fix case of variant which is valueless by exception #3347
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Thanks for the PR. Please add a test case to https://github.com/fmtlib/fmt/blob/master/test/std-test.cc. |
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@vitaut I have added the test case, and verified that it is working as intended. |
test/std-test.cc
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| @@ -95,6 +96,28 @@ TEST(std_test, optional) { | |||
| #endif | |||
| } | |||
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| // this struct exists only to force a variant to be | |||
| // valueless by exception | |||
| // NOLINTNEXTLINE | |||
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The purpose of the NOLINTNEXTLINE is to suppress clang-tidy warnings concerning the throws_on_move struct which is guaranteed to throw on move construction. I have removed it.
test/std-test.cc
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| template <> struct fmt::formatter<throws_on_move_t> : formatter<string_view> { | ||
| template <typename FormatContext> | ||
| auto format(const throws_on_move_t&, FormatContext& ctx) const { | ||
| string_view str{"<throws_on_move_t>"}; |
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We don't use brace initialization except for initializer lists, let's replace with normal initialization.
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My apologies, fixed.
test/std-test.cc
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| template <typename FormatContext> | ||
| auto format(const throws_on_move_t&, FormatContext& ctx) const { |
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This doesn't need to be a template, you can use format_context instead.
test/std-test.cc
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| @@ -126,6 +149,20 @@ TEST(std_test, variant) { | |||
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| volatile int i = 42; // Test compile error before GCC 11 described in #3068. | |||
| EXPECT_EQ(fmt::format("{}", i), "42"); | |||
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| using V2 = std::variant<std::monostate, throws_on_move_t>; | |||
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This alias is not needed, just use the variant type below.
test/std-test.cc
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| using V2 = std::variant<std::monostate, throws_on_move_t>; | ||
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| V2 v6{}; |
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{} is redundant, please remove.
test/std-test.cc
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| // this struct exists only to force a variant to be | ||
| // valueless by exception | ||
| // NOLINTNEXTLINE | ||
| struct throws_on_move_t { |
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_t suffix is normally used for aliases (typedefs), please remove.
test/std-test.cc
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| V2 v6{}; | ||
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| try { | ||
| throws_on_move_t thrower{}; |
test/std-test.cc
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| }; | ||
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| template <> struct fmt::formatter<throws_on_move> : formatter<string_view> { | ||
| auto format(const throws_on_move&, format_context& ctx) const { |
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This needs a return type for compatibility with older compilers.
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My apologies once again. I've fixed this.
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Almost there. Just one more issue on older compilers: https://www.internalfb.com/code/fbsource/[ae2a1f4ad0986b7c6686fa486466a9f6f47e9c05]/fbcode/thrift/compiler/test/fixtures/constants/gen-cpp2/module_constants.h?lines=140. |
I am unable to view this link. |
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That ought to fix it. |
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Thank you! |
This tiny repository contains a small bit of code which forces an
std::variantto be valueless by exception, and demonstrates that upstream fmtlib does not handle that case.My small change simply handles this case.