Make flags library header-only

The Abseil flags library needs to emit code only when being compiled
with MSVC, which Debian doesn’t use. Skip absl/flags/flag.cc, and tell
CMake to treat the flags library as header-only.

5 files changed, 22 insertions, 2 deletions

diff --git a/debian/changelog b/debian/changelog
index 0347674f..23869523 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,6 +1,8 @@
 abseil (0~20210324.2-1) UNRELEASED; urgency=medium
 
   * New upstream release.
+  * Stop installing libabsl_flags.so and libabsl_flags.a, since they are
+    empty on every platform that Debian supports.
   * Correct debian/watch search URLs to avoid picking up rc versions.
   * Mangle upstream version in debian/watch to match manual mangling in
     debian/changelog.
diff --git a/debian/libabsl20210324.lintian-overrides b/debian/libabsl20210324.lintian-overrides
index eda83e40..117966f8 100644
--- a/debian/libabsl20210324.lintian-overrides
+++ b/debian/libabsl20210324.lintian-overrides
@@ -30,7 +30,6 @@ libabsl20210324: library-not-linked-against-libc usr/lib/*/libabsl_throw_delegat
 libabsl20210324: no-symbols-control-file usr/lib/*/libabsl_*
 libabsl20210324: package-name-doesnt-match-sonames libabsl-*
 libabsl20210324: shared-library-lacks-prerequisites usr/lib/*/libabsl_city.so*
-libabsl20210324: shared-library-lacks-prerequisites usr/lib/*/libabsl_flags.so*
 libabsl20210324: shared-library-lacks-prerequisites usr/lib/*/libabsl_leak_check.so*
 libabsl20210324: shared-library-lacks-prerequisites usr/lib/*/libabsl_leak_check_disable.so*
 libabsl20210324: shared-library-lacks-prerequisites usr/lib/*/libabsl_random_internal_platform.so*
diff --git a/debian/libabsl20210324.shlibs b/debian/libabsl20210324.shlibs
index 73ea7090..f1ecca62 100644
--- a/debian/libabsl20210324.shlibs
+++ b/debian/libabsl20210324.shlibs
@@ -24,7 +24,6 @@ libabsl_demangle_internal 20210324 libabsl20210324 (>= 0~20210324.2-1)
 libabsl_examine_stack 20210324 libabsl20210324 (>= 0~20210324.2-1)
 libabsl_exponential_biased 20210324 libabsl20210324 (>= 0~20210324.2-1)
 libabsl_failure_signal_handler 20210324 libabsl20210324 (>= 0~20210324.2-1)
-libabsl_flags 20210324 libabsl20210324 (>= 0~20210324.2-1)
 libabsl_flags_commandlineflag 20210324 libabsl20210324 (>= 0~20210324.2-1)
 libabsl_flags_commandlineflag_internal 20210324 libabsl20210324 (>= 0~20210324.2-1)
 libabsl_flags_config 20210324 libabsl20210324 (>= 0~20210324.2-1)
diff --git a/debian/patches/empty-flags-library.diff b/debian/patches/empty-flags-library.diff
new file mode 100644
index 00000000..fe1d3962
--- /dev/null
+++ b/debian/patches/empty-flags-library.diff
@@ -0,0 +1,19 @@
+From: Benjamin Barenblat <bbaren@google.com>
+Subject: Eliminate libabsl_flags.so and libabsl_flags.a
+Forwarded: not-needed
+
+The libabsl_flags library only contains code when compiling with MSVC, which
+Debian doesn't use. Skip compiling absl/flags/flag.cc, and make the Abseil flags
+library header-only.
+
+--- a/absl/flags/CMakeLists.txt
++++ b/absl/flags/CMakeLists.txt
+@@ -197,8 +197,6 @@
+ absl_cc_library(
+   NAME
+     flags
+-  SRCS
+-    "flag.cc"
+   HDRS
+     "declare.h"
+     "flag.h"
diff --git a/debian/patches/series b/debian/patches/series
index 9cca595d..a954bf95 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -1,6 +1,7 @@
 configure.diff
 std-hash.diff
 latomic.diff
+empty-flags-library.diff
 cordrepring-typo.diff
 thumb-function-bounds.diff
 float-rounding.diff