Add a new compiler object method: has_members (#723)

* Add a new compiler object method: has_members

Identical to 'cc.has_member', except that this takes multiple members
and all of them must exist else it returns false.

This is useful when you want to verify that a structure has all of
a given set of fields. Individually checking each member is horrifying.

* Fix typo in exceptions for has_member(s)

3 files changed, 45 insertions, 11 deletions

diff --git a/mesonbuild/compilers.py b/mesonbuild/compilers.py
index 58444bb..1c6c1da 100644
--- a/mesonbuild/compilers.py
+++ b/mesonbuild/compilers.py
@@ -902,16 +902,21 @@ int main(int argc, char **argv) {
         # directly try to link via main().
         return self.links('int main() {{ {0}; }}'.format('__builtin_' + funcname), env, args)
 
-    def has_member(self, typename, membername, prefix, env, extra_args=None):
+    def has_members(self, typename, membernames, prefix, env, extra_args=None):
         if extra_args is None:
             extra_args = []
-        templ = '''%s
-void bar() {
-    %s foo;
-    foo.%s;
-};
+        templ = '''{0}
+void bar() {{
+    {1} {2};
+    {3}
+}};
 '''
-        return self.compiles(templ % (prefix, typename, membername), env, extra_args)
+        # Create code that accesses all members
+        members = ''
+        for m in membernames:
+            members += 'foo.{};\n'.format(m)
+        code = templ.format(prefix, typename, 'foo', members)
+        return self.compiles(code, env, extra_args)
 
     def has_type(self, typename, prefix, env, extra_args):
         templ = '''%s
diff --git a/mesonbuild/interpreter.py b/mesonbuild/interpreter.py
index 94119f9..c9a81fb 100644
--- a/mesonbuild/interpreter.py
+++ b/mesonbuild/interpreter.py
@@ -590,6 +590,7 @@ class CompilerHolder(InterpreterObject):
                              'run' : self.run_method,
                              'has_function' : self.has_function_method,
                              'has_member' : self.has_member_method,
+                             'has_members' : self.has_members_method,
                              'has_type' : self.has_type_method,
                              'alignment' : self.alignment_method,
                              'version' : self.version_method,
@@ -665,9 +666,10 @@ class CompilerHolder(InterpreterObject):
         membername = args[1]
         prefix = kwargs.get('prefix', '')
         if not isinstance(prefix, str):
-            raise InterpreterException('Prefix argument of has_function must be a string.')
+            raise InterpreterException('Prefix argument of has_member must be a string.')
         extra_args = self.determine_args(kwargs)
-        had = self.compiler.has_member(typename, membername, prefix, self.environment, extra_args)
+        had = self.compiler.has_members(typename, [membername], prefix,
+                                        self.environment, extra_args)
         if had:
             hadtxt = mlog.green('YES')
         else:
@@ -676,6 +678,25 @@ class CompilerHolder(InterpreterObject):
                  '" has member "', mlog.bold(membername), '": ', hadtxt, sep='')
         return had
 
+    def has_members_method(self, args, kwargs):
+        check_stringlist(args)
+        typename = args[0]
+        membernames = args[1:]
+        prefix = kwargs.get('prefix', '')
+        if not isinstance(prefix, str):
+            raise InterpreterException('Prefix argument of has_members must be a string.')
+        extra_args = self.determine_args(kwargs)
+        had = self.compiler.has_members(typename, membernames, prefix,
+                                        self.environment, extra_args)
+        if had:
+            hadtxt = mlog.green('YES')
+        else:
+            hadtxt = mlog.red('NO')
+        members = mlog.bold(', '.join(['"{}"'.format(m) for m in membernames]))
+        mlog.log('Checking whether type "', mlog.bold(typename),
+                 '" has members ', members, ': ', hadtxt, sep='')
+        return had
+
     def has_function_method(self, args, kwargs):
         if len(args) != 1:
             raise InterpreterException('Has_function takes exactly one argument.')
diff --git a/test cases/common/44 has member/meson.build b/test cases/common/44 has member/meson.build
index fa01877..e60aeb3 100644
--- a/test cases/common/44 has member/meson.build
+++ b/test cases/common/44 has member/meson.build
@@ -3,9 +3,17 @@ project('has member', 'c')
 cc = meson.get_compiler('c')
 
 if not cc.has_member('struct tm', 'tm_sec', prefix : '#include<time.h>')
-  error('Did not detect member that exists.')
+  error('Did not detect member of "struct tm" that exists: "tm_sec"')
 endif
 
 if cc.has_member('struct tm', 'tm_nonexistent', prefix : '#include<time.h>')
-  error('Not existing member found.')
+  error('Not existing member "tm_nonexistent" found.')
+endif
+
+if not cc.has_members('struct tm', 'tm_sec', 'tm_min', prefix : '#include<time.h>')
+  error('Did not detect members of "struct tm" that exist: "tm_sec" "tm_min"')
+endif
+
+if cc.has_members('struct tm', 'tm_sec', 'tm_nonexistent2', prefix : '#include<time.h>')
+  error('Not existing member "tm_nonexistent2" found.')
 endif