From b46aae093634271931395d65f422f4b2a23112d3 Mon Sep 17 00:00:00 2001
From: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
Date: Mon, 25 Jan 2016 01:42:23 +0100
Subject: [PATCH] build: use a link instead of changing current directory when
 compiling

If links don't work, fall back to using the full source path as was
previously done.

This should fix build failures with MSVC.

Reviewed-by: Hendrik Leppkes <h.leppkes@gmail.com>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
---
 .gitignore  |  1 +
 Makefile    |  2 +-
 common.mak  |  7 +++----
 configure   | 28 +++++++++++++++++++++-------
 library.mak |  2 +-
 5 files changed, 27 insertions(+), 13 deletions(-)

diff --git a/.gitignore b/.gitignore
index 93b0dca40a..9fc0ac269c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -64,6 +64,7 @@
 /libavcodec/*_tables.h
 /libavutil/avconfig.h
 /libavutil/ffversion.h
+/src
 /tests/audiogen
 /tests/base64
 /tests/checkasm/checkasm
diff --git a/Makefile b/Makefile
index f3bd5f682d..e484249065 100644
--- a/Makefile
+++ b/Makefile
@@ -181,7 +181,7 @@ clean::
 
 distclean::
 	$(RM) $(DISTCLEANSUFFIXES)
-	$(RM) config.* .config libavutil/avconfig.h .version avversion.h version.h libavutil/ffversion.h libavcodec/codec_names.h
+	$(RM) config.* .config libavutil/avconfig.h .version avversion.h version.h libavutil/ffversion.h libavcodec/codec_names.h src
 	$(RM) -rf doc/examples/pc-uninstalled
 
 config:
diff --git a/common.mak b/common.mak
index 3812149ef5..03b51c5968 100644
--- a/common.mak
+++ b/common.mak
@@ -32,7 +32,7 @@ endif
 ALLFFLIBS = avcodec avdevice avfilter avformat avresample avutil postproc swscale swresample
 
 # NASM requires -I path terminated with /
-IFLAGS     := -I$(DST_PATH)/ -I$(SRC_PATH)/
+IFLAGS     := -I. -I$(SRC_LINK)/
 CPPFLAGS   := $(IFLAGS) $(CPPFLAGS)
 CFLAGS     += $(ECFLAGS)
 CCFLAGS     = $(CPPFLAGS) $(CFLAGS)
@@ -43,12 +43,11 @@ CXXFLAGS   += $(CPPFLAGS) $(CFLAGS)
 YASMFLAGS  += $(IFLAGS:%=%/) -Pconfig.asm
 
 HOSTCCFLAGS = $(IFLAGS) $(HOSTCPPFLAGS) $(HOSTCFLAGS)
-LDFLAGS    := $(ALLFFLIBS:%=$(LD_PATH)$(DST_PATH)/lib%) $(LDFLAGS)
+LDFLAGS    := $(ALLFFLIBS:%=$(LD_PATH)lib%) $(LDFLAGS)
 
 define COMPILE
        $(call $(1)DEP,$(1))
-       $(Q)cd $(SRC_PATH); if [ -n "$(findstring $(SRC_PATH),$<)" ]; then dest=$(subst $(SRC_PATH)/,,$<); else dest=$(DST_PATH)/$<; fi; \
-       $(subst @,,$($(1))) $($(1)FLAGS) $($(1)_DEPFLAGS:$(@:.o=.d)=$(DST_PATH)/$(@:.o=.d)) $($(1)_C) $($(1)_O:$@=$(DST_PATH)/$@) $$dest
+       $($(1)) $($(1)FLAGS) $($(1)_DEPFLAGS) $($(1)_C) $($(1)_O) $(patsubst $(SRC_PATH)/%,$(SRC_LINK)/%,$<)
 endef
 
 COMPILE_C = $(call COMPILE,CC)
diff --git a/configure b/configure
index 0685133975..57b526fce9 100755
--- a/configure
+++ b/configure
@@ -4696,6 +4696,26 @@ case $target_os in
         ;;
 esac
 
+# test if creating links works
+link_dest=$(mktemp -u $TMPDIR/dest_XXXXXXXX)
+link_name=$(mktemp -u $TMPDIR/name_XXXXXXXX)
+mkdir "$link_dest"
+$ln_s "$link_dest" "$link_name"
+touch "$link_dest/test_file"
+if [ -e "$link_name/test_file" ]; then
+    # create link to source path
+    [ -e src ] && rm src
+    $ln_s "$source_path" src
+    source_link=src
+else
+    # creating directory links doesn't work
+    # fall back to using the full source path
+    source_link="$source_path"
+fi
+# cleanup
+rm -r "$link_dest"
+rm -r "$link_name"
+
 # determine libc flavour
 
 probe_libc(){
@@ -6229,12 +6249,6 @@ enabled stripping || strip="echo skipping strip"
 
 config_files="$TMPH config.mak doc/config.texi"
 
-if enabled msvc; then
-    dst_path=$(pwd -W)
-else
-    dst_path=$(pwd)
-fi
-
 cat > config.mak <<EOF
 # Automatically generated by configure - do not modify!
 ifndef FFMPEG_CONFIG_MAK
@@ -6250,10 +6264,10 @@ DOCDIR=\$(DESTDIR)$docdir
 MANDIR=\$(DESTDIR)$mandir
 PKGCONFIGDIR=\$(DESTDIR)$pkgconfigdir
 SRC_PATH=$source_path
+SRC_LINK=$source_link
 ifndef MAIN_MAKEFILE
 SRC_PATH:=\$(SRC_PATH:.%=..%)
 endif
-DST_PATH=$dst_path
 CC_IDENT=$cc_ident
 ARCH=$arch
 INTRINSICS=$intrinsics
diff --git a/library.mak b/library.mak
index 0b23a28f5b..3e1082c572 100644
--- a/library.mak
+++ b/library.mak
@@ -28,7 +28,7 @@ $(SUBDIR)x86/%$(DEFAULT_YASMD).asm: $(SUBDIR)x86/%.asm
 
 $(SUBDIR)x86/%.o: $(SUBDIR)x86/%$(YASMD).asm
 	$(DEPYASM) $(YASMFLAGS) -I $(<D)/ -M -o $@ $< > $(@:.o=.d)
-	$(Q)cd $(SRC_PATH); $(subst @,,$(YASM)) $(YASMFLAGS) -I $(<D)/ -o $(DST_PATH)/$@ $(subst $(SRC_PATH)/,,$<)
+	$(YASM) $(YASMFLAGS) -I $(<D)/ -o $@ $(patsubst $(SRC_PATH)/%,$(SRC_LINK)/%,$<)
 	-$(if $(ASMSTRIPFLAGS), $(STRIP) $(ASMSTRIPFLAGS) $@)
 
 LIBOBJS := $(OBJS) $(SUBDIR)%.h.o $(TESTOBJS)