--- /dev/null
+From ab9a34c92eec815ef214470c927ddbe2e950e7e5 Mon Sep 17 00:00:00 2001
+From: Joshua Watt <JPEWhacker@gmail.com>
+Date: Wed, 26 May 2021 09:15:40 -0500
+Subject: [PATCH] MinGW Build Fixes
+
+Fixes building on MinGW by
+ 1) Exporting the OS variable so that it is visible to sub-make
+ invocations
+ 2) Fixing the extension handling so that make correctly identifies when
+ targets need to be rebuilt. Without the correct handling, make would
+ rebuild the executable targets when running `make install` because
+ it couldn't find them with the correct extension.
+
+Upstream-Status: Submitted [https://github.com/facebook/zstd/pull/2685]
+Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>
+---
+ Makefile | 1 +
+ programs/Makefile | 74 +++++++++++++++++++++++------------------------
+ 2 files changed, 38 insertions(+), 37 deletions(-)
+
+diff --git a/Makefile b/Makefile
+index c1908f0a..f9ce9504 100644
+--- a/Makefile
++++ b/Makefile
+@@ -29,6 +29,7 @@ VOID = /dev/null
+ # fail on other tested distros (ubuntu, debian) even
+ # without manually specifying the TARGET_SYSTEM.
+ TARGET_SYSTEM ?= $(OS)
++export OS
+
+ ifneq (,$(filter Windows%,$(TARGET_SYSTEM)))
+ EXT =.exe
+diff --git a/programs/Makefile b/programs/Makefile
+index 599fb02f..79b45c83 100644
+--- a/programs/Makefile
++++ b/programs/Makefile
+@@ -209,37 +209,37 @@ SET_CACHE_DIRECTORY = \
+
+
+ .PHONY: all
+-all: zstd
++all: zstd$(EXT)
+
+ .PHONY: allVariants
+-allVariants: zstd zstd-compress zstd-decompress zstd-small zstd-nolegacy zstd-dictBuilder
++allVariants: zstd$(EXT) zstd-compress$(EXT) zstd-decompress$(EXT) zstd-small$(EXT) zstd-nolegacy$(EXT) zstd-dictBuilder$(EXT)
+
+ .PHONY: zstd # must always be run
+-zstd : CPPFLAGS += $(THREAD_CPP) $(ZLIBCPP) $(LZMACPP) $(LZ4CPP)
+-zstd : LDFLAGS += $(THREAD_LD) $(DEBUGFLAGS_LD)
+-zstd : LDLIBS += $(ZLIBLD) $(LZMALD) $(LZ4LD)
+-zstd : CPPFLAGS += -DZSTD_LEGACY_SUPPORT=$(ZSTD_LEGACY_SUPPORT)
++zstd$(EXT) : CPPFLAGS += $(THREAD_CPP) $(ZLIBCPP) $(LZMACPP) $(LZ4CPP)
++zstd$(EXT) : LDFLAGS += $(THREAD_LD) $(DEBUGFLAGS_LD)
++zstd$(EXT) : LDLIBS += $(ZLIBLD) $(LZMALD) $(LZ4LD)
++zstd$(EXT) : CPPFLAGS += -DZSTD_LEGACY_SUPPORT=$(ZSTD_LEGACY_SUPPORT)
+ ifneq (,$(filter Windows%,$(OS)))
+-zstd : $(RES_FILE)
++zstd$(EXT) : $(RES_FILE)
+ endif
+
+ ifndef BUILD_DIR
+ # generate BUILD_DIR from flags
+
+-zstd:
++zstd$(EXT):
+ $(SET_CACHE_DIRECTORY)
+
+ else
+ # BUILD_DIR is defined
+
+ ZSTD_OBJ := $(addprefix $(BUILD_DIR)/, $(ZSTD_ALL_OBJ))
+-$(BUILD_DIR)/zstd : $(ZSTD_OBJ)
++$(BUILD_DIR)/zstd$(EXT) : $(ZSTD_OBJ)
+ @echo "$(THREAD_MSG)"
+ @echo "$(ZLIB_MSG)"
+ @echo "$(LZMA_MSG)"
+ @echo "$(LZ4_MSG)"
+ @echo LINK $@
+- $(CC) $(FLAGS) $^ $(LDLIBS) -o $@$(EXT)
++ $(CC) $(FLAGS) $^ $(LDLIBS) -o $@
+
+ ifeq ($(HAVE_HASH),1)
+ SRCBIN_HASH = $(shell cat $(BUILD_DIR)/zstd 2> $(VOID) | $(HASH) | cut -f 1 -d " ")
+@@ -249,7 +249,7 @@ else
+ BIN_ISDIFFERENT = 1
+ endif
+
+-zstd : $(BUILD_DIR)/zstd
++zstd$(EXT) : $(BUILD_DIR)/zstd$(EXT)
+ if [ $(BIN_ISDIFFERENT) -eq 1 ]; then \
+ cp -f $< $@; \
+ echo zstd build completed; \
+@@ -263,46 +263,46 @@ endif # BUILD_DIR
+ .PHONY: zstd-release
+ zstd-release: DEBUGFLAGS := -DBACKTRACE_ENABLE=0
+ zstd-release: DEBUGFLAGS_LD :=
+-zstd-release: zstd
++zstd-release: zstd$(EXT)
+
+-zstd32 : CPPFLAGS += $(THREAD_CPP)
+-zstd32 : LDFLAGS += $(THREAD_LD)
+-zstd32 : CPPFLAGS += -DZSTD_LEGACY_SUPPORT=$(ZSTD_LEGACY_SUPPORT)
++zstd32$(EXT) : CPPFLAGS += $(THREAD_CPP)
++zstd32$(EXT) : LDFLAGS += $(THREAD_LD)
++zstd32$(EXT) : CPPFLAGS += -DZSTD_LEGACY_SUPPORT=$(ZSTD_LEGACY_SUPPORT)
+ ifneq (,$(filter Windows%,$(OS)))
+-zstd32 : $(RES32_FILE)
++zstd32$(EXT) : $(RES32_FILE)
+ endif
+-zstd32 : $(ZSTDLIB_FULL_SRC) $(ZSTD_CLI_SRC)
+- $(CC) -m32 $(FLAGS) $^ -o $@$(EXT)
++zstd32$(EXT) : $(ZSTDLIB_FULL_SRC) $(ZSTD_CLI_SRC)
++ $(CC) -m32 $(FLAGS) $^ -o $@
+
+ ## zstd-nolegacy: same scope as zstd, with just support of legacy formats removed
+-zstd-nolegacy : LDFLAGS += $(THREAD_LD) $(ZLIBLD) $(LZMALD) $(LZ4LD) $(DEBUGFLAGS_LD)
+-zstd-nolegacy : $(ZSTDLIB_CORE_SRC) $(ZDICT_SRC) $(ZSTD_CLI_OBJ)
+- $(CC) $(FLAGS) $^ -o $@$(EXT) $(LDFLAGS)
++zstd-nolegacy$(EXT) : LDFLAGS += $(THREAD_LD) $(ZLIBLD) $(LZMALD) $(LZ4LD) $(DEBUGFLAGS_LD)
++zstd-nolegacy$(EXT) : $(ZSTDLIB_CORE_SRC) $(ZDICT_SRC) $(ZSTD_CLI_OBJ)
++ $(CC) $(FLAGS) $^ -o $@ $(LDFLAGS)
+
+ .PHONY: zstd-nomt
+ zstd-nomt : THREAD_CPP :=
+ zstd-nomt : THREAD_LD :=
+ zstd-nomt : THREAD_MSG := - multi-threading disabled
+-zstd-nomt : zstd
++zstd-nomt : zstd$(EXT)
+
+ .PHONY: zstd-nogz
+ zstd-nogz : ZLIBCPP :=
+ zstd-nogz : ZLIBLD :=
+ zstd-nogz : ZLIB_MSG := - gzip support is disabled
+-zstd-nogz : zstd
++zstd-nogz : zstd$(EXT)
+
+ .PHONY: zstd-noxz
+ zstd-noxz : LZMACPP :=
+ zstd-noxz : LZMALD :=
+ zstd-noxz : LZMA_MSG := - xz/lzma support is disabled
+-zstd-noxz : zstd
++zstd-noxz : zstd$(EXT)
+
+ ## zstd-dll: zstd executable linked to dynamic library libzstd (must have same version)
+ .PHONY: zstd-dll
+ zstd-dll : LDFLAGS+= -L$(ZSTDDIR)
+ zstd-dll : LDLIBS += -lzstd
+ zstd-dll : ZSTDLIB_LOCAL_SRC = xxhash.c
+-zstd-dll : zstd
++zstd-dll : zstd$(EXT)
+
+
+ ## zstd-pgo: zstd executable optimized with PGO.
+@@ -321,23 +321,23 @@ zstd-pgo :
+ $(MAKE) zstd MOREFLAGS=-fprofile-use
+
+ ## zstd-small: minimal target, supporting only zstd compression and decompression. no bench. no legacy. no other format.
+-zstd-small: CFLAGS = -Os -s
+-zstd-frugal zstd-small: $(ZSTDLIB_CORE_SRC) zstdcli.c util.c timefn.c fileio.c
+- $(CC) $(FLAGS) -DZSTD_NOBENCH -DZSTD_NODICT -DZSTD_NOTRACE $^ -o $@$(EXT)
++zstd-small$(EXT): CFLAGS = -Os -s
++zstd-frugal$(EXT) zstd-small$(EXT): $(ZSTDLIB_CORE_SRC) zstdcli.c util.c timefn.c fileio.c
++ $(CC) $(FLAGS) -DZSTD_NOBENCH -DZSTD_NODICT -DZSTD_NOTRACE $^ -o $@
+
+-zstd-decompress: $(ZSTDLIB_COMMON_C) $(ZSTDLIB_DECOMPRESS_C) zstdcli.c util.c timefn.c fileio.c
+- $(CC) $(FLAGS) -DZSTD_NOBENCH -DZSTD_NODICT -DZSTD_NOCOMPRESS -DZSTD_NOTRACE $^ -o $@$(EXT)
++zstd-decompress$(EXT): $(ZSTDLIB_COMMON_C) $(ZSTDLIB_DECOMPRESS_C) zstdcli.c util.c timefn.c fileio.c
++ $(CC) $(FLAGS) -DZSTD_NOBENCH -DZSTD_NODICT -DZSTD_NOCOMPRESS -DZSTD_NOTRACE $^ -o $@
+
+-zstd-compress: $(ZSTDLIB_COMMON_C) $(ZSTDLIB_COMPRESS_C) zstdcli.c util.c timefn.c fileio.c
+- $(CC) $(FLAGS) -DZSTD_NOBENCH -DZSTD_NODICT -DZSTD_NODECOMPRESS -DZSTD_NOTRACE $^ -o $@$(EXT)
++zstd-compress$(EXT): $(ZSTDLIB_COMMON_C) $(ZSTDLIB_COMPRESS_C) zstdcli.c util.c timefn.c fileio.c
++ $(CC) $(FLAGS) -DZSTD_NOBENCH -DZSTD_NODICT -DZSTD_NODECOMPRESS -DZSTD_NOTRACE $^ -o $@
+
+ ## zstd-dictBuilder: executable supporting dictionary creation and compression (only)
+-zstd-dictBuilder: CPPFLAGS += -DZSTD_NOBENCH -DZSTD_NODECOMPRESS -DZSTD_NOTRACE
+-zstd-dictBuilder: $(ZSTDLIB_COMMON_C) $(ZSTDLIB_COMPRESS_C) $(ZDICT_SRC) zstdcli.c util.c timefn.c fileio.c dibio.c
+- $(CC) $(FLAGS) $^ -o $@$(EXT)
++zstd-dictBuilder$(EXT): CPPFLAGS += -DZSTD_NOBENCH -DZSTD_NODECOMPRESS -DZSTD_NOTRACE
++zstd-dictBuilder$(EXT): $(ZSTDLIB_COMMON_C) $(ZSTDLIB_COMPRESS_C) $(ZDICT_SRC) zstdcli.c util.c timefn.c fileio.c dibio.c
++ $(CC) $(FLAGS) $^ -o $@
+
+-zstdmt: zstd
+- ln -sf zstd zstdmt
++zstdmt$(EXT): zstd$(EXT)
++ ln -sf zstd$(EXT) zstdmt$(EXT)
+
+ .PHONY: generate_res
+ generate_res: $(RES64_FILE) $(RES32_FILE)
+--
+2.31.1
+
