Giant blob of minor changes

[dotfiles/.git] / .config / coc / extensions / coc-go-data / tools / pkg / mod / golang.org / x / tools@v0.0.0-20201028153306-37f0764111ff / go / analysis / passes / shift / shift.go

diff --git a/.config/coc/extensions/coc-go-data/tools/pkg/mod/golang.org/x/tools@v0.0.0-20201028153306-37f0764111ff/go/analysis/passes/shift/shift.go b/.config/coc/extensions/coc-go-data/tools/pkg/mod/golang.org/x/tools@v0.0.0-20201028153306-37f0764111ff/go/analysis/passes/shift/shift.go
new file mode 100644 (file)
index 0000000..1f3df07
--- /dev/null
+++ b/.config/coc/extensions/coc-go-data/tools/pkg/mod/golang.org/x/tools@v0.0.0-20201028153306-37f0764111ff/go/analysis/passes/shift/shift.go
@@ -0,0 +1,101 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package shift defines an Analyzer that checks for shifts that exceed
+// the width of an integer.
+package shift
+
+// TODO(adonovan): integrate with ctrflow (CFG-based) dead code analysis. May
+// have impedance mismatch due to its (non-)treatment of constant
+// expressions (such as runtime.GOARCH=="386").
+
+import (
+       "go/ast"
+       "go/constant"
+       "go/token"
+
+       "golang.org/x/tools/go/analysis"
+       "golang.org/x/tools/go/analysis/passes/inspect"
+       "golang.org/x/tools/go/analysis/passes/internal/analysisutil"
+       "golang.org/x/tools/go/ast/inspector"
+)
+
+const Doc = "check for shifts that equal or exceed the width of the integer"
+
+var Analyzer = &analysis.Analyzer{
+       Name:     "shift",
+       Doc:      Doc,
+       Requires: []*analysis.Analyzer{inspect.Analyzer},
+       Run:      run,
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+       inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+
+       // Do a complete pass to compute dead nodes.
+       dead := make(map[ast.Node]bool)
+       nodeFilter := []ast.Node{
+               (*ast.IfStmt)(nil),
+               (*ast.SwitchStmt)(nil),
+       }
+       inspect.Preorder(nodeFilter, func(n ast.Node) {
+               // TODO(adonovan): move updateDead into this file.
+               updateDead(pass.TypesInfo, dead, n)
+       })
+
+       nodeFilter = []ast.Node{
+               (*ast.AssignStmt)(nil),
+               (*ast.BinaryExpr)(nil),
+       }
+       inspect.Preorder(nodeFilter, func(node ast.Node) {
+               if dead[node] {
+                       // Skip shift checks on unreachable nodes.
+                       return
+               }
+
+               switch node := node.(type) {
+               case *ast.BinaryExpr:
+                       if node.Op == token.SHL || node.Op == token.SHR {
+                               checkLongShift(pass, node, node.X, node.Y)
+                       }
+               case *ast.AssignStmt:
+                       if len(node.Lhs) != 1 || len(node.Rhs) != 1 {
+                               return
+                       }
+                       if node.Tok == token.SHL_ASSIGN || node.Tok == token.SHR_ASSIGN {
+                               checkLongShift(pass, node, node.Lhs[0], node.Rhs[0])
+                       }
+               }
+       })
+       return nil, nil
+}
+
+// checkLongShift checks if shift or shift-assign operations shift by more than
+// the length of the underlying variable.
+func checkLongShift(pass *analysis.Pass, node ast.Node, x, y ast.Expr) {
+       if pass.TypesInfo.Types[x].Value != nil {
+               // Ignore shifts of constants.
+               // These are frequently used for bit-twiddling tricks
+               // like ^uint(0) >> 63 for 32/64 bit detection and compatibility.
+               return
+       }
+
+       v := pass.TypesInfo.Types[y].Value
+       if v == nil {
+               return
+       }
+       amt, ok := constant.Int64Val(v)
+       if !ok {
+               return
+       }
+       t := pass.TypesInfo.Types[x].Type
+       if t == nil {
+               return
+       }
+       size := 8 * pass.TypesSizes.Sizeof(t)
+       if amt >= size {
+               ident := analysisutil.Format(pass.Fset, x)
+               pass.ReportRangef(node, "%s (%d bits) too small for shift of %d", ident, size, amt)
+       }
+}