Fix C++20 build: don't name constructors with a template-id#77
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darrylabbate wants to merge 1 commit into
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Fix C++20 build: don't name constructors with a template-id#77darrylabbate wants to merge 1 commit into
darrylabbate wants to merge 1 commit into
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GCC 15 (the default compiler on Ubuntu 26.04) and other modern C++20
toolchains reject a template-id as a constructor declarator:
error: template-id not allowed for constructor in C++20
[-Werror=template-id-cdtor]
The DEFINE_INHERITED macro expands its first argument into the
constructor declarator (`CLASS() { ... }`). For the templated benchmark
classes, that argument was the full template-id, e.g.
DEFINE_INHERITED(GLUE_TYPENAME(OriginalBenchmark<bs, fn_ptr>), bs);
which expands to `OriginalBenchmark<bs, fn_ptr>() { ... }` -- a
constructor named with a template-id, forbidden under C++20. Because
IMB's Makefile builds with -Werror, this breaks the whole build on
GCC 15.
Pass the bare class name (the injected-class-name) instead of the
template-id at the three templated call sites (OriginalBenchmark,
BenchmarkMT, HaloBenchmark). Inside a class template the
injected-class-name denotes the current instantiation, so both the
`new CLASS` expression and the `CLASS()` constructor declarator remain
correct, while the constructor is no longer spelled with a template-id.
The non-templated call sites already pass a plain class name and are
unchanged.
Builds clean with GCC 15.2 (-Wall -Wextra -Werror, default C++17 and
under -std=c++20) with no other changes.
Signed-off-by: Darryl Abbate <drl@amazon.com>
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GCC 15 (the default compiler on Ubuntu 26.04) and other modern C++20 toolchains reject a template-id as a constructor declarator:
The DEFINE_INHERITED macro expands its first argument into the constructor declarator (
CLASS() { ... }). For the templated benchmark classes, that argument was the full template-id, e.g.which expands to
OriginalBenchmark<bs, fn_ptr>() { ... }-- a constructor named with a template-id, forbidden under C++20. Because IMB's Makefile builds with -Werror, this breaks the whole build on GCC 15.Pass the bare class name (the injected-class-name) instead of the template-id at the three templated call sites (OriginalBenchmark, BenchmarkMT, HaloBenchmark). Inside a class template the injected-class-name denotes the current instantiation, so both the
new CLASSexpression and theCLASS()constructor declarator remain correct, while the constructor is no longer spelled with a template-id. The non-templated call sites already pass a plain class name and are unchanged.Builds clean with GCC 15.2 (-Wall -Wextra -Werror, default C++17 and under -std=c++20) with no other changes.