fix: add missing backslash in macro definition

[Joseph-Edwards]

Description

This PR adds a missing backslash in one of the definitions of CATCH_INTERNAL_SUPPRESS_ZERO_VARIADIC_WARNINGS. This typo was introduced in v3.8.1. The inclusion of this backslash fixes as issue we were facing in libsemigroups/libsemigroups#931 upon updating from v3.8.0 to v3.13.0.

Minimal reproducible example

The following is a minimal reproducible example that demonstrates the error being thrown in our CI pipeline:

Contents of test.cpp:

#include <string>  // for string
#include <vector>  // for vector

#pragma GCC diagnostic push
#include "catch_amalgamated.hpp"  // for TEMPLATE_TEST_CASE
#pragma GCC diagnostic pop

TEMPLATE_TEST_CASE("example", "[quick]", int, std::string) {
  std::vector<TestType> v(5);
  REQUIRE(v.size() == 5);
}

Compile command:

> clang++ -Werror -Wgnu-zero-variadic-macro-arguments -std=gnu++17 test.cpp catch_amalgamated.cpp -o test

File structure:

.
├── catch_amalgamated.cpp
├── catch_amalgamated.hpp
└── test.cpp

Expected output:
File compiles (which is achieved upon applying the changes in this PR).

Actual output:

test.cpp:8:1: error: must specify at least one argument for '...' parameter of variadic macro [-Werror,-Wgnu-zero-variadic-macro-arguments]
    8 | TEMPLATE_TEST_CASE("example", "[quick]", int, std::string) {
      | ^
./catch_amalgamated.hpp:7021:39: note: expanded from macro 'TEMPLATE_TEST_CASE'
 7021 |     #define TEMPLATE_TEST_CASE( ... ) INTERNAL_CATCH_TEMPLATE_TEST_CASE( __VA_ARGS__ )
      |                                       ^
./catch_amalgamated.hpp:6734:9: note: expanded from macro 'INTERNAL_CATCH_TEMPLATE_TEST_CASE'
 6734 |         INTERNAL_CATCH_TEMPLATE_TEST_CASE_2( INTERNAL_CATCH_UNIQUE_NAME( CATCH2_INTERNAL_TEMPLATE_TEST_ ), INTERNAL_CATCH_UNIQUE_NAME( CATCH2_INTERNAL_TEMPLATE_TEST_ ), Name, Tags, typename TestType, __VA_ARGS__ )
      |         ^
./catch_amalgamated.hpp:6712:13: note: expanded from macro 'INTERNAL_CATCH_TEMPLATE_TEST_CASE_2'
 6712 |             INTERNAL_CATCH_NTTP_GEN(INTERNAL_CATCH_REMOVE_PARENS(Signature))\
      |             ^
./catch_amalgamated.hpp:6625:465: note: expanded from macro 'INTERNAL_CATCH_NTTP_GEN'
 6625 | #define INTERNAL_CATCH_NTTP_GEN(...) INTERNAL_CATCH_VA_NARGS_IMPL(__VA_ARGS__, INTERNAL_CATCH_NTTP_1(__VA_ARGS__), INTERNAL_CATCH_NTTP_1(__VA_ARGS__), INTERNAL_CATCH_NTTP_1(__VA_ARGS__), INTERNAL_CATCH_NTTP_1(__VA_ARGS__), INTERNAL_CATCH_NTTP_1(__VA_ARGS__), INTERNAL_CATCH_NTTP_1( __VA_ARGS__), INTERNAL_CATCH_NTTP_1( __VA_ARGS__), INTERNAL_CATCH_NTTP_1( __VA_ARGS__), INTERNAL_CATCH_NTTP_1( __VA_ARGS__),INTERNAL_CATCH_NTTP_1( __VA_ARGS__), INTERNAL_CATCH_NTTP_0)
      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 ^
./catch_amalgamated.hpp:6508:9: note: macro 'INTERNAL_CATCH_VA_NARGS_IMPL' defined here
 6508 | #define INTEclang++ --version
Ubuntu clang version 18.1.3 (1ubuntu1)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/binRNAL_CATCH_VA_NARGS_IMPL(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, N, ...) N
      |         ^
test.cpp:8:1: error: must specify at least one argument for '...' parameter of variadic macro [-Werror,-Wgnu-zero-variadic-macro-arguments]
    8 | TEMPLATE_TEST_CASE("example", "[quick]", int, std::string) {
      | ^
./catch_amalgamated.hpp:7021:39: note: expanded from macro 'TEMPLATE_TEST_CASE'
 7021 |     #define TEMPLATE_TEST_CASE( ... ) INTERNAL_CATCH_TEMPLATE_TEST_CASE( __VA_ARGS__ )
      |                                       ^
./catch_amalgamated.hpp:6734:9: note: expanded from macro 'INTERNAL_CATCH_TEMPLATE_TEST_CASE'
 6734 |         INTERNAL_CATCH_TEMPLATE_TEST_CASE_2( INTERNAL_CATCH_UNIQUE_NAME( CATCH2_INTERNAL_TEMPLATE_TEST_ ), INTERNAL_CATCH_UNIQUE_NAME( CATCH2_INTERNAL_TEMPLATE_TEST_ ), Name, Tags, typename TestType, __VA_ARGS__ )
      |         ^
./catch_amalgamated.hpp:6724:22: note: expanded from macro 'INTERNAL_CATCH_TEMPLATE_TEST_CASE_2'
 6724 |             TestName<INTERNAL_CATCH_MAKE_TYPE_LISTS_FROM_TYPES(__VA_ARGS__)>();\
      |                      ^
./catch_amalgamated.hpp:6494:20: note: expanded from macro 'INTERNAL_CATCH_MAKE_TYPE_LISTS_FROM_TYPES'
 6494 |     CATCH_REC_LIST(INTERNAL_CATCH_MAKE_TYPE_LIST,__VA_ARGS__)
      |                    ^
./catch_amalgamated.hpp:6508:9: note: macro 'INTERNAL_CATCH_VA_NARGS_IMPL' defined here
 6508 | #define INTERNAL_CATCH_VA_NARGS_IMPL(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, N, ...) N
      |         ^
test.cpp:8:1: error: must specify at least one argument for '...' parameter of variadic macro [-Werror,-Wgnu-zero-variadic-macro-arguments]
    8 | TEMPLATE_TEST_CASE("example", "[quick]", int, std::string) {
      | ^
./catch_amalgamated.hpp:7021:39: note: expanded from macro 'TEMPLATE_TEST_CASE'
 7021 |     #define TEMPLATE_TEST_CASE( ... ) INTERNAL_CATCH_TEMPLATE_TEST_CASE( __VA_ARGS__ )
      |                                       ^
./catch_amalgamated.hpp:6734:9: note: expanded from macro 'INTERNAL_CATCH_TEMPLATE_TEST_CASE'
 6734 |         INTERNAL_CATCH_TEMPLATE_TEST_CASE_2( INTERNAL_CATCH_UNIQUE_NAME( CATCH2_INTERNAL_TEMPLATE_TEST_ ), INTERNAL_CATCH_UNIQUE_NAME( CATCH2_INTERNAL_TEMPLATE_TEST_ ), Name, Tags, typename TestType, __VA_ARGS__ )
      |         ^
./catch_amalgamated.hpp:6724:22: note: expanded from macro 'INTERNAL_CATCH_TEMPLATE_TEST_CASE_2'
 6724 |             TestName<INTERNAL_CATCH_MAKE_TYPE_LISTS_FROM_TYPES(__VA_ARGS__)>();\
      |                      ^
./catch_amalgamated.hpp:6494:20: note: expanded from macro 'INTERNAL_CATCH_MAKE_TYPE_LISTS_FROM_TYPES'
 6494 |     CATCH_REC_LIST(INTERNAL_CATCH_MAKE_TYPE_LIST,__VA_ARGS__)
      |                    ^
./catch_amalgamated.hpp:6508:9: note: macro 'INTERNAL_CATCH_VA_NARGS_IMPL' defined here
 6508 | #define INTERNAL_CATCH_VA_NARGS_IMPL(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, N, ...) N
      |         ^
3 errors generated.

Other useful information:

> clang++ --version
Ubuntu clang version 18.1.3 (1ubuntu1)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin

Testing

I have tested locally that the changes in this PR fix the errors outlined above; however, I wasn't sure how to add tests to the Catch2 test suite that illustrate this. I'd be happy to add tests here with a little bit of guidance!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.37%. Comparing base (ccc49ba) to head (985db5c).
⚠️ Report is 1 commits behind head on devel.

Additional details and impacted files

@@            Coverage Diff             @@
##            devel    #3085      +/-   ##
==========================================
+ Coverage   91.34%   91.37%   +0.03%     
==========================================
  Files         204      204              
  Lines        8899     8899              
==========================================
+ Hits         8128     8131       +3     
+ Misses        771      768       -3     

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[horenmar]

Thanks.

I don't think you need to add tests for this change. It would be nice to have tests that the various warning suppressions are getting picked up properly, but I don't think it would be worth the effort to implement them; this is the first time I remember seeing the formatting of the suppression macros get broken like this.