Bug 1570515 - Change how build-clang.py consumes subprocess output. r=froydnj

Bug 1546136 wrapped subprocess execution output to capture cmake's, but
at the detriment of other output, and hiding everything unless an error
occurs.

So instead, we only capture the output when the called process is cmake,
and even when it is cmake, we don't pipe stderr at all (since we only
care about cmake's stdout) and we print out stdout as it comes in rather
than later. We then later check the output for hints at the more useful
cmake logs and dump them.

While here, add verbosity to ninja output (which gives the command
lines, rather than generic "Building foo.o" output).

Differential Revision: https://phabricator.services.mozilla.com/D40142

build/build-clang/build-clang.py

@@ -35,27 +35,39 @@ def symlink(source, link_name):
 
 def check_run(args):
     print >> sys.stderr, ' '.join(args)
-    p = subprocess.Popen(args, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
-    # CMake `message(STATUS)` messages, as appearing in failed source code
-    # compiles, appear on stdout, so we only capture that.
-    (out, _) = p.communicate()
-    r = p.returncode
-    if r != 0:
-        cmake_output_re = re.compile("See also \"(.*/CMakeOutput.log)\"")
-        cmake_error_re = re.compile("See also \"(.*/CMakeError.log)\"")
-        output_match = cmake_output_re.search(out)
-        error_match = cmake_error_re.search(out)
+    if args[0] == 'cmake':
+        # CMake `message(STATUS)` messages, as appearing in failed source code
+        # compiles, appear on stdout, so we only capture that.
+        p = subprocess.Popen(args, stdout=subprocess.PIPE)
+        lines = []
+        for line in p.stdout:
+            lines.append(line)
+            sys.stdout.write(line)
+            sys.stdout.flush()
+        r = p.wait()
+        if r != 0:
+            cmake_output_re = re.compile("See also \"(.*/CMakeOutput.log)\"")
+            cmake_error_re = re.compile("See also \"(.*/CMakeError.log)\"")
 
-        print >> sys.stderr, out
+            def find_first_match(re):
+                for l in lines:
+                    match = re.search(l)
+                    if match:
+                        return match
 
-        def dump_file(log):
-            with open(log, 'rb') as f:
-                print >> sys.stderr, "\nContents of", log, "follow\n"
-                print >> sys.stderr, f.read()
-        if output_match:
-            dump_file(output_match.group(1))
-        if error_match:
-            dump_file(error_match.group(1))
+            output_match = find_first_match(cmake_output_re)
+            error_match = find_first_match(cmake_error_re)
+
+            def dump_file(log):
+                with open(log, 'rb') as f:
+                    print >> sys.stderr, "\nContents of", log, "follow\n"
+                    print >> sys.stderr, f.read()
+            if output_match:
+                dump_file(output_match.group(1))
+            if error_match:
+                dump_file(error_match.group(1))
+    else:
+        r = subprocess.call(args)
     assert r == 0
 
 
@@ -96,7 +108,7 @@ def build_package(package_build_dir, cmake_args):
         shutil.rmtree(package_build_dir + "/CMakeFiles")
 
     run_in(package_build_dir, ["cmake"] + cmake_args)
-    run_in(package_build_dir, ["ninja", "install"])
+    run_in(package_build_dir, ["ninja", "install", "-v"])
 
 
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