fix: address PR review comments

- rts/configure.ac: Use portable ${MKDIR_P} instead of mkdir -p
  (AC_PROG_MKDIR_P macro for better portability across systems)

- Makefile: Replace for loops with find -exec for creating symlinks
  (cleaner and avoids issues with special characters in filenames)

- Makefile: Add explanatory comments for symlink creation
  (explains why RTS sublibraries need top-level symlinks)

Author: angerman

Makefile

@@ -956,12 +956,14 @@ _build/bindist: stage2 driver/ghc-usage.txt driver/ghci-usage.txt
 	$@/bin/ghc-pkg$(EXE_EXT) recache
 	# Copy headers
 	@$(call copy_all_stage2_h,$@/bin/ghc-pkg$(EXE_EXT))
-	# Add basename symlinks for nested shared libs (.dylib, .so) in lib/$(HOST_PLATFORM)
+	# Add basename symlinks for nested shared libs (.dylib, .so) in
+	# lib/$(HOST_PLATFORM). Shared libraries may be installed in subdirectories
+	# (e.g., lib/x86_64-linux/rts-1.0.3/). We create symlinks at the top level
+	# so all shared libraries are in one folder.
 	@if [ -d "$@/lib/$(HOST_PLATFORM)" ]; then \
-	  cd "$@/lib/$(HOST_PLATFORM)" ; \
-	  for lib in $$(find . -mindepth 2 \( -name "*.dylib" -o -name "*.so" \) -type f) ; do \
-	    ln -sf "$$lib" "$$(basename "$$lib")" ; \
-	  done ; \
+	  cd "$@/lib/$(HOST_PLATFORM)" && \
+	  find . -mindepth 2 \( -name "*.dylib" -o -name "*.so" \) -type f \
+	    -exec sh -c 'ln -sf "$$1" "$$(basename "$$1")"' _ {} \; ; \
 	fi
 	# Create -dyn iserv executable (symlink so ghc can find ghc-iserv-dyn)
 	@ln -sf ghc-iserv$(EXE_EXT) "$@/bin/ghc-iserv-dyn$(EXE_EXT)"
@@ -989,12 +991,12 @@ _build/bindist/lib/targets/%: _build/bindist driver/ghc-usage.txt driver/ghci-us
 	# Copy libraries and settings
 	@if [ -e $(CURDIR)/_build/bindist/lib/targets/$(@F)/lib/$(@F) ] ; then find $(CURDIR)/_build/bindist/lib/targets/$(@F)/lib/$(@F)/ -mindepth 1 -type f -name "*.so" -execdir mv '{}' $(CURDIR)/_build/bindist/lib/targets/$(@F)/lib/$(@F)/'{}' \; ; fi
 	$(call copycrosslib,$(@F))
-	# Add basename symlinks for nested shared libs (.dylib, .so) in lib/$(@F)
+	# Add basename symlinks for nested shared libs (.dylib, .so) in lib/$(@F).
+	# See comment in _build/bindist target for explanation.
 	@if [ -d $(CURDIR)/_build/bindist/lib/targets/$(@F)/lib/$(@F) ] ; then \
-	  cd $(CURDIR)/_build/bindist/lib/targets/$(@F)/lib/$(@F) ; \
-	  for lib in $$(find . -mindepth 2 \( -name "*.dylib" -o -name "*.so" \) -type f) ; do \
-	    ln -sf "$$lib" "$$(basename "$$lib")" ; \
-	  done ; \
+	  cd $(CURDIR)/_build/bindist/lib/targets/$(@F)/lib/$(@F) && \
+	  find . -mindepth 2 \( -name "*.dylib" -o -name "*.so" \) -type f \
+	    -exec sh -c 'ln -sf "$$1" "$$(basename "$$1")"' _ {} \; ; \
 	fi
 	# --help
 	@cp -rfp driver/ghc-usage.txt _build/bindist/lib/targets/$(@F)/lib/

rts/configure.ac

@@ -57,6 +57,9 @@ dnl detect compiler (prefer gcc over clang) and set $CC (unless CC already set),
 dnl later CC is copied to CC_STAGE{1,2,3}
 AC_PROG_CC([cc gcc clang])
 
+dnl Portable mkdir -p (sets MKDIR_P)
+AC_PROG_MKDIR_P
+
 dnl make extensions visible to allow feature-tests to detect them lateron
 AC_USE_SYSTEM_EXTENSIONS
 
@@ -444,7 +447,7 @@ dnl Generate ghcplatform.h
 dnl ######################################################################
 
 [
-mkdir -p include
+${MKDIR_P} include
 
 touch include/ghcplatform.h
 > include/ghcplatform.h
@@ -537,47 +540,47 @@ else
 fi
 
 AC_MSG_CHECKING([for include/rts/AutoApply.cmm.h])
-if mkdir -p include/rts && $GENAPPLY include/DerivedConstants.h > include/rts/AutoApply.cmm.h; then
+if ${MKDIR_P} include/rts && $GENAPPLY include/DerivedConstants.h > include/rts/AutoApply.cmm.h; then
   AC_MSG_RESULT([created])
 else
   AC_MSG_RESULT([failed to create])
   AC_MSG_ERROR([Failed to run $GENAPPLY include/DerivedConstants.h > include/rts/AutoApply.cmm.h])
 fi
 
 AC_MSG_CHECKING([for include/rts/AutoApply_V16.cmm.h])
-if mkdir -p include/rts && $GENAPPLY include/DerivedConstants.h -V16 > include/rts/AutoApply_V16.cmm.h; then
+if ${MKDIR_P} include/rts && $GENAPPLY include/DerivedConstants.h -V16 > include/rts/AutoApply_V16.cmm.h; then
   AC_MSG_RESULT([created])
 else
   AC_MSG_RESULT([failed to create])
   AC_MSG_ERROR([Failed to run $GENAPPLY include/DerivedConstants.h -V16 > include/rts/AutoApply_V16.cmm.h])
 fi
 
 AC_MSG_CHECKING([for include/rts/AutoApply_V32.cmm.h])
-if mkdir -p include/rts && $GENAPPLY include/DerivedConstants.h -V32 > include/rts/AutoApply_V32.cmm.h; then
+if ${MKDIR_P} include/rts && $GENAPPLY include/DerivedConstants.h -V32 > include/rts/AutoApply_V32.cmm.h; then
   AC_MSG_RESULT([created])
 else
   AC_MSG_RESULT([failed to create])
   AC_MSG_ERROR([Failed to run $GENAPPLY include/DerivedConstants.h -V32 > include/rts/AutoApply_V32.cmm.h])
 fi
 
 AC_MSG_CHECKING([for include/rts/AutoApply_V64.cmm.h])
-if mkdir -p include/rts && $GENAPPLY include/DerivedConstants.h -V64 > include/rts/AutoApply_V64.cmm.h; then
+if ${MKDIR_P} include/rts && $GENAPPLY include/DerivedConstants.h -V64 > include/rts/AutoApply_V64.cmm.h; then
   AC_MSG_RESULT([created])
 else
   AC_MSG_RESULT([failed to create])
   AC_MSG_ERROR([Failed to run $GENAPPLY include/DerivedConstants.h -V64 > include/rts/AutoApply_V64.cmm.h])
 fi
 
 AC_MSG_CHECKING([for include/rts/EventLogConstants.h])
-if mkdir -p include/rts && $PYTHON $srcdir/gen_event_types.py --event-types-defines include/rts/EventLogConstants.h; then
+if ${MKDIR_P} include/rts && $PYTHON $srcdir/gen_event_types.py --event-types-defines include/rts/EventLogConstants.h; then
   AC_MSG_RESULT([created])
 else
   AC_MSG_RESULT([failed to create])
   AC_MSG_ERROR([Failed to run $PYTHON gen_event_types.py])
 fi
 
 AC_MSG_CHECKING([for include/rts/EventTypes.h])
-if mkdir -p include/rts && $PYTHON $srcdir/gen_event_types.py --event-types-array include/rts/EventTypes.h; then
+if ${MKDIR_P} include/rts && $PYTHON $srcdir/gen_event_types.py --event-types-array include/rts/EventTypes.h; then
   AC_MSG_RESULT([created])
 else
   AC_MSG_RESULT([failed to create])