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Thie CL changes cmd/compile/internal/syntax to give the gc half of
the compiler more control over pragma handling, so that it can prepare
better errors, diagnose misuse, and so on. Before, the API between
the two was hard-coded as a uint16. Now it is an interface{}.
This should set us up better for future directives.

In addition to the split, this CL emits a "misplaced compiler directive"
error for any directive that is in a place where it has no effect.
I've certainly been confused in the past by adding comments
that were doing nothing and not realizing it. This should help
avoid that kind of confusion.

The rule, now applied consistently, is that a //go: directive
must appear on a line by itself immediately before the declaration
specifier it means to apply to. See cmd/compile/doc.go for
precise text and test/directive.go for examples.

This may cause some code to stop compiling, but that code
was broken. For example, this code formerly applied the
//go:noinline to f (not c) but now will fail to compile:

	//go:noinline
	const c = 1

	func f() {}

Change-Id: Ieba9b8d90a27cfab25de79d2790a895cefe5296f
Reviewed-on: https://go-review.googlesource.com/c/go/+/228578
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
4 contributors

Users who have contributed to this file

// Copyright 2016 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 syntax
// ----------------------------------------------------------------------------
// Nodes
type Node interface {
// Pos() returns the position associated with the node as follows:
// 1) The position of a node representing a terminal syntax production
// (Name, BasicLit, etc.) is the position of the respective production
// in the source.
// 2) The position of a node representing a non-terminal production
// (IndexExpr, IfStmt, etc.) is the position of a token uniquely
// associated with that production; usually the left-most one
// ('[' for IndexExpr, 'if' for IfStmt, etc.)
Pos() Pos
aNode()
}
type node struct {
// commented out for now since not yet used
// doc *Comment // nil means no comment(s) attached
pos Pos
}
func (n *node) Pos() Pos { return n.pos }
func (*node) aNode() {}
// ----------------------------------------------------------------------------
// Files
// package PkgName; DeclList[0], DeclList[1], ...
type File struct {
Pragma Pragma
PkgName *Name
DeclList []Decl
Lines uint
node
}
// ----------------------------------------------------------------------------
// Declarations
type (
Decl interface {
Node
aDecl()
}
// Path
// LocalPkgName Path
ImportDecl struct {
Group *Group // nil means not part of a group
Pragma Pragma
LocalPkgName *Name // including "."; nil means no rename present
Path *BasicLit
decl
}
// NameList
// NameList = Values
// NameList Type = Values
ConstDecl struct {
Group *Group // nil means not part of a group
Pragma Pragma
NameList []*Name
Type Expr // nil means no type
Values Expr // nil means no values
decl
}
// Name Type
TypeDecl struct {
Group *Group // nil means not part of a group
Pragma Pragma
Name *Name
Alias bool
Type Expr
decl
}
// NameList Type
// NameList Type = Values
// NameList = Values
VarDecl struct {
Group *Group // nil means not part of a group
Pragma Pragma
NameList []*Name
Type Expr // nil means no type
Values Expr // nil means no values
decl
}
// func Name Type { Body }
// func Name Type
// func Receiver Name Type { Body }
// func Receiver Name Type
FuncDecl struct {
Pragma Pragma
Recv *Field // nil means regular function
Name *Name
Type *FuncType
Body *BlockStmt // nil means no body (forward declaration)
decl
}
)
type decl struct{ node }
func (*decl) aDecl() {}
// All declarations belonging to the same group point to the same Group node.
type Group struct {
dummy int // not empty so we are guaranteed different Group instances
}
// ----------------------------------------------------------------------------
// Expressions
type (
Expr interface {
Node
aExpr()
}
// Placeholder for an expression that failed to parse
// correctly and where we can't provide a better node.
BadExpr struct {
expr
}
// Value
Name struct {
Value string
expr
}
// Value
BasicLit struct {
Value string
Kind LitKind
Bad bool // true means the literal Value has syntax errors
expr
}
// Type { ElemList[0], ElemList[1], ... }
CompositeLit struct {
Type Expr // nil means no literal type
ElemList []Expr
NKeys int // number of elements with keys
Rbrace Pos
expr
}
// Key: Value
KeyValueExpr struct {
Key, Value Expr
expr
}
// func Type { Body }
FuncLit struct {
Type *FuncType
Body *BlockStmt
expr
}
// (X)
ParenExpr struct {
X Expr
expr
}
// X.Sel
SelectorExpr struct {
X Expr
Sel *Name
expr
}
// X[Index]
IndexExpr struct {
X Expr
Index Expr
expr
}
// X[Index[0] : Index[1] : Index[2]]
SliceExpr struct {
X Expr
Index [3]Expr
// Full indicates whether this is a simple or full slice expression.
// In a valid AST, this is equivalent to Index[2] != nil.
// TODO(mdempsky): This is only needed to report the "3-index
// slice of string" error when Index[2] is missing.
Full bool
expr
}
// X.(Type)
AssertExpr struct {
X Expr
Type Expr
expr
}
// X.(type)
// Lhs := X.(type)
TypeSwitchGuard struct {
Lhs *Name // nil means no Lhs :=
X Expr // X.(type)
expr
}
Operation struct {
Op Operator
X, Y Expr // Y == nil means unary expression
expr
}
// Fun(ArgList[0], ArgList[1], ...)
CallExpr struct {
Fun Expr
ArgList []Expr // nil means no arguments
HasDots bool // last argument is followed by ...
expr
}
// ElemList[0], ElemList[1], ...
ListExpr struct {
ElemList []Expr
expr
}
// [Len]Elem
ArrayType struct {
// TODO(gri) consider using Name{"..."} instead of nil (permits attaching of comments)
Len Expr // nil means Len is ...
Elem Expr
expr
}
// []Elem
SliceType struct {
Elem Expr
expr
}
// ...Elem
DotsType struct {
Elem Expr
expr
}
// struct { FieldList[0] TagList[0]; FieldList[1] TagList[1]; ... }
StructType struct {
FieldList []*Field
TagList []*BasicLit // i >= len(TagList) || TagList[i] == nil means no tag for field i
expr
}
// Name Type
// Type
Field struct {
Name *Name // nil means anonymous field/parameter (structs/parameters), or embedded interface (interfaces)
Type Expr // field names declared in a list share the same Type (identical pointers)
node
}
// interface { MethodList[0]; MethodList[1]; ... }
InterfaceType struct {
MethodList []*Field
expr
}
FuncType struct {
ParamList []*Field
ResultList []*Field
expr
}
// map[Key]Value
MapType struct {
Key, Value Expr
expr
}
// chan Elem
// <-chan Elem
// chan<- Elem
ChanType struct {
Dir ChanDir // 0 means no direction
Elem Expr
expr
}
)
type expr struct{ node }
func (*expr) aExpr() {}
type ChanDir uint
const (
_ ChanDir = iota
SendOnly
RecvOnly
)
// ----------------------------------------------------------------------------
// Statements
type (
Stmt interface {
Node
aStmt()
}
SimpleStmt interface {
Stmt
aSimpleStmt()
}
EmptyStmt struct {
simpleStmt
}
LabeledStmt struct {
Label *Name
Stmt Stmt
stmt
}
BlockStmt struct {
List []Stmt
Rbrace Pos
stmt
}
ExprStmt struct {
X Expr
simpleStmt
}
SendStmt struct {
Chan, Value Expr // Chan <- Value
simpleStmt
}
DeclStmt struct {
DeclList []Decl
stmt
}
AssignStmt struct {
Op Operator // 0 means no operation
Lhs, Rhs Expr // Rhs == ImplicitOne means Lhs++ (Op == Add) or Lhs-- (Op == Sub)
simpleStmt
}
BranchStmt struct {
Tok token // Break, Continue, Fallthrough, or Goto
Label *Name
// Target is the continuation of the control flow after executing
// the branch; it is computed by the parser if CheckBranches is set.
// Target is a *LabeledStmt for gotos, and a *SwitchStmt, *SelectStmt,
// or *ForStmt for breaks and continues, depending on the context of
// the branch. Target is not set for fallthroughs.
Target Stmt
stmt
}
CallStmt struct {
Tok token // Go or Defer
Call *CallExpr
stmt
}
ReturnStmt struct {
Results Expr // nil means no explicit return values
stmt
}
IfStmt struct {
Init SimpleStmt
Cond Expr
Then *BlockStmt
Else Stmt // either nil, *IfStmt, or *BlockStmt
stmt
}
ForStmt struct {
Init SimpleStmt // incl. *RangeClause
Cond Expr
Post SimpleStmt
Body *BlockStmt
stmt
}
SwitchStmt struct {
Init SimpleStmt
Tag Expr // incl. *TypeSwitchGuard
Body []*CaseClause
Rbrace Pos
stmt
}
SelectStmt struct {
Body []*CommClause
Rbrace Pos
stmt
}
)
type (
RangeClause struct {
Lhs Expr // nil means no Lhs = or Lhs :=
Def bool // means :=
X Expr // range X
simpleStmt
}
CaseClause struct {
Cases Expr // nil means default clause
Body []Stmt
Colon Pos
node
}
CommClause struct {
Comm SimpleStmt // send or receive stmt; nil means default clause
Body []Stmt
Colon Pos
node
}
)
type stmt struct{ node }
func (stmt) aStmt() {}
type simpleStmt struct {
stmt
}
func (simpleStmt) aSimpleStmt() {}
// ----------------------------------------------------------------------------
// Comments
// TODO(gri) Consider renaming to CommentPos, CommentPlacement, etc.
// Kind = Above doesn't make much sense.
type CommentKind uint
const (
Above CommentKind = iota
Below
Left
Right
)
type Comment struct {
Kind CommentKind
Text string
Next *Comment
}