https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111769
Bug ID: 111769
Summary: Annotate function definitions and calls to facilitate
link-time checking
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: david at westcontrol dot com
Target Milestone: ---
This is an enhancement idea, rather than a bug, and would require linker
support as well as compiler support.
In C, it is possible to define a function with one set of parameters (number
and type) in one translation unit, and declare and use it with a different set
in a different translation unit. This is undefined behaviour, and generally a
really bad idea, but it can't be spotted by the toolchain unless you use LTO.
In C++, you don't see the same effect as different name mangling would result
in linker failures.
Would it be possible for the C compiler, when emitting an external linkage
function definition and the use (or possibly declaration) of a function (for
calling or taking its address), to add a directive or debug info section entry
giving the function type in active use? These could then be checked at link
time, even without LTO, to catch mismatches.
My suggestion would be to use the existing C++ name-mangling scheme to encode
the function types. Thus the declaration and definition of "int square(int
num)" would be annotated with a note that the function "square" has signature
"_Z6squarei".
