c - Why is "symbol lookup error" not caught at compile-time? -


i'm updating old code, , accidentally left macro inside that's no longer defined:

// "detail" not defined anywhere if (detail ("notebook")) {     // ... }

the code still compiles , links (its .so library), when loaded get:

gtk3-widget-factory: symbol lookup error: /usr/lib/gtk-3.0/3.0.0/ theming-engines/libmurrine.so: undefined symbol: detail

why isn't caught @ compile time? guess c sees detail without definition , assumes function int -> int , right? there way make compiler (gcc) more strict , complain @ compile time? don't think i'm directly using symbols without definition in source or header files.

your analysis correct: detail treated implicitly-defined function.

from gcc manual:

-wimplicit-function-declaration (c , objective-c only)

give warning whenever function used before being declared. in c99 mode (-std=c99 or -std=gnu99), warning enabled default , made error -pedantic-errors. warning enabled -wall.

additionally, @jonathan leffler points out in comments:

also, in versions of gcc, it's error -werror=implicit-function-declaration (and other explicit warning option). warnings can converted errors -werror.


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