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Fix MSVC C4702 warning caused by JSON_HEDLEY_NO_RETURN on get_elements()

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PR #5250 annotated wide_string_input_adapter::get_elements<T>() with
JSON_HEDLEY_NO_RETURN (it unconditionally throws). On MSVC this expands to
__declspec(noreturn), and MSVC correctly determined that the code following
its call in binary_reader.hpp is unreachable for that instantiation, firing
C4702 under /W4 /WX in the msvc, msvc-vs2026, and msvc-arm64 Debug jobs.

Clang doesn't flag this case, so the Docker verification for #5250 (which
only checked Clang -Weverything) didn't catch it.

This is the same warning class already tolerated for Release builds since
PR #5216, where MSVC's optimizer independently found the same dead code
after /Od was removed. Extend that existing /wd4702 suppression to Debug
builds too, instead of reverting the noreturn annotation.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
This commit is contained in:
Niels Lohmann
2026-07-09 06:56:03 +02:00
parent 4c5b2b0666
commit d4e024be11
1 changed files with 5 additions and 1 deletions
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tests/CMakeLists.txt
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@@ -68,7 +68,11 @@ target_compile_options(test_main PUBLIC
# Disable warning C4566: character represented by universal-character-name '\uFF01' # Disable warning C4566: character represented by universal-character-name '\uFF01'
# cannot be represented in the current code page (1252) # cannot be represented in the current code page (1252)
# Disable warning C4996: 'nlohmann::basic_json<...>::operator <<': was declared deprecated # Disable warning C4996: 'nlohmann::basic_json<...>::operator <<': was declared deprecated
$<$<CXX_COMPILER_ID:MSVC>:/W4;/wd4566;/wd4996;$<$<CONFIG:Release>:/wd4702>> # Disable warning C4702: unreachable code; wide_string_input_adapter::get_elements()
# is annotated JSON_HEDLEY_NO_RETURN (it always throws), which
# makes MSVC flag the code following its call in binary_reader.hpp
# as unreachable for that instantiation, in both Debug and Release
$<$<CXX_COMPILER_ID:MSVC>:/W4;/wd4566;/wd4996;/wd4702>
# https://github.com/nlohmann/json/issues/1114 # https://github.com/nlohmann/json/issues/1114
$<$<CXX_COMPILER_ID:MSVC>:/bigobj> $<$<BOOL:${MINGW}>:-Wa,-mbig-obj> $<$<CXX_COMPILER_ID:MSVC>:/bigobj> $<$<BOOL:${MINGW}>:-Wa,-mbig-obj>