Subject: Re: [BUG] `make install' partly ignores `NO_INSTALL_HARDLINKS'

From: Đoàn Trần Công Danh <[email-masked]>
Date: Sat, 15 Aug 2020 08:15:56 +0700

On 2020-08-14 10:26:24-0700, Junio C Hamano <[email-masked]> wrote:
> > Since both git-citool and git-gui will be installed into same
> > directory "$(libexecdir)", I think it would make more sense to use:
> >
> > 	LN = ln -s
> >
> > here instead?
> 
> In the top-level Makefile, INSTALL_SYMLINKS make macro does exist,
> but it is not exported to submakes.  If it were, something like
> 
>     ifdef INSTALL_SYMLINKS
> 	LN = ln -s
>     else
>     ifdef NO_INSTALL_HARDLINKS
> 	LN = cp
>     else
> 	LN = ln
>     endif
>     endif
> 
> might become possible, but you'd need to audit what is fed to $(LN)
> at the locations the macro is used and make necessary adjustment
> accordingly.  "cp A ../B" or "ln A ../B" will make a usable copy of
> file A appear inside ../B directory, but "ln -s A ../B" will not,
> and I didn't see if all uses of $(LN) was to give synonyms to what
> is already installed, or some of them were truly installing from the
> build location when I gave the "something along this line" example.

Yes, the top-level Makefile seems to have a special branch for
BUILT_INS, in which, we will create symlink for those builtin in
libexecdr if NO_INSTALL_HARDLINKS is defined.

I was aiming for something like this to make git-gui a bit more
consistent with top-level Git, with or without INSTALL_SYMLINKS
exported:

----------8<--------
diff --git a/git-gui/Makefile b/git-gui/Makefile
index f10caedaa7..1a7d4b5075 100644
--- a/git-gui/Makefile
+++ b/git-gui/Makefile
@@ -48,6 +48,13 @@ endif
 RM_RF     ?= rm -rf
 RMDIR     ?= rmdir
 
+ifneq (,$(NO_INSTALL_HARDLINKS)$(INSTALL_SYMLINKS))
+	SAMEDIR_LN = ln -s
+else
+	SAMEDIR_LN = ln
+endif
+
+
 INSTALL_D0 = $(INSTALL) -d -m 755 # space is required here
 INSTALL_D1 =
 INSTALL_R0 = $(INSTALL) -m 644 # space is required here
@@ -57,7 +64,7 @@ INSTALL_X1 =
 INSTALL_A0 = find # space is required here
 INSTALL_A1 = | cpio -pud
 INSTALL_L0 = rm -f # space is required here
-INSTALL_L1 = && ln # space is required here
+INSTALL_L1 = && $(SAMEDIR_LN) # space is required here
 INSTALL_L2 =
 INSTALL_L3 =
 
@@ -87,7 +94,7 @@ ifndef V
 	INSTALL_L0 = dst=
 	INSTALL_L1 = && src=
 	INSTALL_L2 = && dst=
-	INSTALL_L3 = && echo '   ' 'LINK       ' `basename "$$dst"` '->' `basename "$$src"` && rm -f "$$dst" && ln "$$src" "$$dst"
+	INSTALL_L3 = && echo '   ' 'LINK       ' `basename "$$dst"` '->' `basename "$$src"` && rm -f "$$dst" && $(SAMEDIR_LN) "$$src" "$$dst"
 
 	CLEAN_DST = echo ' ' UNINSTALL
 	REMOVE_D0 = dir=
@@ -127,6 +134,12 @@ TCL_PATH_SQ = $(subst ','\'',$(TCL_PATH))
 TCLTK_PATH_SQ = $(subst ','\'',$(TCLTK_PATH))
 TCLTK_PATH_SED = $(subst ','\'',$(subst \,\\,$(TCLTK_PATH)))
 
+ifneq (,$(NO_INSTALL_HARDLINKS)$(INSTALL_SYMLINKS))
+	gitexecdir_SQ_for_LN =
+else
+	gitexecdir_SQ_for_LN = $(DESTDIR_SQ)$(gitexecdir_SQ)/
+endif
+
 gg_libdir ?= $(sharedir)/git-gui/lib
 libdir_SQ  = $(subst ','\'',$(gg_libdir))
 libdir_SED = $(subst ','\'',$(subst \,\\,$(gg_libdir_sed_in)))
@@ -293,7 +306,7 @@ install: all
 	$(QUIET)$(INSTALL_D0)'$(DESTDIR_SQ)$(gitexecdir_SQ)' $(INSTALL_D1)
 	$(QUIET)$(INSTALL_X0)git-gui $(INSTALL_X1) '$(DESTDIR_SQ)$(gitexecdir_SQ)'
 	$(QUIET)$(INSTALL_X0)git-gui--askpass $(INSTALL_X1) '$(DESTDIR_SQ)$(gitexecdir_SQ)'
-	$(QUIET)$(foreach p,$(GITGUI_BUILT_INS), $(INSTALL_L0)'$(DESTDIR_SQ)$(gitexecdir_SQ)/$p' $(INSTALL_L1)'$(DESTDIR_SQ)$(gitexecdir_SQ)/git-gui' $(INSTALL_L2)'$(DESTDIR_SQ)$(gitexecdir_SQ)/$p' $(INSTALL_L3) &&) true
+	$(QUIET)$(foreach p,$(GITGUI_BUILT_INS), $(INSTALL_L0)'$(DESTDIR_SQ)$(gitexecdir_SQ)/$p' $(INSTALL_L1)'$(gitexecdir_SQ_for_LN)git-gui' $(INSTALL_L2)'$(DESTDIR_SQ)$(gitexecdir_SQ)/$p' $(INSTALL_L3) &&) true
 ifdef GITGUI_WINDOWS_WRAPPER
 	$(QUIET)$(INSTALL_R0)git-gui.tcl $(INSTALL_R1) '$(DESTDIR_SQ)$(gitexecdir_SQ)'
 endif
-------->8-----------

Given that, we also tried to make symlinks when NO_INSTALL_SYMLINKS is
given, I think it's fine to assume that symlink should available on
those platform.

-- 
Danh