1 files changed, 70 insertions, 0 deletions
diff --git a/vendor/honnef.co/go/tools/internal/sharedcheck/lint.go b/vendor/honnef.co/go/tools/internal/sharedcheck/lint.go
new file mode 100644
index 0000000..5f62fc2
--- /dev/null
+++ b/vendor/honnef.co/go/tools/internal/sharedcheck/lint.go
@@ -0,0 +1,70 @@
+package sharedcheck
+
+import (
+	"go/ast"
+	"go/types"
+
+	"honnef.co/go/tools/lint"
+	"honnef.co/go/tools/ssa"
+)
+
+func CheckRangeStringRunes(nodeFns map[ast.Node]*ssa.Function, j *lint.Job) {
+	fn := func(node ast.Node) bool {
+		rng, ok := node.(*ast.RangeStmt)
+		if !ok || !lint.IsBlank(rng.Key) {
+			return true
+		}
+		ssafn := nodeFns[rng]
+		if ssafn == nil {
+			return true
+		}
+		v, _ := ssafn.ValueForExpr(rng.X)
+
+		// Check that we're converting from string to []rune
+		val, _ := v.(*ssa.Convert)
+		if val == nil {
+			return true
+		}
+		Tsrc, ok := val.X.Type().(*types.Basic)
+		if !ok || Tsrc.Kind() != types.String {
+			return true
+		}
+		Tdst, ok := val.Type().(*types.Slice)
+		if !ok {
+			return true
+		}
+		TdstElem, ok := Tdst.Elem().(*types.Basic)
+		if !ok || TdstElem.Kind() != types.Int32 {
+			return true
+		}
+
+		// Check that the result of the conversion is only used to
+		// range over
+		refs := val.Referrers()
+		if refs == nil {
+			return true
+		}
+
+		// Expect two refs: one for obtaining the length of the slice,
+		// one for accessing the elements
+		if len(lint.FilterDebug(*refs)) != 2 {
+			// TODO(dh): right now, we check that only one place
+			// refers to our slice. This will miss cases such as
+			// ranging over the slice twice. Ideally, we'd ensure that
+			// the slice is only used for ranging over (without
+			// accessing the key), but that is harder to do because in
+			// SSA form, ranging over a slice looks like an ordinary
+			// loop with index increments and slice accesses. We'd
+			// have to look at the associated AST node to check that
+			// it's a range statement.
+			return true
+		}
+
+		j.Errorf(rng, "should range over string, not []rune(string)")
+
+		return true
+	}
+	for _, f := range j.Program.Files {
+		ast.Inspect(f, fn)
+	}
+}