Add cross-platform PIC support for static libraries

With C/C++, on Windows you don't need to pass any arguments for a static
library to be PIC. On UNIX platforms you need to pass -fPIC.

Other languages such as D have compiler-specific PIC arguments required
for PIC support in static libraries on UNIX platforms.

This kwarg allows people to specify which static libraries should be
built with PIC support. This is usually used for static libraries that
will be linked into shared libraries.

mesonbuild/backend/backends.py

@@ -341,6 +341,8 @@ class Backend():
             commands += compiler.get_werror_args()
         if isinstance(target, build.SharedLibrary):
             commands += compiler.get_pic_args()
+        if isinstance(target, build.StaticLibrary) and target.pic:
+            commands += compiler.get_pic_args()
         for dep in target.get_external_deps():
             # Cflags required by external deps might have UNIX-specific flags,
             # so filter them out if needed

mesonbuild/build.py

@@ -44,12 +44,19 @@ known_basic_kwargs = {'install' : True,
                       'native' : True,
                      }
 
-known_shlib_kwargs = known_basic_kwargs.copy()
-known_shlib_kwargs.update({'version' : True,
-                           'soversion' : True,
-                           'name_prefix' : True,
-                           'name_suffix' : True,
-                           'vs_module_defs' : True})
+# These contain kwargs supported by both static and shared libraries. These are
+# combined here because a library() call might be shared_library() or
+# static_library() at runtime based on the configuration.
+# FIXME: Find a way to pass that info down here so we can have proper target
+# kwargs checking when specifically using shared_library() or static_library().
+known_lib_kwargs = known_basic_kwargs.copy()
+known_lib_kwargs.update({'version' : True, # Only for shared libs
+                         'soversion' : True, # Only for shared libs
+                         'name_prefix' : True,
+                         'name_suffix' : True,
+                         'vs_module_defs' : True, # Only for shared libs
+                         'pic' : True, # Only for static libs
+                        })
 
 def compilers_are_msvc(compilers):
     """
@@ -516,6 +523,10 @@ class BuildTarget():
                 if not isinstance(name_suffix, str):
                     raise InvalidArguments('Name suffix must be a string.')
                 self.suffix = name_suffix
+        if isinstance(self, StaticLibrary):
+            self.pic = kwargs.get('pic', False)
+            if not isinstance(self.pic, bool):
+                raise InvalidArguments('Argument pic must be boolean')
 
     def get_subdir(self):
         return self.subdir
@@ -831,6 +842,9 @@ class StaticLibrary(BuildTarget):
     def type_suffix(self):
         return "@sta"
 
+    def check_unknown_kwargs(self, kwargs):
+        self.check_unknown_kwargs_int(kwargs, known_lib_kwargs)
+
 class SharedLibrary(BuildTarget):
     def __init__(self, name, subdir, subproject, is_cross, sources, objects, environment, kwargs):
         self.soversion = None
@@ -988,7 +1002,7 @@ class SharedLibrary(BuildTarget):
             self.link_depends.append(path)
 
     def check_unknown_kwargs(self, kwargs):
-        self.check_unknown_kwargs_int(kwargs, known_shlib_kwargs)
+        self.check_unknown_kwargs_int(kwargs, known_lib_kwargs)
 
     def get_import_filename(self):
         """

test cases/common/62 exe static shared/meson.build

@@ -1,6 +1,7 @@
 project('statchain', 'c')
 
 subdir('subdir')
-statlib = static_library('stat', 'stat.c', link_with : shlib)
-exe = executable('prog', 'prog.c', link_with : statlib)
+statlib = static_library('stat', 'stat.c', link_with : shlib, pic : true)
+shlib2 = shared_library('shr2', 'shlib2.c', link_with : statlib)
+exe = executable('prog', 'prog.c', link_with : shlib2)
 test('runtest', exe)

test cases/common/62 exe static shared/prog.c

@@ -1,5 +1,10 @@
+int shlibfunc2();
 int statlibfunc();
 
 int main(int argc, char **argv) {
-    return statlibfunc() == 42 ? 0 : 1;
+    if (statlibfunc() != 42)
+        return 1;
+    if (shlibfunc2() != 24)
+        return 1;
+    return 0;
 }

test cases/common/62 exe static shared/shlib2.c

@@ -0,0 +1,7 @@
+#include "subdir/exports.h"
+
+int statlibfunc(void);
+
+int DLL_PUBLIC shlibfunc2(void) {
+    return statlibfunc() - 18;
+}

test cases/common/62 exe static shared/subdir/exports.h

@@ -0,0 +1,12 @@
+#pragma once
+
+#if defined _WIN32 || defined __CYGWIN__
+  #define DLL_PUBLIC __declspec(dllexport)
+#else
+  #if defined __GNUC__
+    #define DLL_PUBLIC __attribute__ ((visibility("default")))
+  #else
+    #pragma message ("Compiler does not support symbol visibility.")
+    #define DLL_PUBLIC
+  #endif
+#endif

test cases/common/62 exe static shared/subdir/shlib.c

@@ -1,13 +1,4 @@
-#if defined _WIN32 || defined __CYGWIN__
-  #define DLL_PUBLIC __declspec(dllexport)
-#else
-  #if defined __GNUC__
-    #define DLL_PUBLIC __attribute__ ((visibility("default")))
-  #else
-    #pragma message ("Compiler does not support symbol visibility.")
-    #define DLL_PUBLIC
-  #endif
-#endif
+#include "exports.h"
 
 int DLL_PUBLIC shlibfunc() {
     return 42;