ninjabackend: List PDBs in output list for targets

This is more correct, and forces the target(s) to be rebuilt if the
PDB files are missing. Increases the minimum required Ninja to 1.7,
which is available in Ubuntu 16.04 under backports.

We can't do the same for import libraries, because it is impossible
for us to know at configure time whether or not an import library will
be generated for a given DLL.

6 files changed, 51 insertions, 20 deletions

diff --git a/docs/markdown/snippets/ninja_version_bump.md b/docs/markdown/snippets/ninja_version_bump.md
new file mode 100644
index 0000000..9c5f6e8
--- /dev/null
+++ b/docs/markdown/snippets/ninja_version_bump.md
@@ -0,0 +1,10 @@
+## Ninja version requirement bumped to 1.7
+
+Meson now uses the [Implicit outputs](https://ninja-build.org/manual.html#ref_outputs)
+feature of Ninja for some types of targets that have multiple outputs which may
+not be listed on the command-line. This feature requires Ninja 1.7+.
+
+Note that the latest version of [Ninja available in Ubuntu 16.04](https://packages.ubuntu.com/search?keywords=ninja-build&searchon=names&suite=xenial-backports&section=all)
+(the oldest Ubuntu LTS at the time of writing) is 1.7.1. If your distro does
+not ship with a new-enough Ninja, you can download the latest release from
+Ninja's GitHub page: https://github.com/ninja-build/ninja/releases
diff --git a/mesonbuild/backend/ninjabackend.py b/mesonbuild/backend/ninjabackend.py
index bccc445..11fd92f 100644
--- a/mesonbuild/backend/ninjabackend.py
+++ b/mesonbuild/backend/ninjabackend.py
@@ -120,7 +120,8 @@ class NinjaRule:
         outfile.write('\n')
 
 class NinjaBuildElement:
-    def __init__(self, all_outputs, outfilenames, rule, infilenames):
+    def __init__(self, all_outputs, outfilenames, rule, infilenames, implicit_outs=None):
+        self.implicit_outfilenames = implicit_outs or []
         if isinstance(outfilenames, str):
             self.outfilenames = [outfilenames]
         else:
@@ -155,9 +156,12 @@ class NinjaBuildElement:
 
     def write(self, outfile):
         self.check_outputs()
-        line = 'build %s: %s %s' % (' '.join([ninja_quote(i, True) for i in self.outfilenames]),
-                                    self.rule,
-                                    ' '.join([ninja_quote(i, True) for i in self.infilenames]))
+        ins = ' '.join([ninja_quote(i, True) for i in self.infilenames])
+        outs = ' '.join([ninja_quote(i, True) for i in self.outfilenames])
+        implicit_outs = ' '.join([ninja_quote(i, True) for i in self.implicit_outfilenames])
+        if implicit_outs:
+            implicit_outs = ' | ' + implicit_outs
+        line = 'build {}{}: {} {}'.format(outs, implicit_outs, self.rule, ins)
         if len(self.deps) > 0:
             line += ' | ' + ' '.join([ninja_quote(x, True) for x in self.deps])
         if len(self.orderdeps) > 0:
@@ -1947,6 +1951,9 @@ https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47485'''))
         else:
             return compiler.get_compile_debugfile_args(objfile, pch=False)
 
+    def get_link_debugfile_name(self, linker, target, outname):
+        return linker.get_link_debugfile_name(outname)
+
     def get_link_debugfile_args(self, linker, target, outname):
         return linker.get_link_debugfile_args(outname)
 
@@ -2449,6 +2456,7 @@ https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47485'''))
     def generate_link(self, target, outname, obj_list, linker, extra_args=None, stdlib_args=None):
         extra_args = extra_args if extra_args is not None else []
         stdlib_args = stdlib_args if stdlib_args is not None else []
+        implicit_outs = []
         if isinstance(target, build.StaticLibrary):
             linker_base = 'STATIC'
         else:
@@ -2484,6 +2492,9 @@ https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47485'''))
         # Add /DEBUG and the pdb filename when using MSVC
         if self.get_option_for_target('debug', target):
             commands += self.get_link_debugfile_args(linker, target, outname)
+            debugfile = self.get_link_debugfile_name(linker, target, outname)
+            if debugfile is not None:
+                implicit_outs += [debugfile]
         # Add link args specific to this BuildTarget type, such as soname args,
         # PIC, import library generation, etc.
         commands += self.get_target_type_link_args(target, linker)
@@ -2572,7 +2583,7 @@ https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47485'''))
         dep_targets.extend([self.get_dependency_filename(t) for t in dependencies])
         dep_targets.extend([self.get_dependency_filename(t)
                             for t in target.link_depends])
-        elem = NinjaBuildElement(self.all_outputs, outname, linker_rule, obj_list)
+        elem = NinjaBuildElement(self.all_outputs, outname, linker_rule, obj_list, implicit_outs=implicit_outs)
         elem.add_dep(dep_targets + custom_target_libraries)
         elem.add_item('LINK_ARGS', commands)
         return elem
diff --git a/mesonbuild/compilers/compilers.py b/mesonbuild/compilers/compilers.py
index e8e72cf..67686a9 100644
--- a/mesonbuild/compilers/compilers.py
+++ b/mesonbuild/compilers/compilers.py
@@ -976,6 +976,9 @@ class Compiler:
     def get_compile_debugfile_args(self, rel_obj, **kwargs):
         return []
 
+    def get_link_debugfile_name(self, targetfile: str) -> str:
+        return self.linker.get_debugfile_name(targetfile)
+
     def get_link_debugfile_args(self, targetfile: str) -> T.List[str]:
         return self.linker.get_debugfile_args(targetfile)
 
diff --git a/mesonbuild/environment.py b/mesonbuild/environment.py
index 554d79b..a928248 100644
--- a/mesonbuild/environment.py
+++ b/mesonbuild/environment.py
@@ -140,11 +140,11 @@ def find_coverage_tools():
 
     return gcovr_exe, gcovr_new_rootdir, lcov_exe, genhtml_exe
 
-def detect_ninja(version: str = '1.5', log: bool = False) -> str:
+def detect_ninja(version: str = '1.7', log: bool = False) -> str:
     r = detect_ninja_command_and_version(version, log)
     return r[0] if r else None
 
-def detect_ninja_command_and_version(version: str = '1.5', log: bool = False) -> (str, str):
+def detect_ninja_command_and_version(version: str = '1.7', log: bool = False) -> (str, str):
     env_ninja = os.environ.get('NINJA', None)
     for n in [env_ninja] if env_ninja else ['ninja', 'ninja-build', 'samu']:
         try:
diff --git a/mesonbuild/linkers.py b/mesonbuild/linkers.py
index 9781813..b1d80c3 100644
--- a/mesonbuild/linkers.py
+++ b/mesonbuild/linkers.py
@@ -75,6 +75,9 @@ class StaticLinker:
     def native_args_to_unix(cls, args: T.List[str]) -> T.List[str]:
         return args[:]
 
+    def get_link_debugfile_name(self, targetfile: str) -> str:
+        return None
+
     def get_link_debugfile_args(self, targetfile: str) -> T.List[str]:
         # Static libraries do not have PDB files
         return []
@@ -305,6 +308,10 @@ class DynamicLinker(metaclass=abc.ABCMeta):
         m = 'Language {} does not support has_multi_link_arguments.'
         raise mesonlib.EnvironmentException(m.format(self.id))
 
+    def get_debugfile_name(self, targetfile: str) -> str:
+        '''Name of debug file written out (see below)'''
+        return None
+
     def get_debugfile_args(self, targetfile: str) -> T.List[str]:
         """Some compilers (MSVC) write debug into a separate file.
 
@@ -812,10 +819,12 @@ class VisualStudioLikeLinkerMixin:
     def get_std_shared_lib_args(self) -> T.List[str]:
         return self._apply_prefix('/DLL')
 
+    def get_debugfile_name(self, targetfile: str) -> str:
+        basename = targetfile.rsplit('.', maxsplit=1)[0]
+        return basename + '.pdb'
+
     def get_debugfile_args(self, targetfile: str) -> T.List[str]:
-        pdbarr = targetfile.split('.')[:-1]
-        pdbarr += ['pdb']
-        return self._apply_prefix(['/DEBUG', '/PDB:' + '.'.join(pdbarr)])
+        return self._apply_prefix(['/DEBUG', '/PDB:' + self.get_debugfile_name(targetfile)])
 
     def get_link_whole_for(self, args: T.List[str]) -> T.List[str]:
         # Only since VS2015
diff --git a/run_tests.py b/run_tests.py
index 535c792..3237e85 100755
--- a/run_tests.py
+++ b/run_tests.py
@@ -45,17 +45,15 @@ if 'CI' in os.environ:
     NINJA_CMD = 'ninja'
 else:
     # Look for 1.9 to see if https://github.com/ninja-build/ninja/issues/1219
-    # is fixed, else require 1.6 for -w dupbuild=err
-    for v in ('1.9', '1.6'):
-        NINJA_CMD = detect_ninja(v)
-        if NINJA_CMD is not None:
-            if mesonlib.version_compare(v, '>=1.9'):
-                NINJA_1_9_OR_NEWER = True
-            else:
-                mlog.warning('Found ninja <1.9, tests will run slower', once=True)
-            break
+    # is fixed
+    NINJA_CMD = detect_ninja('1.9')
+    if NINJA_CMD is not None:
+        NINJA_1_9_OR_NEWER = True
+    else:
+        mlog.warning('Found ninja <1.9, tests will run slower', once=True)
+        NINJA_CMD = detect_ninja()
 if NINJA_CMD is None:
-    raise RuntimeError('Could not find Ninja v1.6 or newer')
+    raise RuntimeError('Could not find Ninja v1.7 or newer')
 
 def guess_backend(backend, msbuild_exe: str):
     # Auto-detect backend if unspecified