5 files changed, 23 insertions, 1 deletions
diff --git a/mesonbuild/build.py b/mesonbuild/build.py
index f2a6d9c..df67c8e 100644
--- a/mesonbuild/build.py
+++ b/mesonbuild/build.py
@@ -138,6 +138,19 @@ class Build:
         self.find_overrides = {}
         self.searched_programs = set() # The list of all programs that have been searched for.
 
+    def copy(self):
+        other = Build(self.environment)
+        for k, v in self.__dict__.items():
+            if isinstance(v, (list, dict, set, OrderedDict)):
+                other.__dict__[k] = v.copy()
+            else:
+                other.__dict__[k] = v
+        return other
+
+    def merge(self, other):
+        for k, v in other.__dict__.items():
+            self.__dict__[k] = v
+
     def add_compiler(self, compiler):
         if self.static_linker is None and compiler.needs_static_linker():
             self.static_linker = self.environment.detect_static_linker(compiler)
diff --git a/mesonbuild/interpreter.py b/mesonbuild/interpreter.py
index 66f7f02..8717a83 100644
--- a/mesonbuild/interpreter.py
+++ b/mesonbuild/interpreter.py
@@ -2286,7 +2286,8 @@ external dependencies (including libraries) must go to "dependencies".''')
         with mlog.nested():
             try:
                 mlog.log('\nExecuting subproject', mlog.bold(dirname), '\n')
-                subi = Interpreter(self.build, self.backend, dirname, subdir, self.subproject_dir,
+                new_build = self.build.copy()
+                subi = Interpreter(new_build, self.backend, dirname, subdir, self.subproject_dir,
                                    self.modules, default_options)
                 subi.subprojects = self.subprojects
 
@@ -2312,6 +2313,7 @@ external dependencies (including libraries) must go to "dependencies".''')
         self.subprojects.update(subi.subprojects)
         self.subprojects[dirname] = SubprojectHolder(subi, self.subproject_dir, dirname)
         self.build_def_files += subi.build_def_files
+        self.build.merge(subi.build)
         return self.subprojects[dirname]
 
     def get_option_internal(self, optname):
diff --git a/test cases/common/205 broken subproject/meson.build b/test cases/common/205 broken subproject/meson.build
new file mode 100644
index 0000000..e3a6cae
--- /dev/null
+++ b/test cases/common/205 broken subproject/meson.build
@@ -0,0 +1,2 @@
+project('test broken subproject')
+subproject('broken', required : false)
diff --git a/test cases/common/205 broken subproject/subprojects/broken/broken.c b/test cases/common/205 broken subproject/subprojects/broken/broken.c
new file mode 100644
index 0000000..a9fc4b1
--- /dev/null
+++ b/test cases/common/205 broken subproject/subprojects/broken/broken.c
@@ -0,0 +1 @@
+#error This must not compile
diff --git a/test cases/common/205 broken subproject/subprojects/broken/meson.build b/test cases/common/205 broken subproject/subprojects/broken/meson.build
new file mode 100644
index 0000000..2d64fde
--- /dev/null
+++ b/test cases/common/205 broken subproject/subprojects/broken/meson.build
@@ -0,0 +1,4 @@
+project('broken', 'c')
+
+executable('app', 'broken.c')
+assert(false, 'This subproject must fail')