const variables internal linkage | Together C & C++ | Page 1

round marlin Oct 24, 2025, 4:48 PM

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why do const variables have internal linkage?

outer dragonBOT Oct 24, 2025, 4:48 PM

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pallid wharf Oct 24, 2025, 11:46 PM

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So you can define constants in header files without violating ODR.

When you include that header file in many .cpp files, it’s local to the current translation unit (basically, the .cpp file thats being compiled + all its included headers)
Afaik C++17(11?14?) introduces a new meaning for inline that indicates to the linker that an identifier is allowed to be defined in multiple translation units and that the definition will be the same everywhere.

Const variables are implicitly inline

unborn jetty Oct 25, 2025, 2:38 AM

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Internal linkage and inline refer to different concepts. Internal linkage refers to stuff like static globals

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Anyway, it's just too prevent bugs, and it's not like you would need external linkage of a read only variable.

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