Merge pull request #542 from mesonbuild/ownstdlib

Build transparently with a custom standard library

13 files changed, 153 insertions, 0 deletions

diff --git a/cross/ownstdlib.txt b/cross/ownstdlib.txt
new file mode 100644
index 0000000..46e99f7
--- /dev/null
+++ b/cross/ownstdlib.txt
@@ -0,0 +1,13 @@
+# This is a setup for compiling a program that runs natively
+# but uses a custom std lib. This test will only work on
+# x86_64.
+
+[target_machine]
+system = 'linux'
+cpu_family = 'x86_64'
+cpu = 'x86_64'
+endian = 'little'
+
+[properties]
+
+c_stdlib = ['mylibc', 'mylibc_dep'] # Subproject name, dependency name
diff --git a/manual tests/9 nostdlib/meson.build b/manual tests/9 nostdlib/meson.build
new file mode 100644
index 0000000..3ef743e
--- /dev/null
+++ b/manual tests/9 nostdlib/meson.build
@@ -0,0 +1,10 @@
+project('own libc', 'c')
+
+# A simple project that uses its own libc.
+
+# Note that we don't need to specify anything, the flags to use
+# stdlib come from the cross file.
+
+exe = executable('selfcontained', 'prog.c')
+
+test('standalone test', exe)
diff --git a/manual tests/9 nostdlib/prog.c b/manual tests/9 nostdlib/prog.c
new file mode 100644
index 0000000..9414bce
--- /dev/null
+++ b/manual tests/9 nostdlib/prog.c
@@ -0,0 +1,7 @@
+
+#include<stdio.h>
+
+int main() {
+  const char *message = "Hello without stdlib.\n";
+  return simple_print(message, simple_strlen(message));
+}
diff --git a/manual tests/9 nostdlib/subprojects/mylibc/libc.c b/manual tests/9 nostdlib/subprojects/mylibc/libc.c
new file mode 100644
index 0000000..67261cb
--- /dev/null
+++ b/manual tests/9 nostdlib/subprojects/mylibc/libc.c
@@ -0,0 +1,35 @@
+/* Do not use this as the basis of your own libc.
+ * The code is probably unoptimal or wonky, as I
+ * had no prior experience with this, but instead
+ * just fiddled with the code until it worked.
+ */
+
+#include<stdio.h>
+
+#define STDOUT 1
+#define SYS_WRITE 4
+
+int simple_print(const char *msg, const long bufsize) {
+  int count;
+  long total_written = 0;
+  while(total_written < bufsize) {
+    asm(
+        "int $0x80\n\t"
+        : "=a"(count)
+        : "0"(SYS_WRITE), "b"(STDOUT), "c"(msg+total_written), "d"(bufsize-total_written)
+        :);
+    if(count == 0) {
+      return 1;
+    }
+    total_written += count;
+  }
+  return 0;
+}
+
+int simple_strlen(const char *str) {
+  int len = 0;
+  while(str[len] != '\0') {
+    len++;
+  }
+  return len;
+}
diff --git a/manual tests/9 nostdlib/subprojects/mylibc/meson.build b/manual tests/9 nostdlib/subprojects/mylibc/meson.build
new file mode 100644
index 0000000..aa0184e
--- /dev/null
+++ b/manual tests/9 nostdlib/subprojects/mylibc/meson.build
@@ -0,0 +1,11 @@
+project('own libc', 'c')
+
+# A very simple libc implementation
+
+# Do not specify -nostdlib & co. They come from cross specifications.
+
+libc = static_library('c', 'libc.c', 'stubstart.s')
+
+mylibc_dep = declare_dependency(link_with : libc,
+  include_directories : include_directories('.')
+)
diff --git a/manual tests/9 nostdlib/subprojects/mylibc/stdio.h b/manual tests/9 nostdlib/subprojects/mylibc/stdio.h
new file mode 100644
index 0000000..c3f8f56
--- /dev/null
+++ b/manual tests/9 nostdlib/subprojects/mylibc/stdio.h
@@ -0,0 +1,5 @@
+#pragma once
+
+int simple_print(const char *msg, const long bufsize);
+
+int simple_strlen(const char *str);
diff --git a/manual tests/9 nostdlib/subprojects/mylibc/stubstart.s b/manual tests/9 nostdlib/subprojects/mylibc/stubstart.s
new file mode 100644
index 0000000..0a6d972
--- /dev/null
+++ b/manual tests/9 nostdlib/subprojects/mylibc/stubstart.s
@@ -0,0 +1,8 @@
+.globl _start
+
+_start:
+
+    call main
+    movl %eax, %ebx
+    movl $1, %eax
+    int $0x80
diff --git a/mesonbuild/backend/backends.py b/mesonbuild/backend/backends.py
index 7c6caa6..d4a0f99 100644
--- a/mesonbuild/backend/backends.py
+++ b/mesonbuild/backend/backends.py
@@ -286,6 +286,7 @@ class Backend():
 
     def generate_basic_compiler_args(self, target, compiler):
         commands = []
+        commands += self.get_cross_stdlib_args(target, compiler)
         commands += compiler.get_always_args()
         commands += compiler.get_warn_args(self.environment.coredata.get_builtin_option('warning_level'))
         commands += compiler.get_option_compile_args(self.environment.coredata.compiler_options)
diff --git a/mesonbuild/backend/ninjabackend.py b/mesonbuild/backend/ninjabackend.py
index bd6f4db..4b85565 100644
--- a/mesonbuild/backend/ninjabackend.py
+++ b/mesonbuild/backend/ninjabackend.py
@@ -1394,6 +1394,13 @@ rule FORTRAN_DEP_HACK
                 mod_files.append(os.path.join(dirname, mod_name))
         return mod_files
 
+    def get_cross_stdlib_args(self, target, compiler):
+        if not target.is_cross:
+            return []
+        if self.environment.cross_info.has_stdlib(compiler.language):
+            return []
+        return compiler.get_no_stdinc_args()
+
     def generate_single_compile(self, target, outfile, src, is_generated=False, header_deps=[], order_deps=[]):
         if(isinstance(src, str) and src.endswith('.h')):
             raise RuntimeError('Fug')
@@ -1599,6 +1606,13 @@ rule FORTRAN_DEP_HACK
             elem.add_item('CROSS', '--cross-host=' + self.environment.cross_info.config['host_machine']['system'])
         elem.write(outfile)
 
+    def get_cross_stdlib_link_args(self, target, linker):
+        if isinstance(target, build.StaticLibrary) or not target.is_cross:
+            return []
+        if not self.environment.cross_info.has_stdlib(linker.language):
+            return []
+        return linker.get_no_stdlib_link_args()
+
     def generate_link(self, target, outfile, outname, obj_list, linker, extra_args=[]):
         if isinstance(target, build.StaticLibrary):
             linker_base = 'STATIC'
@@ -1612,6 +1626,7 @@ rule FORTRAN_DEP_HACK
         linker_rule = linker_base + crstr + '_LINKER'
         abspath = os.path.join(self.environment.get_build_dir(), target.subdir)
         commands = []
+        commands += self.get_cross_stdlib_link_args(target, linker)
         commands += linker.get_linker_always_args()
         if not isinstance(target, build.StaticLibrary):
             commands += compilers.get_base_link_args(self.environment.coredata.base_options,
diff --git a/mesonbuild/build.py b/mesonbuild/build.py
index 1e9a1bb..9de556c 100644
--- a/mesonbuild/build.py
+++ b/mesonbuild/build.py
@@ -101,6 +101,7 @@ class Build:
         self.install_dirs = []
         self.dep_manifest_name = None
         self.dep_manifest = {}
+        self.cross_stdlibs = {}
 
     def has_language(self, language):
         for i in self.compilers:
diff --git a/mesonbuild/compilers.py b/mesonbuild/compilers.py
index 27a49a7..241192e 100644
--- a/mesonbuild/compilers.py
+++ b/mesonbuild/compilers.py
@@ -311,6 +311,12 @@ class CCompiler(Compiler):
     def get_always_args(self):
         return []
 
+    def get_no_stdinc_args(self):
+        return ['-nostdinc']
+
+    def get_no_stdlib_link_args(self):
+        return ['-nostdlib']
+
     def get_warn_args(self, level):
         return self.warn_args[level]
 
diff --git a/mesonbuild/environment.py b/mesonbuild/environment.py
index 41e8531..5096320 100644
--- a/mesonbuild/environment.py
+++ b/mesonbuild/environment.py
@@ -759,6 +759,12 @@ class CrossBuildInfo():
     def has_target(self):
         return 'target_machine' in self.config
 
+    def has_stdlib(self, language):
+        return language + '_stdlib' in self.config['properties']
+
+    def get_stdlib(self, language):
+        return self.config['properties'][language + '_stdlib']
+
     # Wehn compiling a cross compiler we use the native compiler for everything.
     # But not when cross compiling a cross compiler.
     def need_cross_compiler(self):
diff --git a/mesonbuild/interpreter.py b/mesonbuild/interpreter.py
index fb3e601..f269c2f 100644
--- a/mesonbuild/interpreter.py
+++ b/mesonbuild/interpreter.py
@@ -1078,6 +1078,22 @@ class Interpreter():
         if not isinstance(first, mparser.FunctionNode) or first.func_name != 'project':
             raise InvalidCode('First statement must be a call to project')
 
+    def check_cross_stdlibs(self):
+        if self.build.environment.is_cross_build():
+            cross_info = self.build.environment.cross_info
+            for c in self.build.cross_compilers:
+                l = c.language
+                try:
+                    di = mesonlib.stringlistify(cross_info.get_stdlib(l))
+                    if len(di) != 2:
+                        raise InterpreterException('Stdlib definition for %s should have exactly two elements.' \
+                                                   % l)
+                    projname, depname = di
+                    subproj = self.do_subproject(projname, {})
+                    self.build.cross_stdlibs[l] = subproj.get_variable_method([depname], {})
+                except KeyError as e:
+                    pass
+
     def run(self):
         self.evaluate_codeblock(self.ast)
         mlog.log('Build targets in project:', mlog.bold(str(len(self.build.targets))))
@@ -1412,6 +1428,8 @@ class Interpreter():
         if 'vala' in langs:
             if not 'c' in langs:
                 raise InterpreterException('Compiling Vala requires C. Add C to your project languages and rerun Meson.')
+        if not self.is_subproject():
+            self.check_cross_stdlibs()
 
     @stringArgs
     def func_add_languages(self, node, args, kwargs):
@@ -1983,11 +2001,28 @@ class Interpreter():
             mlog.debug('Unknown target type:', str(targetholder))
             raise RuntimeError('Unreachable code')
         target = targetclass(name, self.subdir, self.subproject, is_cross, sources, objs, self.environment, kwargs)
+        if is_cross:
+            self.add_cross_stdlib_info(target)
         l = targetholder(target, self)
         self.add_target(name, l.held_object)
         self.global_args_frozen = True
         return l
 
+    def get_used_languages(self, target):
+        result = {}
+        for i in target.sources:
+            for c in self.build.compilers:
+                if c.can_compile(i):
+                    result[c.language] = True
+                    break
+        return result
+
+    def add_cross_stdlib_info(self, target):
+        for l in self.get_used_languages(target):
+            if self.environment.cross_info.has_stdlib(l) and \
+                self.subproject != self.environment.cross_info.get_stdlib(l)[0]:
+                target.add_external_deps(self.build.cross_stdlibs[l])
+
     def check_sources_exist(self, subdir, sources):
         for s in sources:
             if not isinstance(s, str):