Fix static archives stripping (#5905)

* Do not strip static archives

Stripping static archives without more fine-grained options (e.g. `-g`)
leads to failures such as

    ld: libfoo.a: error adding symbols: archive has no index; run ranlib to add one

because GNU strip removes *every* symbol in a static archive by default.
Given that static archives are not final build artifacts (unlike
executables and shared libraries), stripping them gains little and only
causes more edge case failures.

* Gentoo's portage only strips debug information:
  86f211e3a5/bin/estrip (L322)
* Fedora also only strips debug information:
  e9c13c6565/scripts/brp-strip-static-archive (L18)
* Debian also only does some very light stripping:
  72ed1d3261/dh_strip (L374)

Fixes #4138

* Add test case for static archive stripping

mesonbuild/backend/backends.py

@@ -1089,7 +1089,20 @@ class Backend:
             install_mode = t.get_custom_install_mode()
             # Install the target output(s)
             if isinstance(t, build.BuildTarget):
-                should_strip = self.get_option_for_target('strip', t)
+                # In general, stripping static archives is tricky and full of pitfalls.
+                # Wholesale stripping of static archives with a command such as
+                #
+                #   strip libfoo.a
+                #
+                # is broken, as GNU's strip will remove *every* symbol in a static
+                # archive. One solution to this nonintuitive behaviour would be
+                # to only strip local/debug symbols. Unfortunately, strip arguments
+                # are not specified by POSIX and therefore not portable. GNU's `-g`
+                # option (i.e. remove debug symbols) is equivalent to Apple's `-S`.
+                #
+                # TODO: Create GNUStrip/AppleStrip/etc. hierarchy for more
+                #       fine-grained stripping of static archives.
+                should_strip = not isinstance(t, build.StaticLibrary) and self.get_option_for_target('strip', t)
                 # Install primary build output (library/executable/jar, etc)
                 # Done separately because of strip/aliases/rpath
                 if outdirs[0] is not False:

run_unittests.py

@@ -5330,6 +5330,33 @@ endian = 'little'
                       override_envvars={'PKG_CONFIG_PATH': ':'.join(pkg_dir)})
             self.build()
 
+    @skipIfNoPkgconfig
+    def test_static_archive_stripping(self):
+        '''
+        Check that Meson produces valid static archives with --strip enabled
+        '''
+        with tempfile.TemporaryDirectory() as tempdirname:
+            testdirbase = os.path.join(self.unit_test_dir, '68 static archive stripping')
+
+            # build lib
+            self.new_builddir()
+            testdirlib = os.path.join(testdirbase, 'lib')
+            testlibprefix = os.path.join(tempdirname, 'libprefix')
+            self.init(testdirlib, extra_args=['--prefix=' + testlibprefix,
+                                              '--libdir=lib',
+                                              '--default-library=static',
+                                              '--buildtype=debug',
+                                              '--strip'], default_args=False)
+            self.build()
+            self.install(use_destdir=False)
+
+            # build executable (uses lib, fails if static archive has been stripped incorrectly)
+            pkg_dir = os.path.join(testlibprefix, 'lib/pkgconfig')
+            self.new_builddir()
+            self.init(os.path.join(testdirbase, 'app'),
+                      override_envvars={'PKG_CONFIG_PATH': pkg_dir})
+            self.build()
+
     @skipIfNoPkgconfig
     def test_pkgconfig_formatting(self):
         testdir = os.path.join(self.unit_test_dir, '38 pkgconfig format')

test cases/unit/68 static archive stripping/app/appA.c

@@ -0,0 +1,4 @@
+#include <stdio.h>
+#include <libA.h>
+
+int main() { printf("The answer is: %d\n", libA_func()); }

test cases/unit/68 static archive stripping/app/appB.c

@@ -0,0 +1,4 @@
+#include <stdio.h>
+#include <libB.h>
+
+int main() { printf("The answer is: %d\n", libB_func()); }

test cases/unit/68 static archive stripping/app/meson.build

@@ -0,0 +1,7 @@
+project('app', ['c'])
+
+a = dependency('test-a')
+b = dependency('test-b')
+
+executable('appA', files('appA.c'), dependencies : a)
+executable('appB', files('appB.c'), dependencies : b)

test cases/unit/68 static archive stripping/lib/libA.c

@@ -0,0 +1,5 @@
+#include <libA.h>
+
+static int libA_func_impl(void) { return 0; }
+
+int libA_func(void) { return libA_func_impl(); }

test cases/unit/68 static archive stripping/lib/libA.h

@@ -0,0 +1 @@
+int libA_func(void);

test cases/unit/68 static archive stripping/lib/libB.c

@@ -0,0 +1,5 @@
+#include <libB.h>
+
+static int libB_func_impl(void) { return 0; }
+
+int libB_func(void) { return libB_func_impl(); }

test cases/unit/68 static archive stripping/lib/libB.h

@@ -0,0 +1 @@
+int libB_func(void);

test cases/unit/68 static archive stripping/lib/meson.build

@@ -0,0 +1,23 @@
+project('lib', ['c'])
+
+pkg = import('pkgconfig')
+
+a = library('test-a', files('libA.c'), install: true)
+install_headers(files('libA.h'), subdir: 'libA')
+pkg.generate(
+    a,
+    version: '0.0',
+    description: 'test library libA',
+    filebase: 'test-a',
+    name: 'test library libA',
+    subdirs: 'libA')
+
+b = static_library('test-b', files('libB.c'), install: true)
+install_headers(files('libB.h'), subdir: 'libB')
+pkg.generate(
+    b,
+    version: '0.0',
+    description: 'test library libB',
+    filebase: 'test-b',
+    name: 'test library libB',
+    subdirs: 'libB')