1 Vendoring in std and cmd
4 The Go command maintains copies of external packages needed by the
5 standard library in the src/vendor and src/cmd/vendor directories.
7 In GOPATH mode, imports of vendored packages are resolved to these
8 directories following normal vendor directory logic
9 (see golang.org/s/go15vendor).
11 In module mode, std and cmd are modules (defined in src/go.mod and
12 src/cmd/go.mod). When a package outside std or cmd is imported
13 by a package inside std or cmd, the import path is interpreted
14 as if it had a "vendor/" prefix. For example, within "crypto/tls",
15 an import of "golang.org/x/crypto/cryptobyte" resolves to
16 "vendor/golang.org/x/crypto/cryptobyte". When a package with the
17 same path is imported from a package outside std or cmd, it will
18 be resolved normally. Consequently, a binary may be built with two
19 copies of a package at different versions if the package is
20 imported normally and vendored by the standard library.
22 Vendored packages are internally renamed with a "vendor/" prefix
23 to preserve the invariant that all packages have distinct paths.
24 This is necessary to avoid compiler and linker conflicts. Adding
25 a "vendor/" prefix also maintains the invariant that standard
26 library packages begin with a dotless path element.
28 The module requirements of std and cmd do not influence version
29 selection in other modules. They are only considered when running
30 module commands like 'go get' and 'go mod vendor' from a directory
31 in GOROOT/src.
33 Maintaining vendor directories
36 Before updating vendor directories, ensure that module mode is enabled.
37 Make sure GO111MODULE=off is not set ('on' or 'auto' should work).
39 Requirements may be added, updated, and removed with 'go get'.
40 The vendor directory may be updated with 'go mod vendor'.
41 A typical sequence might be:
43 cd src
44 go get -d golang.org/x/net@latest
45 go mod tidy
46 go mod vendor
48 Use caution when passing '-u' to 'go get'. The '-u' flag updates
49 modules providing all transitively imported packages, not only
50 the module providing the target package.
52 Note that 'go mod vendor' only copies packages that are transitively
53 imported by packages in the current module. If a new package is needed,
54 it should be imported before running 'go mod vendor'.
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