Add prog/lib dirs from the mingw cross-compiler to PATH

These directories contain DLLs that the executable may need, such as
libstdc++-6.dll, libwinpthread, etc.

mesonbuild/backend/backends.py

@@ -20,7 +20,7 @@ from .. import mlog
 from .. import compilers
 import json
 import subprocess
-from ..mesonlib import MesonException
+from ..mesonlib import MesonException, OrderedSet
 from ..mesonlib import get_compiler_for_source, classify_unity_sources
 from ..mesonlib import File
 from ..compilers import CompilerArgs
@@ -567,17 +567,22 @@ class Backend:
             args.append(d_arg)
         return args
 
-    def get_mingw_extra_paths(self):
-        paths = []
+    def get_mingw_extra_paths(self, target):
+        paths = OrderedSet()
         # The cross bindir
         root = self.environment.cross_info.get_root()
         if root:
-            paths.append(os.path.join(root, 'bin'))
+            paths.add(os.path.join(root, 'bin'))
         # The toolchain bindir
         sys_root = self.environment.cross_info.get_sys_root()
         if sys_root:
-            paths.append(os.path.join(sys_root, 'bin'))
-        return paths
+            paths.add(os.path.join(sys_root, 'bin'))
+        # Get program and library dirs from all target compilers
+        if isinstance(target, build.BuildTarget):
+            for cc in target.compilers.values():
+                paths.update(cc.get_program_dirs())
+                paths.update(cc.get_library_dirs())
+        return list(paths)
 
     def determine_windows_extra_paths(self, target, extra_bdeps, is_cross=False):
         '''On Windows there is no such thing as an rpath.
@@ -600,7 +605,7 @@ class Backend:
             dirseg = os.path.join(self.environment.get_build_dir(), self.get_target_dir(ld))
             result.add(dirseg)
         if is_cross:
-            result.update(self.get_mingw_extra_paths())
+            result.update(self.get_mingw_extra_paths(target))
         return list(result)
 
     def write_benchmark_file(self, datafile):

mesonbuild/compilers/c.py

@@ -45,6 +45,7 @@ from .compilers import (
 
 class CCompiler(Compiler):
     library_dirs_cache = {}
+    program_dirs_cache = {}
 
     def __init__(self, exelist, version, is_cross, exe_wrapper=None, **kwargs):
         # If a child ObjC or CPP class has already set it, don't set it ourselves
@@ -166,11 +167,12 @@ class CCompiler(Compiler):
         env = os.environ.copy()
         env['LC_ALL'] = 'C'
         stdo = Popen_safe(self.exelist + ['--print-search-dirs'], env=env)[1]
+        paths = []
         for line in stdo.split('\n'):
             if line.startswith('libraries:'):
                 libstr = line.split('=', 1)[1]
-                return libstr.split(':')
-        return []
+                paths = [os.path.realpath(p) for p in libstr.split(':')]
+        return paths
 
     def get_library_dirs(self):
         key = tuple(self.exelist)
@@ -178,6 +180,27 @@ class CCompiler(Compiler):
             self.library_dirs_cache[key] = self.get_library_dirs_real()
         return self.library_dirs_cache[key][:]
 
+    def get_program_dirs_real(self):
+        env = os.environ.copy()
+        env['LC_ALL'] = 'C'
+        stdo = Popen_safe(self.exelist + ['--print-search-dirs'], env=env)[1]
+        paths = []
+        for line in stdo.split('\n'):
+            if line.startswith('programs:'):
+                libstr = line.split('=', 1)[1]
+                paths = [os.path.realpath(p) for p in libstr.split(':')]
+        return paths
+
+    def get_program_dirs(self):
+        '''
+        Programs used by the compiler. Also where toolchain DLLs such as
+        libstdc++-6.dll are found with MinGW.
+        '''
+        key = tuple(self.exelist)
+        if key not in self.program_dirs_cache:
+            self.program_dirs_cache[key] = self.get_program_dirs_real()
+        return self.program_dirs_cache[key][:]
+
     def get_pic_args(self):
         return ['-fPIC']
 

mesonbuild/compilers/compilers.py

@@ -1172,13 +1172,27 @@ class ElbrusCompiler(GnuCompiler):
         env = os.environ.copy()
         env['LC_ALL'] = 'C'
         stdo = Popen_safe(self.exelist + ['--print-search-dirs'], env=env)[1]
+        paths = []
         for line in stdo.split('\n'):
             if line.startswith('libraries:'):
                 # lcc does not include '=' in --print-search-dirs output.
                 libstr = line.split(' ', 1)[1]
-                return libstr.split(':')
-        return []
+                paths = [os.path.realpath(p) for p in libstr.split(':')]
+                break
+        return paths
 
+    def get_program_dirs(self):
+        env = os.environ.copy()
+        env['LC_ALL'] = 'C'
+        stdo = Popen_safe(self.exelist + ['--print-search-dirs'], env=env)[1]
+        paths = []
+        for line in stdo.split('\n'):
+            if line.startswith('programs:'):
+                # lcc does not include '=' in --print-search-dirs output.
+                libstr = line.split(' ', 1)[1]
+                paths = [os.path.realpath(p) for p in libstr.split(':')]
+                break
+        return paths
 
 
 class ClangCompiler: