Add snprintf fallback for float/double formatting (IAR support)#2
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…ut floating std::to_chars
Integer std::to_chars is universally available, but the floating-point
overloads are not implemented everywhere: IAR's libc++ (bxarm) ships
std::to_chars(float/double) as deleted functions, so StringBuilder.cpp
fails to compile there even when no float/double is ever formatted.
Guard the four floating-point formatters (append/prepend for float and
double) behind NFX_STRINGBUILDER_HAS_FLOAT_TO_CHARS, which defaults to 0
under IAR and 1 elsewhere, and can be overridden by the consumer. When
disabled, format via std::snprintf("%.*g", max_digits10, ...) into a
stack buffer and reuse the existing append/prepend(string_view) path.
Integer formatting is untouched.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Jul 7, 2026
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Jul 7, 2026
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Description
Guards the four floating-point
StringBuilderformatters (append/prependforfloatanddouble) behind a newNFX_STRINGBUILDER_HAS_FLOAT_TO_CHARSmacro. When floatingstd::to_charsis unavailable, they fall back tostd::snprintf("%.*g", max_digits10, ...)into a stack buffer and reuse the existingappend/prepend(std::string_view)path. Integer formatting is unchanged.The macro defaults to
0under IAR (__IAR_SYSTEMS_ICC__) and1elsewhere, and can be overridden by the consumer before including the header.Motivation and Context
Integer
std::to_charsis universally available, but the floating-point overloads are not: IAR's libc++ (bxarm) shipsstd::to_chars(float/double)as deleted functions. BecauseStringBuilder.cppinstantiates everyappend/prependoverload, the library currently fails to cross-compile under IAR even when the consumer never formats a float or double.This came up integrating nfx-stringbuilder into an embedded (arm-cm7-iar) firmware build for MQTT topic construction, which only ever appends integers and string literals.
How Has This Been Tested?
StringBuilder.cpp) with IAR bxarm 9.50.2 for arm-cm7 — fails without this change (deletedstd::to_chars), links cleanly with it.std::to_charspath.🤖 Generated with Claude Code