Why Are Slashes and Dots Used in C Function Names and Prototypes in the Go Source Tree?

Slashes and Dots in Function Names and Prototypes

In the provided C code snippet from Go's source tree, you've noticed the use of slashes (/) and dots (·) in function names and prototypes, which raises questions about their validity and meaning.

Firstly, it's important to note that the file is compiled using Go's internal C compiler, which originates from the Plan 9 C compiler. This compiler allows for the use of UTF-8 characters in identifiers, extending the C standard.

In particular, the middot character (·) is treated specially. It is translated to a regular dot (.) in object files during compilation. This dot is then interpreted as a namespace separator character by the Go linker.

For example, the function prototype void runtime∕race·Read(int32 goid, void *addr, void *pc); would be translated to the object file symbol T runtime.race.Read.

Regarding the slashes, they are also translated by the internal compiler to regular forward slashes (/). Hence, foo∕baz becomes foo/baz.

The "·" and "/" characters in the function names allow for the creation of nested namespaces. In the Go language suite, the empty namespace (denoted by "") can be used as a placeholder. It acts like a root namespace and can be dynamically substituted with a real namespace during the linking process.

This mechanism is employed in the import statement, where an empty namespace is specified in the import path. During linking, the empty namespace is replaced with the actual path to the imported package. For instance, import examp "path/to/package/example" would translate ".Bar1()" to "path/to/package/example.Bar1()".

In conclusion, the slashes and dots (·) in the provided C code are used for creating nested namespaces and are translated to standard C dot and slash characters during compilation. This allows for a flexible and dynamic namespace management in the Go language suite.

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