go/{analysis,packages}: add TypesSizes

Many Analyzers need to measure the width of an integer and all today
use hacks. This change causes analysis.Pass to retain and expose the
type sizing function used during type checking.

This in turn requires go/packages to retain and expose the type sizing
function in Packages.TypesSizes, which addresses a longstanding need
among many of its clients.

Change-Id: Ia8362019bcde34c10cb4fbc38cfdfddcbef3eb5c
Reviewed-on: https://go-review.googlesource.com/c/158317
Reviewed-by: Michael Matloob <matloob@golang.org>
Run-TryBot: Michael Matloob <matloob@golang.org>

go/analysis/analysis.go

@@ -87,6 +87,7 @@ type Pass struct {
 	OtherFiles []string       // names of non-Go files of this package
 	Pkg        *types.Package // type information about the package
 	TypesInfo  *types.Info    // type information about the syntax trees
+	TypesSizes types.Sizes    // function for computing sizes of types
 
 	// Report reports a Diagnostic, a finding about a specific location
 	// in the analyzed source code such as a potential mistake.

go/analysis/internal/checker/checker.go

@@ -492,6 +492,7 @@ func (act *action) execOnce() {
 		OtherFiles:        act.pkg.OtherFiles,
 		Pkg:               act.pkg.Types,
 		TypesInfo:         act.pkg.TypesInfo,
+		TypesSizes:        act.pkg.TypesSizes,
 		ResultOf:          inputs,
 		Report:            func(d analysis.Diagnostic) { act.diagnostics = append(act.diagnostics, d) },
 		ImportObjectFact:  act.importObjectFact,

go/analysis/passes/asmdecl/asmdecl.go

@@ -114,7 +114,8 @@ func init() {
 			// library we cannot assume types.SizesFor is consistent with arches.
 			// For now, assume 64-bit norms and print a warning.
 			// But this warning should really be deferred until we attempt to use
-			// arch, which is very unlikely.
+			// arch, which is very unlikely. Better would be
+			// to defer size computation until we have Pass.TypesSizes.
 			arch.sizes = types.SizesFor("gc", "amd64")
 			log.Printf("unknown architecture %s", arch.name)
 		}

go/analysis/passes/cgocall/cgocall.go

@@ -9,7 +9,6 @@ package cgocall
 import (
 	"fmt"
 	"go/ast"
-	"go/build"
 	"go/format"
 	"go/parser"
 	"go/token"
@@ -45,7 +44,7 @@ func run(pass *analysis.Pass) (interface{}, error) {
 		return nil, nil // doesn't use cgo
 	}
 
-	cgofiles, info, err := typeCheckCgoSourceFiles(pass.Fset, pass.Pkg, pass.Files, pass.TypesInfo)
+	cgofiles, info, err := typeCheckCgoSourceFiles(pass.Fset, pass.Pkg, pass.Files, pass.TypesInfo, pass.TypesSizes)
 	if err != nil {
 		return nil, err
 	}
@@ -171,7 +170,7 @@ func checkCgo(fset *token.FileSet, f *ast.File, info *types.Info, reportf func(t
 // limited ourselves here to preserving function bodies and initializer
 // expressions since that is all that the cgocall analyzer needs.
 //
-func typeCheckCgoSourceFiles(fset *token.FileSet, pkg *types.Package, files []*ast.File, info *types.Info) ([]*ast.File, *types.Info, error) {
+func typeCheckCgoSourceFiles(fset *token.FileSet, pkg *types.Package, files []*ast.File, info *types.Info, sizes types.Sizes) ([]*ast.File, *types.Info, error) {
 	const thispkg = "·this·"
 
 	// Which files are cgo files?
@@ -269,8 +268,7 @@ func typeCheckCgoSourceFiles(fset *token.FileSet, pkg *types.Package, files []*a
 		Importer: importerFunc(func(path string) (*types.Package, error) {
 			return importMap[path], nil
 		}),
-		// TODO(adonovan): Sizes should probably be provided by analysis.Pass.
+		Sizes: sizes,
-		Sizes: types.SizesFor("gc", build.Default.GOARCH),
 		Error: func(error) {}, // ignore errors (e.g. unused import)
 	}
 

go/analysis/passes/printf/types.go

@@ -2,7 +2,6 @@ package printf
 
 import (
 	"go/ast"
-	"go/build"
 	"go/types"
 
 	"golang.org/x/tools/go/analysis"
@@ -235,5 +234,3 @@ func matchStructArgType(pass *analysis.Pass, t printfArgType, typ *types.Struct,
 	}
 	return true
 }
-
-var archSizes = types.SizesFor("gc", build.Default.GOARCH)

go/analysis/passes/shift/shift.go

@@ -12,10 +12,8 @@ package shift
 
 import (
 	"go/ast"
-	"go/build"
 	"go/constant"
 	"go/token"
-	"go/types"
 
 	"golang.org/x/tools/go/analysis"
 	"golang.org/x/tools/go/analysis/passes/inspect"
@@ -93,36 +91,9 @@ func checkLongShift(pass *analysis.Pass, node ast.Node, x, y ast.Expr) {
 	if t == nil {
 		return
 	}
-	b, ok := t.Underlying().(*types.Basic)
+	size := 8 * pass.TypesSizes.Sizeof(t)
-	if !ok {
-		return
-	}
-	var size int64
-	switch b.Kind() {
-	case types.Uint8, types.Int8:
-		size = 8
-	case types.Uint16, types.Int16:
-		size = 16
-	case types.Uint32, types.Int32:
-		size = 32
-	case types.Uint64, types.Int64:
-		size = 64
-	case types.Int, types.Uint:
-		size = uintBitSize
-	case types.Uintptr:
-		size = uintptrBitSize
-	default:
-		return
-	}
 	if amt >= size {
 		ident := analysisutil.Format(pass.Fset, x)
 		pass.Reportf(node.Pos(), "%s (%d bits) too small for shift of %d", ident, size, amt)
 	}
 }
-
-var (
-	uintBitSize    = 8 * archSizes.Sizeof(types.Typ[types.Uint])
-	uintptrBitSize = 8 * archSizes.Sizeof(types.Typ[types.Uintptr])
-)
-
-var archSizes = types.SizesFor("gc", build.Default.GOARCH)

go/analysis/unitchecker/unitchecker.go

@@ -329,6 +329,7 @@ func run(fset *token.FileSet, cfg *Config, analyzers []*analysis.Analyzer) ([]re
 				OtherFiles:        cfg.NonGoFiles,
 				Pkg:               pkg,
 				TypesInfo:         info,
+				TypesSizes:        tc.Sizes,
 				ResultOf:          inputs,
 				Report:            func(d analysis.Diagnostic) { act.diagnostics = append(act.diagnostics, d) },
 				ImportObjectFact:  facts.ImportObjectFact,

go/packages/packages.go

@@ -250,6 +250,9 @@ type Package struct {
 	// TypesInfo provides type information about the package's syntax trees.
 	// It is set only when Syntax is set.
 	TypesInfo *types.Info
+
+	// TypesSizes provides the effective size function for types in TypesInfo.
+	TypesSizes types.Sizes
 }
 
 // An Error describes a problem with a package's metadata, syntax, or types.
@@ -582,6 +585,7 @@ func (ld *loader) loadPackage(lpkg *loaderPackage) {
 		lpkg.Fset = ld.Fset
 		lpkg.Syntax = []*ast.File{}
 		lpkg.TypesInfo = new(types.Info)
+		lpkg.TypesSizes = ld.sizes
 		return
 	}
 
@@ -669,6 +673,7 @@ func (ld *loader) loadPackage(lpkg *loaderPackage) {
 		Scopes:     make(map[ast.Node]*types.Scope),
 		Selections: make(map[*ast.SelectorExpr]*types.Selection),
 	}
+	lpkg.TypesSizes = ld.sizes
 
 	importer := importerFunc(func(path string) (*types.Package, error) {
 		if path == "unsafe" {