msvc: unify debug filename handling

The MSVC code is extremely confusing, and it turns out it actually
constructs debug (pdb) files names/path independently in separate
places. This is really hard to parse. Instead, refactor it so that the
source of the debug filename is within the target itself
(get_debug_filename). Add a couple of generic methods to retrieve the
full path of the debug filename name in the backend and use that when
needed.

mesonbuild/backend/backends.py

@@ -316,6 +316,20 @@ class Backend:
     def get_target_filename_abs(self, target: T.Union[build.Target, build.CustomTargetIndex]) -> str:
         return os.path.join(self.environment.get_build_dir(), self.get_target_filename(target))
 
+    def get_target_debug_filename(self, target: build.BuildTarget) -> T.Optional[str]:
+        assert isinstance(target, build.BuildTarget), target
+        if target.get_debug_filename():
+            debug_filename = target.get_debug_filename()
+            return os.path.join(self.get_target_dir(target), debug_filename)
+        else:
+            return None
+
+    def get_target_debug_filename_abs(self, target: build.BuildTarget) -> T.Optional[str]:
+        assert isinstance(target, build.BuildTarget), target
+        if not target.get_debug_filename():
+            return None
+        return os.path.join(self.environment.get_build_dir(), self.get_target_debug_filename(target))
+
     def get_source_dir_include_args(self, target: build.BuildTarget, compiler: 'Compiler', *, absolute_path: bool = False) -> T.List[str]:
         curdir = target.get_subdir()
         if absolute_path:

mesonbuild/backend/ninjabackend.py

@@ -2797,16 +2797,18 @@ https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47485'''))
         # this is actually doable, please send patches.
 
         if target.has_pch():
-            tfilename = self.get_target_filename_abs(target)
+            tfilename = self.get_target_debug_filename_abs(target)
+            if not tfilename:
+                tfilename = self.get_target_filename_abs(target)
             return compiler.get_compile_debugfile_args(tfilename, pch=True)
         else:
             return compiler.get_compile_debugfile_args(objfile, pch=False)
 
-    def get_link_debugfile_name(self, linker, target, outname) -> T.Optional[str]:
-        return linker.get_link_debugfile_name(outname)
+    def get_link_debugfile_name(self, linker, target) -> T.Optional[str]:
+        return linker.get_link_debugfile_name(self.get_target_debug_filename(target))
 
-    def get_link_debugfile_args(self, linker, target, outname):
-        return linker.get_link_debugfile_args(outname)
+    def get_link_debugfile_args(self, linker, target):
+        return linker.get_link_debugfile_args(self.get_target_debug_filename(target))
 
     def generate_llvm_ir_compile(self, target, src):
         base_proxy = target.get_options()
@@ -3440,8 +3442,8 @@ https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47485'''))
         commands += linker.get_buildtype_linker_args(target.get_option(OptionKey('buildtype')))
         # Add /DEBUG and the pdb filename when using MSVC
         if target.get_option(OptionKey('debug')):
-            commands += self.get_link_debugfile_args(linker, target, outname)
-            debugfile = self.get_link_debugfile_name(linker, target, outname)
+            commands += self.get_link_debugfile_args(linker, target)
+            debugfile = self.get_link_debugfile_name(linker, target)
             if debugfile is not None:
                 implicit_outs += [debugfile]
         # Add link args specific to this BuildTarget type, such as soname args,

mesonbuild/build.py

@@ -737,6 +737,8 @@ class BuildTarget(Target):
         self.name_prefix_set = False
         self.name_suffix_set = False
         self.filename = 'no_name'
+        # The debugging information file this target will generate
+        self.debug_filename = None
         # The list of all files outputted by this target. Useful in cases such
         # as Vala which generates .vapi and .h besides the compiled output.
         self.outputs = [self.filename]
@@ -1262,6 +1264,14 @@ class BuildTarget(Target):
     def get_filename(self) -> str:
         return self.filename
 
+    def get_debug_filename(self) -> T.Optional[str]:
+        """
+        The name of debuginfo file that will be created by the compiler
+
+        Returns None if the build won't create any debuginfo file
+        """
+        return self.debug_filename
+
     def get_outputs(self) -> T.List[str]:
         return self.outputs
 

mesonbuild/linkers/linkers.py

@@ -1272,8 +1272,7 @@ class VisualStudioLikeLinkerMixin(DynamicLinkerBase):
         return self._apply_prefix('/DLL')
 
     def get_debugfile_name(self, targetfile: str) -> str:
-        basename = targetfile.rsplit('.', maxsplit=1)[0]
-        return basename + '.pdb'
+        return targetfile
 
     def get_debugfile_args(self, targetfile: str) -> T.List[str]:
         return self._apply_prefix(['/DEBUG', '/PDB:' + self.get_debugfile_name(targetfile)])