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cmd/compile: import/export of alias declarations
This CL completes support for alias declarations in the compiler. Also: - increased export format version - updated various comments For #16339. Fixes #17487. Change-Id: Ic6945fc44c0041771eaf9dcfe973f601d14de069 Reviewed-on: https://go-review.googlesource.com/32090 Run-TryBot: Robert Griesemer <gri@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Matthew Dempsky <mdempsky@google.com>
This commit is contained in:
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03d81b5ed9
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@ -9,10 +9,12 @@
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1) Export data encoding principles:
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The export data is a serialized description of the graph of exported
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"objects": constants, types, variables, and functions. In general,
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types - but also objects referred to from inlined function bodies -
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can be reexported and so we need to know which package they are coming
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from. Therefore, packages are also part of the export graph.
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"objects": constants, types, variables, and functions. Aliases may be
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directly reexported, and unaliased types may be indirectly reexported
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(as part of the type of a directly exorted object). More generally,
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objects referred to from inlined function bodies can be reexported.
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We need to know which package declares these reexported objects, and
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therefore packages are also part of the export graph.
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The roots of the graph are two lists of objects. The 1st list (phase 1,
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see Export) contains all objects that are exported at the package level.
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@ -30,9 +32,9 @@ function bodies. The format of this representation is compiler specific.
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The graph is serialized in in-order fashion, starting with the roots.
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Each object in the graph is serialized by writing its fields sequentially.
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If the field is a pointer to another object, that object is serialized,
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recursively. Otherwise the field is written. Non-pointer fields are all
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encoded as integer or string values.
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If the field is a pointer to another object, that object is serialized in
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place, recursively. Otherwise the field is written in place. Non-pointer
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fields are all encoded as integer or string values.
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Some objects (packages, types) may be referred to more than once. When
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reaching an object that was not serialized before, an integer _index_
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@ -43,7 +45,7 @@ If the object was already serialized, the encoding is simply the object
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index >= 0. An importer can trivially determine if an object needs to
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be read in for the first time (tag < 0) and entered into the respective
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object table, or if the object was seen already (index >= 0), in which
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case the index is used to look up the object in a table.
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case the index is used to look up the object in the respective table.
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Before exporting or importing, the type tables are populated with the
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predeclared types (int, string, error, unsafe.Pointer, etc.). This way
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@ -59,7 +61,7 @@ format. These strings are followed by version-specific encoding options.
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That format encoding is no longer used but is supported to avoid spurious
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errors when importing old installed package files.)
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The header is followed by the package object for the exported package,
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This header is followed by the package object for the exported package,
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two lists of objects, and the list of inlined function bodies.
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The encoding of objects is straight-forward: Constants, variables, and
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@ -69,6 +71,8 @@ same type was imported before via another import, the importer must use
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the previously imported type pointer so that we have exactly one version
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(i.e., one pointer) for each named type (and read but discard the current
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type encoding). Unnamed types simply encode their respective fields.
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Aliases are encoded starting with their name followed by the original
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(aliased) object.
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In the encoding, some lists start with the list length. Some lists are
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terminated with an end marker (usually for lists where we may not know
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@ -101,30 +105,8 @@ compatibility with both the last release of the compiler, and with the
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corresponding compiler at tip. That change is necessarily more involved,
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as it must switch based on the version number in the export data file.
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It is recommended to turn on debugFormat when working on format changes
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as it will help finding encoding/decoding inconsistencies quickly.
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Special care must be taken to update builtin.go when the export format
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changes: builtin.go contains the export data obtained by compiling the
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builtin/runtime.go and builtin/unsafe.go files; those compilations in
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turn depend on importing the data in builtin.go. Thus, when the export
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data format changes, the compiler must be able to import the data in
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builtin.go even if its format has not yet changed. Proceed in several
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steps as follows:
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- Change the exporter to use the new format, and use a different version
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string as well.
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- Update the importer accordingly, but accept both the old and the new
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format depending on the version string.
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- all.bash should pass at this point.
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- Run mkbuiltin.go: this will create a new builtin.go using the new
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export format.
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- go test -run Builtin should pass at this point.
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- Remove importer support for the old export format and (maybe) revert
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the version string again (it's only needed to mark the transition).
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- all.bash should still pass.
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Don't forget to set debugFormat to false.
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It is recommended to turn on debugFormat temporarily when working on format
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changes as it will help finding encoding/decoding inconsistencies quickly.
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*/
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package gc
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@ -158,7 +140,11 @@ const debugFormat = false // default: false
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const forceObjFileStability = true
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// Current export format version. Increase with each format change.
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const exportVersion = 2
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// 3: added aliasTag and export of aliases
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// 2: removed unused bool in ODCL export
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// 1: header format change (more regular), export package for _ struct fields
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// 0: Go1.7 encoding
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const exportVersion = 3
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// exportInlined enables the export of inlined function bodies and related
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// dependencies. The compiler should work w/o any loss of functionality with
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@ -364,6 +350,11 @@ func export(out *bufio.Writer, trace bool) int {
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if p.trace {
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p.tracef("\n")
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}
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if sym.Flags&SymAlias != 0 {
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Fatalf("exporter: unexpected alias %v in inlined function body", sym)
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}
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p.obj(sym)
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objcount++
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}
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@ -455,16 +446,44 @@ func unidealType(typ *Type, val Val) *Type {
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}
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func (p *exporter) obj(sym *Sym) {
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if sym.Flags&SymAlias != 0 {
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p.tag(aliasTag)
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p.pos(nil) // TODO(gri) fix position information
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// Aliases can only be exported from the package that
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// declares them (aliases to aliases are resolved to the
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// original object, and so are uses of aliases in inlined
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// exported function bodies). Thus, we only need the alias
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// name without package qualification.
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if sym.Pkg != localpkg {
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Fatalf("exporter: export of non-local alias: %v", sym)
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}
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p.string(sym.Name)
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sym = sym.Def.Sym // original object
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// fall through to export original
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// Multiple aliases to the same original will cause that
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// original to be exported multiple times (issue #17636).
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// TODO(gri) fix this
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}
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if sym != sym.Def.Sym {
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Fatalf("exporter: exported object %v is not original %v", sym, sym.Def.Sym)
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}
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if sym.Flags&SymAlias != 0 {
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Fatalf("exporter: original object %v marked as alias", sym)
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}
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// Exported objects may be from different packages because they
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// may be re-exported as depencies when exporting inlined function
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// bodies. Thus, exported object names must be fully qualified.
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// may be re-exported via an exported alias or as dependencies in
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// exported inlined function bodies. Thus, exported object names
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// must be fully qualified.
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//
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// TODO(gri) This can only happen if exportInlined is enabled
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// (default), and during phase 2 of object export. Objects exported
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// in phase 1 (compiler-indendepent objects) are by definition only
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// the objects from the current package and not pulled in via inlined
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// function bodies. In that case the package qualifier is not needed.
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// Possible space optimization.
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// (This can only happen for aliased objects or during phase 2
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// (exportInlined enabled) of object export. Unaliased Objects
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// exported in phase 1 (compiler-indendepent objects) are by
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// definition only the objects from the current package and not
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// pulled in via inlined function bodies. In that case the package
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// qualifier is not needed. Possible space optimization.)
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n := sym.Def
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switch n.Op {
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@ -1780,6 +1799,9 @@ const (
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stringTag
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nilTag
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unknownTag // not used by gc (only appears in packages with errors)
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// Aliases
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aliasTag
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)
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// Debugging support.
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@ -1815,6 +1837,9 @@ var tagString = [...]string{
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-stringTag: "string",
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-nilTag: "nil",
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-unknownTag: "unknown",
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// Aliases
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-aliasTag: "alias",
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}
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// untype returns the "pseudo" untyped type for a Ctype (import/export use only).
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@ -86,10 +86,10 @@ func Import(in *bufio.Reader) {
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// read version specific flags - extend as necessary
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switch p.version {
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// case 3:
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// case 4:
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// ...
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// fallthrough
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case 2, 1:
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case 3, 2, 1:
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p.debugFormat = p.rawStringln(p.rawByte()) == "debug"
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p.trackAllTypes = p.bool()
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p.posInfoFormat = p.bool()
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@ -307,26 +307,35 @@ func idealType(typ *Type) *Type {
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}
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func (p *importer) obj(tag int) {
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var alias *Sym
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if tag == aliasTag {
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p.pos()
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alias = importpkg.Lookup(p.string())
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alias.Flags |= SymAlias
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tag = p.tagOrIndex()
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}
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var sym *Sym
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switch tag {
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case constTag:
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p.pos()
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sym := p.qualifiedName()
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sym = p.qualifiedName()
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typ := p.typ()
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val := p.value(typ)
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importconst(sym, idealType(typ), nodlit(val))
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case typeTag:
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p.typ()
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sym = p.typ().Sym
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case varTag:
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p.pos()
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sym := p.qualifiedName()
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sym = p.qualifiedName()
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typ := p.typ()
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importvar(sym, typ)
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case funcTag:
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p.pos()
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sym := p.qualifiedName()
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sym = p.qualifiedName()
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params := p.paramList()
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result := p.paramList()
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@ -357,6 +366,11 @@ func (p *importer) obj(tag int) {
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default:
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formatErrorf("unexpected object (tag = %d)", tag)
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}
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if alias != nil {
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alias.Def = sym.Def
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importsym(alias, sym.Def.Op)
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}
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}
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func (p *importer) pos() {
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@ -63,6 +63,7 @@ const (
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SymSiggen
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SymAsm
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SymAlgGen
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SymAlias // alias, original is Sym.Def.Sym
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)
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// The Class of a variable/function describes the "storage class"
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@ -928,7 +928,7 @@ func mkpackage(pkgname string) {
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continue
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}
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if s.Def.Sym != s {
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if s.Def.Sym != s && s.Flags&SymAlias == 0 {
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// throw away top-level name left over
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// from previous import . "x"
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if s.Def.Name != nil && s.Def.Name.Pack != nil && !s.Def.Name.Pack.Used && nsyntaxerrors == 0 {
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@ -936,8 +936,6 @@ func mkpackage(pkgname string) {
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s.Def.Name.Pack.Used = true
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}
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// TODO(gri) This will also affect exported aliases.
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// Need to fix this.
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s.Def = nil
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continue
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}
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@ -174,7 +174,11 @@ func (p *noder) aliasDecl(decl *syntax.AliasDecl) {
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}
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pkg.Used = true
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// Resolve original entity
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orig := oldname(restrictlookup(qident.Sel.Value, pkg.Name.Pkg))
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if orig.Sym.Flags&SymAlias != 0 {
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Fatalf("original %v marked as alias", orig.Sym)
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}
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// An alias declaration must not refer to package unsafe.
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if orig.Sym.Pkg == unsafepkg {
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@ -222,16 +226,16 @@ func (p *noder) aliasDecl(decl *syntax.AliasDecl) {
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redeclare(asym, "in alias declaration")
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return
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}
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asym.Flags |= SymAlias
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asym.Def = orig
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asym.Block = block
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asym.Lastlineno = lineno
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if exportname(asym.Name) {
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yyerror("cannot export alias %v: not yet implemented", asym)
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// TODO(gri) newname(asym) is only needed to satisfy exportsym
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// (and indirectly, exportlist). We should be able to just
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// collect the Syms, eventually.
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// exportsym(newname(asym))
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exportsym(newname(asym))
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}
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}
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|
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@ -98,10 +98,10 @@ func BImportData(fset *token.FileSet, imports map[string]*types.Package, data []
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// read version specific flags - extend as necessary
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switch p.version {
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// case 3:
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// case 4:
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// ...
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// fallthrough
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case 2, 1:
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case 3, 2, 1:
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p.debugFormat = p.rawStringln(p.rawByte()) == "debug"
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p.trackAllTypes = p.int() != 0
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p.posInfoFormat = p.int() != 0
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|
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@ -50,7 +50,7 @@ func f => before.f // ERROR "before is not a package"
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var v => after.m // ERROR "after is not a package"
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func f => after.m // ERROR "after is not a package"
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// TODO(gri) fix error printing - should not print a qualified identifier...
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// TODO(gri) fix error printing - should print correct qualified identifier...
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var _ => Default.ARCH // ERROR "build.Default is not a package"
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// aliases may not refer to package unsafe
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@ -77,11 +77,11 @@ func sin1 => math.Pi // ERROR "math.Pi is not a function"
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// alias reference to a package marks package as used
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func _ => fmt.Println
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// TODO(gri) aliased cannot be exported yet - fix this
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const Pi => math.Pi // ERROR "cannot export alias Pi"
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type Writer => io.Writer // ERROR "cannot export alias Writer"
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var Def => build.Default // ERROR "cannot export alias Def"
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func Sin => math.Sin // ERROR "cannot export alias Sin"
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// re-exported aliases
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const Pi => math.Pi
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type Writer => io.Writer
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var Def => build.Default
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func Sin => math.Sin
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// type aliases denote identical types
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type myPackage => build.Package
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|
|
54
test/alias3.dir/a.go
Normal file
54
test/alias3.dir/a.go
Normal file
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@ -0,0 +1,54 @@
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// Copyright 2016 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package a
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import (
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"bytes"
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"go/build"
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"io"
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"math"
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)
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func F(c *build.Context, w io.Writer) {}
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func Inlined() bool { var w Writer; return w == nil }
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func Check() {
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if Pi != math.Pi {
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panic(0)
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}
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var w Writer
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F(new(Context), w)
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F(new(build.Context), bytes.NewBuffer(nil))
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if &Default != &build.Default {
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panic(1)
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}
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if Sin(1) != math.Sin(1) {
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panic(2)
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}
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var _ *LimitedReader = new(LimitedReader2)
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}
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// export aliases
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const Pi => math.Pi
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type (
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Context => build.Context // not an interface
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Writer => io.Writer // interface
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)
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// different aliases may refer to the same original
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type LimitedReader => io.LimitedReader
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type LimitedReader2 => io.LimitedReader
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var Default => build.Default
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var Default2 => build.Default
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func Sin => math.Sin
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func Sin2 => math.Sin
|
61
test/alias3.dir/b.go
Normal file
61
test/alias3.dir/b.go
Normal file
|
@ -0,0 +1,61 @@
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// Copyright 2016 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package b
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import (
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"./a"
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"bytes"
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"go/build"
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"io"
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"math"
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)
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func F => a.F
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func Inlined => a.Inlined
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var _ func(*Context, io.Writer) = a.F
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// check aliases
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func Check() {
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if Pi != math.Pi {
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panic(0)
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}
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var w Writer
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a.F(new(Context), w)
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F(new(build.Context), bytes.NewBuffer(nil))
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if !Inlined() {
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panic(1)
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}
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|
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if &Default != &build.Default {
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panic(2)
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}
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if Sin(1) != math.Sin(1) {
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panic(3)
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}
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|
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var _ *LimitedReader = new(LimitedReader2)
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}
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|
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// re-export aliases
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const Pi => a.Pi
|
||||
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type (
|
||||
Context => a.Context // not an interface
|
||||
Writer => a.Writer // interface
|
||||
)
|
||||
|
||||
// different aliases may refer to the same original
|
||||
type LimitedReader => a.LimitedReader
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||||
type LimitedReader2 => a.LimitedReader2
|
||||
|
||||
var Default => a.Default
|
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var Default2 => a.Default2
|
||||
|
||||
func Sin => a.Sin
|
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func Sin2 => a.Sin
|
66
test/alias3.dir/c.go
Normal file
66
test/alias3.dir/c.go
Normal file
|
@ -0,0 +1,66 @@
|
|||
// 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 main
|
||||
|
||||
import (
|
||||
"./a"
|
||||
"./b"
|
||||
"bytes"
|
||||
"go/build"
|
||||
"math"
|
||||
)
|
||||
|
||||
func f => b.F
|
||||
func inlined => b.Inlined
|
||||
|
||||
var _ func(*context, a.Writer) = f
|
||||
|
||||
func Check() {
|
||||
if pi != math.Pi {
|
||||
panic(0)
|
||||
}
|
||||
|
||||
var w writer
|
||||
b.F(new(context), w)
|
||||
f(new(build.Context), bytes.NewBuffer(nil))
|
||||
|
||||
if !inlined() {
|
||||
panic(1)
|
||||
}
|
||||
|
||||
if &default_ != &build.Default {
|
||||
panic(2)
|
||||
}
|
||||
|
||||
if sin(1) != math.Sin(1) {
|
||||
panic(3)
|
||||
}
|
||||
|
||||
var _ *limitedReader = new(limitedReader2)
|
||||
}
|
||||
|
||||
// local aliases
|
||||
const pi => b.Pi
|
||||
|
||||
type (
|
||||
context => b.Context // not an interface
|
||||
writer => b.Writer // interface
|
||||
)
|
||||
|
||||
// different aliases may refer to the same original
|
||||
type limitedReader => b.LimitedReader
|
||||
type limitedReader2 => b.LimitedReader2
|
||||
|
||||
var default_ => b.Default
|
||||
var default2 => b.Default2
|
||||
|
||||
func sin => b.Sin
|
||||
func sin2 => b.Sin
|
||||
|
||||
func main() {
|
||||
a.Check()
|
||||
b.Check()
|
||||
Check()
|
||||
}
|
7
test/alias3.go
Normal file
7
test/alias3.go
Normal file
|
@ -0,0 +1,7 @@
|
|||
// rundir
|
||||
|
||||
// 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 ignored
|
Loading…
Reference in a new issue