interactive builds: /ro/include/iconv.h is picked up from libiconv instead of glibc

[stapelberg]

Currently using the following workaround to build i3 from git:

CPATH=/ro/glibc-amd64-2.27-3/out/include:$CPATH make -j8

Need to look into why configure does not detect -liconv, but linking fails without it (unless using the workaround).

[stapelberg]

The glibc include dir is missing from the wrapper script contents because of

distri/cmd/distri/build.go

Lines 734 to 745 in 54756a6

	// Exclude glibc from CPATH: it needs to come last (as /usr/include),
	// and gcc doesn’t recognize that the non-system directory glibc-2.27
	// duplicates the system directory /usr/include because we only symlink
	// the contents, not the whole directory.
	if dep != "glibc-amd64-2.27-4" && dep != "glibc-i686-amd64-2.27-4" &&
	dep != "glibc-amd64-2.27-3" && dep != "glibc-i686-amd64-2.27-3" &&
	dep != "glibc-amd64-2.27-2" && dep != "glibc-i686-amd64-2.27-2" &&
	dep != "glibc-amd64-2.27-1" && dep != "glibc-i686-amd64-2.27-1" &&
	dep != "glibc-amd64-2.27" && dep != "glibc-i686-amd64-2.27" {
	includeDirs = append(includeDirs, "/ro/"+dep+"/out/include")
	includeDirs = append(includeDirs, "/ro/"+dep+"/out/include/x86_64-linux-gnu")
	}

Maybe we need to look into teaching gcc that /ro/glibc…/out/include is a system directory?

[stapelberg]

Need to look into why configure does not detect -liconv, but linking fails without it (unless using the workaround).

Turns out that autoconf’s AC_SEARCH_LIBS does not put an #include directive into its conftest.c file, so it gets the builtin iconv instead of the one requiring libiconv.

Fixing this in i3’s configure.ac in i3/i3#3942, but of course other upstream software might still use AC_SEARCH_LIBS for detecting iconv.