#-Wtemplates warning triggered

14 messages · Page 1 of 1 (latest)

lean stirrup
# 
#include <iostream>

template <typename T> auto sum(T arg) -> T { return arg; }

template <typename T, typename... Args> auto sum(T start, Args... args) -> T
{
    return start + sum(args...);
}

auto main() -> int
{
    std::cout << sum(1, 2, 3, 4) << '\n';
    return 0;
}

So I've been messing around with templates and variadic arguments and found a warning being triggered...

$make run
mkdir -p build
cmake -S . -B build -G Ninja \
        -DCMAKE_CXX_COMPILER=g++ \
        -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
-- Configuring done (0.0s)
-- Generating done (0.0s)
-- Build files have been written to: /home/amogus/c/l/cpp/build
ln -sf build/compile_commands.json compile_commands.json
ninja -C build
ninja: Entering directory `build'
[1/2] Building CXX object CMakeFiles/app.dir/src/main.cpp.o
/home/amogus/c/l/cpp/src/main.cpp:3:42: warning: template ‘T sum(T)’ declared [-Wtemplates]
    3 | template <typename T> auto sum(T arg) -> T { return arg; }
      |                                          ^
/home/amogus/c/l/cpp/src/main.cpp:4:76: warning: template ‘T sum(T, Args ...)’ declared [-Wtemplates]
    4 | template <typename T, typename... Args> auto sum(T start, Args... args) -> T
      |                                                                            ^
[2/2] Linking CXX executable app
./build/app
10

I know I can always turn off the warnings, but I'm curious as to why the flag thinks lines 3 and 4 are warning-worthy

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#

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left anchor
#

doesn't -Wtemplates simply warn on every declaration of a template?

#

if so, it doesn't seem very useful

#

;compile -Wtemplates ```cpp
template<typename> int x;
int main() {}

green crownBOT
#
Compiler Output
<source>:1:24: warning: template 'x' declared [-Wtemplates]
    1 | template<typename> int x;
      |                        ^
eczbek | 21ms | c++ | x86-64 gcc 15.2 | godbolt.org
left anchor
#

yeah

silent rain
# 
 -Wtemplates (C++ and Objective-C++ only)
     Warn when a primary template declaration is encountered.  Some coding rules disallow
     templates, and this may be used to enforce that rule.  The warning is inactive in‐
     side a system header file, such as the STL, so one can still use the STL.  One may
     also instantiate or specialize templates.

:>

lean stirrup
#

well time to remove it then

final forumBOT
# final forum

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timber silo
#

-Wcpp when

#

warning: C++ code detected [-Wcpp]

left anchor
#

LOL

silent rain