From 9a11bb6f534c943cbe56a6632c59aa8a335cb69d Mon Sep 17 00:00:00 2001
From: Christopher Wellons <wellons@nullprogram.com>
Date: Fri, 10 Jul 2026 20:24:08 -0400
Subject: [PATCH] crt: __MINGW_IMP_SYMBOL for _strtof_l and _wcstof_l

These functions are static emulations present in every libmsvcr*.a,
but the headers declare them dllimport (_CRTIMP), so callers reference
__imp__strtof_l and __imp__wcstof_l, which nothing defines, and the
link fails. Define fake import pointers alongside the definitions, as
already done for other statically-emulated functions such as
__acrt_iob_func and _initialize_onexit_table.

The _strtof_l half was merged upstream after v14.0.0 as 373c7dd0
("crt: Add missing __MINGW_IMP_SYMBOL for _strtof_l()"). The
_wcstof_l half is the same fix for the wide variant, which remains
broken upstream.
---
 Dockerfile                   |  3 +++
 src/mingw-imp-strtof_l.patch | 30 ++++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+)
 create mode 100644 src/mingw-imp-strtof_l.patch

diff --git a/Dockerfile b/Dockerfile
index a8fbb5c..308c628 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -251,6 +251,9 @@ RUN /dl/binutils/configure \
 # https://sourceforge.net/p/mingw-w64/bugs/821/
 RUN sed -i /OpenThreadToken/d /dl/mingw/mingw-w64-crt/lib32/kernel32.def
 
+COPY src/mingw-*.patch $PREFIX/src/
+RUN cat $PREFIX/src/mingw-*.patch | patch -d/dl/mingw -p1
+
 WORKDIR /x-mingw-headers
 RUN printf '#include <crtdefs.h>\n#if __has_include_next(<stddef.h>)\n#include_next <stddef.h>\n#endif\n' \
       >/dl/mingw/mingw-w64-headers/crt/stddef.h \
diff --git a/src/mingw-imp-strtof_l.patch b/src/mingw-imp-strtof_l.patch
new file mode 100644
index 0000000..6394937
--- /dev/null
+++ b/src/mingw-imp-strtof_l.patch
@@ -0,0 +1,30 @@
+crt: add missing __MINGW_IMP_SYMBOL for _strtof_l and _wcstof_l
+
+These functions are static emulations present in every libmsvcr*.a,
+but the headers declare them dllimport (_CRTIMP), so callers reference
+__imp__strtof_l and __imp__wcstof_l, which nothing defines, and the
+link fails. Define fake import pointers alongside the definitions, as
+already done for other statically-emulated functions such as
+__acrt_iob_func and _initialize_onexit_table.
+
+The _strtof_l half was merged upstream after v14.0.0 as 373c7dd0
+("crt: Add missing __MINGW_IMP_SYMBOL for _strtof_l()"). The
+_wcstof_l half is the same fix for the wide variant, which remains
+broken upstream.
+
+--- a/mingw-w64-crt/stdio/_strtof_l.c
++++ b/mingw-w64-crt/stdio/_strtof_l.c
+@@ -26,3 +26,5 @@
+   }
+   return ret;
+ }
++
++float (*__MINGW_IMP_SYMBOL(_strtof_l))(const char *, char **, _locale_t) = _strtof_l;
+--- a/mingw-w64-crt/stdio/_wcstof_l.c
++++ b/mingw-w64-crt/stdio/_wcstof_l.c
+@@ -26,3 +26,5 @@
+   }
+   return ret;
+ }
++
++float (*__MINGW_IMP_SYMBOL(_wcstof_l))(const wchar_t *, wchar_t **, _locale_t) = _wcstof_l;