B) {
 		runTestPCToLine(b, lineInfos, entries, basePCs, false, 0x10000)
 	}
 }
+
+func TestDebugLineC(t * testing.T) {
+	p, err := filepath.Abs("../../../_fixtures/debug_line_c_data")
+	if err != nil {
+		t.Fatal("Could not find test data", p, err)
+	}
+
+	data, err := ioutil.ReadFile(p)
+	if err != nil {
+		t.Fatal("Could not read test data", err)
+	}
+
+	parsed := ParseAll(data, nil, 0, true)
+
+	if len(parsed) == 0 {
+		t.Fatal("Parser result is empty")
+	}
+
+	file := []string{"main.c", "/mnt/c/develop/delve/_fixtures/main.c" ,"/usr/lib/gcc/x86_64-linux-gnu/7/include/stddef.h",
+			 "/usr/include/x86_64-linux-gnu/bits/types.h" ,"/usr/include/x86_64-linux-gnu/bits/libio.h", "/usr/include/stdio.h",
+			 "/usr/include/x86_64-linux-gnu/bits/sys_errlist.h"}
+
+	for _, ln := range parsed {
+		if len(ln.FileNames) == 0 {
+			t.Fatal("Parser could not parse Filenames")
+		}
+		for _, fn := range ln.FileNames {
+			found := false
+			for _, cmp := range file {
+				if filepath.ToSlash(fn.Path) == cmp {
+					found = true
+					break
+				}
+			}
+			if !found {
+				t.Fatalf("Found %s does not appear in the filelist\n", fn.Path)
+			}
+		}
+	}
+}