Text file src/README.vendor

     1  Vendoring in std and cmd
     2  ========================
     3  
     4  The Go command maintains copies of external packages needed by the
     5  standard library in the src/vendor and src/cmd/vendor directories.
     6  
     7  There are two modules, std and cmd, defined in src/go.mod and
     8  src/cmd/go.mod. When a package outside std or cmd is imported
     9  by a package inside std or cmd, the import path is interpreted
    10  as if it had a "vendor/" prefix. For example, within "crypto/tls",
    11  an import of "golang.org/x/crypto/cryptobyte" resolves to
    12  "vendor/golang.org/x/crypto/cryptobyte". When a package with the
    13  same path is imported from a package outside std or cmd, it will
    14  be resolved normally. Consequently, a binary may be built with two
    15  copies of a package at different versions if the package is
    16  imported normally and vendored by the standard library.
    17  
    18  Vendored packages are internally renamed with a "vendor/" prefix
    19  to preserve the invariant that all packages have distinct paths.
    20  This is necessary to avoid compiler and linker conflicts. Adding
    21  a "vendor/" prefix also maintains the invariant that standard
    22  library packages begin with a dotless path element.
    23  
    24  The module requirements of std and cmd do not influence version
    25  selection in other modules. They are only considered when running
    26  module commands like 'go get' and 'go mod vendor' from a directory
    27  in GOROOT/src.
    28  
    29  Maintaining vendor directories
    30  ==============================
    31  
    32  Before updating vendor directories, ensure that module mode is enabled.
    33  Make sure that GO111MODULE is not set in the environment, or that it is
    34  set to 'on' or 'auto'.
    35  
    36  Requirements may be added, updated, and removed with 'go get'.
    37  The vendor directory may be updated with 'go mod vendor'.
    38  A typical sequence might be:
    39  
    40      cd src
    41      go get golang.org/x/net@latest
    42      go mod tidy
    43      go mod vendor
    44  
    45  Use caution when passing '-u' to 'go get'. The '-u' flag updates
    46  modules providing all transitively imported packages, not only
    47  the module providing the target package.
    48  
    49  Note that 'go mod vendor' only copies packages that are transitively
    50  imported by packages in the current module. If a new package is needed,
    51  it should be imported before running 'go mod vendor'.
    52  

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