Add both_libraries() to build both shared and static libraries

Also support default_library='both' to make library() build both shared
and static libraries.

Closes #484

8 files changed, 140 insertions, 9 deletions

diff --git a/docs/markdown/Reference-manual.md b/docs/markdown/Reference-manual.md
index 5109b25..d98fc19 100644
--- a/docs/markdown/Reference-manual.md
+++ b/docs/markdown/Reference-manual.md
@@ -112,6 +112,24 @@ run. The behavior of this function is identical to `test` with the
 exception that there is no `is_parallel` keyword, because benchmarks
 are never run in parallel.
 
+### both_libraries()
+
+``` meson
+    buildtarget both_libraries(library_name, list_of_sources, ...)
+```
+
+Builds both a static and shared library with the given sources. Positional and
+keyword arguments are otherwise the same as for [`library`](#library). Source
+files will be compiled only once and object files will be reused to build both
+shared and static libraries, unless `b_staticpic` user option or `pic` argument
+are set to false in which case sources will be compiled twice.
+
+The returned [buildtarget](#build-target-object) always represents the shared
+library. In addition it supports the following extra methods:
+
+- `get_shared_lib()` returns the shared library build target
+- `get_static_lib()` returns the static library build target
+
 ### build_target()
 
 Creates a build target whose type can be set dynamically with the
@@ -885,10 +903,11 @@ dropped. That means that `join_paths('foo', '/bar')` returns `/bar`.
     buildtarget library(library_name, list_of_sources, ...)
 ```
 
-Builds a library that is either static or shared depending on the
-value of `default_library` user option. You should use this instead of
-[`shared_library`](#shared_library) or
-[`static_library`](#static_library) most of the time. This allows you
+Builds a library that is either static, shared or both depending on the value of
+`default_library` user option. You should use this instead of
+[`shared_library`](#shared_library),
+[`static_library`](#static_library) or
+[`both_libraries`](#both_libraries) most of the time. This allows you
 to toggle your entire project (including subprojects) from shared to
 static with only one option.
 
@@ -911,7 +930,8 @@ The keyword arguments for this are the same as for [`executable`](#executable) w
   libraries. Defaults to `dylib` for shared libraries and `rlib` for
   static libraries.
 
-`static_library` and `shared_library` also accept these keyword arguments.
+`static_library`, `shared_library` and `both_libraries` also accept these keyword
+arguments.
 
 ### message()
 
@@ -1670,7 +1690,8 @@ These are objects returned by the [functions listed above](#functions).
 ### `build target` object
 
 A build target is either an [executable](#executable),
-[shared](#shared_library), [static library](#static_library) or
+[shared library](#shared_library), [static library](#static_library),
+[both shared and static library](#both_libraries) or
 [shared module](#shared_module).
 
 - `extract_all_objects()` is same as `extract_objects` but returns all
diff --git a/docs/markdown/snippets/both-libraries.md b/docs/markdown/snippets/both-libraries.md
new file mode 100644
index 0000000..1632f63
--- /dev/null
+++ b/docs/markdown/snippets/both-libraries.md
@@ -0,0 +1,9 @@
+## Building both shared and static libraries
+
+A new function `both_libraries()` has been added to build both shared and static
+libraries at the same time. Source files will be compiled only once and object
+files will be reused to build both shared and static libraries, unless
+`b_staticpic` user option or `pic` argument are set to false in which case
+sources will be compiled twice.
+
+The returned `buildtarget` object always represents the shared library.
diff --git a/mesonbuild/coredata.py b/mesonbuild/coredata.py
index 993effc..88d007a 100644
--- a/mesonbuild/coredata.py
+++ b/mesonbuild/coredata.py
@@ -422,7 +422,7 @@ builtin_options = {
     'werror':          [UserBooleanOption, 'Treat warnings as errors.', False],
     'warning_level':   [UserComboOption, 'Compiler warning level to use.', ['1', '2', '3'], '1'],
     'layout':          [UserComboOption, 'Build directory layout.', ['mirror', 'flat'], 'mirror'],
-    'default_library': [UserComboOption, 'Default library type.', ['shared', 'static'], 'shared'],
+    'default_library': [UserComboOption, 'Default library type.', ['shared', 'static', 'both'], 'shared'],
     'backend':         [UserComboOption, 'Backend to use.', backendlist, 'ninja'],
     'stdsplit':        [UserBooleanOption, 'Split stdout and stderr in test logs.', True],
     'errorlogs':       [UserBooleanOption, "Whether to print the logs from failing tests.", True],
diff --git a/mesonbuild/interpreter.py b/mesonbuild/interpreter.py
index 6bd0b97..88565af 100644
--- a/mesonbuild/interpreter.py
+++ b/mesonbuild/interpreter.py
@@ -608,6 +608,29 @@ class SharedLibraryHolder(BuildTargetHolder):
         # Set to True only when called from self.func_shared_lib().
         target.shared_library_only = False
 
+class BothLibrariesHolder(BuildTargetHolder):
+    def __init__(self, shared_holder, static_holder, interp):
+        # FIXME: This build target always represents the shared library, but
+        # that should be configurable.
+        super().__init__(shared_holder.held_object, interp)
+        self.shared_holder = shared_holder
+        self.static_holder = static_holder
+        self.methods.update({'get_shared_lib': self.get_shared_lib_method,
+                             'get_static_lib': self.get_static_lib_method,
+                             })
+
+    def __repr__(self):
+        r = '<{} {}: {}, {}: {}>'
+        h1 = self.shared_holder.held_object
+        h2 = self.static_holder.held_object
+        return r.format(self.__class__.__name__, h1.get_id(), h1.filename, h2.get_id(), h2.filename)
+
+    def get_shared_lib_method(self, args, kwargs):
+        return self.shared_holder
+
+    def get_static_lib_method(self, args, kwargs):
+        return self.static_holder
+
 class SharedModuleHolder(BuildTargetHolder):
     def __init__(self, target, interp):
         super().__init__(target, interp)
@@ -1458,6 +1481,7 @@ permitted_kwargs = {'add_global_arguments': {'language'},
                     'shared_library': build.known_shlib_kwargs,
                     'shared_module': build.known_shmod_kwargs,
                     'static_library': build.known_stlib_kwargs,
+                    'both_libraries': known_library_kwargs,
                     'library': known_library_kwargs,
                     'subdir': {'if_found'},
                     'subproject': {'version', 'default_options'},
@@ -1559,6 +1583,7 @@ class Interpreter(InterpreterBase):
                            'shared_library': self.func_shared_lib,
                            'shared_module': self.func_shared_module,
                            'static_library': self.func_static_lib,
+                           'both_libraries': self.func_both_lib,
                            'test': self.func_test,
                            'vcs_tag': self.func_vcs_tag,
                            'subdir_done': self.func_subdir_done,
@@ -2492,6 +2517,10 @@ root and issuing %s.
         holder.held_object.shared_library_only = True
         return holder
 
+    @permittedKwargs(permitted_kwargs['both_libraries'])
+    def func_both_lib(self, node, args, kwargs):
+        return self.build_both_libraries(node, args, kwargs)
+
     @permittedKwargs(permitted_kwargs['shared_module'])
     def func_shared_module(self, node, args, kwargs):
         return self.build_target(node, args, kwargs, SharedModuleHolder)
@@ -2515,6 +2544,8 @@ root and issuing %s.
             return self.build_target(node, args, kwargs, SharedLibraryHolder)
         elif target_type == 'static_library':
             return self.build_target(node, args, kwargs, StaticLibraryHolder)
+        elif target_type == 'both_libraries':
+            return self.build_both_libraries(node, args, kwargs)
         elif target_type == 'library':
             return self.build_library(node, args, kwargs)
         elif target_type == 'jar':
@@ -3171,10 +3202,40 @@ different subdirectory.
         if idname not in self.coredata.target_guids:
             self.coredata.target_guids[idname] = str(uuid.uuid4()).upper()
 
+    def build_both_libraries(self, node, args, kwargs):
+        shared_holder = self.build_target(node, args, kwargs, SharedLibraryHolder)
+
+        # Check if user forces non-PIC static library.
+        pic = True
+        if 'pic' in kwargs:
+            pic = kwargs['pic']
+        elif 'b_staticpic' in self.environment.coredata.base_options:
+            pic = self.environment.coredata.base_options['b_staticpic'].value
+
+        if pic:
+            # Exclude sources from args and kwargs to avoid building them twice
+            static_args = [args[0]]
+            static_kwargs = kwargs.copy()
+            static_kwargs['sources'] = []
+            static_kwargs['objects'] = shared_holder.held_object.extract_all_objects()
+        else:
+            static_args = args
+            static_kwargs = kwargs
+
+        static_holder = self.build_target(node, static_args, static_kwargs, StaticLibraryHolder)
+
+        return BothLibrariesHolder(shared_holder, static_holder, self)
+
     def build_library(self, node, args, kwargs):
-        if self.coredata.get_builtin_option('default_library') == 'shared':
+        default_library = self.coredata.get_builtin_option('default_library')
+        if default_library == 'shared':
             return self.build_target(node, args, kwargs, SharedLibraryHolder)
-        return self.build_target(node, args, kwargs, StaticLibraryHolder)
+        elif default_library == 'static':
+            return self.build_target(node, args, kwargs, StaticLibraryHolder)
+        elif default_library == 'both':
+            return self.build_both_libraries(node, args, kwargs)
+        else:
+            raise InterpreterException('Unknown default_library value: %s.', default_library)
 
     def build_target(self, node, args, kwargs, targetholder):
         if not args:
diff --git a/test cases/common/189 bothlibraries/libfile.c b/test cases/common/189 bothlibraries/libfile.c
new file mode 100644
index 0000000..085ef3b
--- /dev/null
+++ b/test cases/common/189 bothlibraries/libfile.c
@@ -0,0 +1,7 @@
+#include "mylib.h"
+
+DO_EXPORT int retval = 42;
+
+DO_EXPORT int func() {
+    return retval;
+}
diff --git a/test cases/common/189 bothlibraries/main.c b/test cases/common/189 bothlibraries/main.c
new file mode 100644
index 0000000..03a8e02
--- /dev/null
+++ b/test cases/common/189 bothlibraries/main.c
@@ -0,0 +1,8 @@
+#include "mylib.h"
+
+DO_IMPORT int func();
+DO_IMPORT int retval;
+
+int main(int argc, char **arg) {
+    return func() == retval ? 0 : 1;
+}
diff --git a/test cases/common/189 bothlibraries/meson.build b/test cases/common/189 bothlibraries/meson.build
new file mode 100644
index 0000000..3a13d62
--- /dev/null
+++ b/test cases/common/189 bothlibraries/meson.build
@@ -0,0 +1,12 @@
+project('both libraries linking test', 'c')
+
+both_libs = both_libraries('mylib', 'libfile.c')
+exe_shared = executable('prog-shared', 'main.c', link_with : both_libs.get_shared_lib())
+exe_static = executable('prog-static', 'main.c',
+                        c_args : ['-DSTATIC_COMPILATION'],
+                        link_with : both_libs.get_static_lib())
+exe_both = executable('prog-both', 'main.c', link_with : both_libs)
+
+test('runtest-shared', exe_shared)
+test('runtest-static', exe_static)
+test('runtest-both', exe_both)
diff --git a/test cases/common/189 bothlibraries/mylib.h b/test cases/common/189 bothlibraries/mylib.h
new file mode 100644
index 0000000..1038a01
--- /dev/null
+++ b/test cases/common/189 bothlibraries/mylib.h
@@ -0,0 +1,13 @@
+#pragma once
+
+#ifdef _WIN32
+  #ifdef STATIC_COMPILATION
+    #define DO_IMPORT extern
+  #else
+    #define DO_IMPORT __declspec(dllimport)
+  #endif
+  #define DO_EXPORT __declspec(dllexport)
+#else
+  #define DO_IMPORT extern
+  #define DO_EXPORT
+#endif