Bug 1962300 - Provide support for unavailable symbols as weak symbols r=m_kato,gfx-reviewers,firefox-build-system-reviewers,glandium,necko-reviewers,geckoview-reviewers,cubeb-reviewers,valentin,padenot,jnicol

Compiler support make it possible to detect missing checks at compile
time, so it's relatively safe, as described in https://developer.android.com/ndk/guides/using-newer-apis

It's now applied globally on android.

Deactivate the associate compiler warning on cubeb as it otherwise
throws warning for type computations.

Differential Revision: https://phabricator.services.mozilla.com/D246803

build/moz.configure/android-ndk.configure

@@ -274,11 +274,29 @@ def extra_toolchain_flags(android_sysroot, toolchain_dir):
 
 @depends(extra_toolchain_flags)
 def android_flags(extra_toolchain_flags):
+    wead_symbols_defines = [
+        "-D__ANDROID_UNAVAILABLE_SYMBOLS_ARE_WEAK__",
+    ]
+    weak_symbols_flags = wead_symbols_defines + [
+        "-Werror=unguarded-availability",
+    ]
     return namespace(
-        cflags=extra_toolchain_flags + ["-fno-short-enums"],
+        cflags=extra_toolchain_flags
-        cxxflags=extra_toolchain_flags + ["-fno-short-enums"],
+        + [
+            "-fno-short-enums",
+        ]
+        + weak_symbols_flags,
+        cxxflags=extra_toolchain_flags
+        + [
+            "-fno-short-enums",
+        ]
+        + weak_symbols_flags,
         ldflags=extra_toolchain_flags,
-        asflags=extra_toolchain_flags + ["-DANDROID"],
+        asflags=extra_toolchain_flags
+        + [
+            "-DANDROID",
+        ]
+        + wead_symbols_defines,
     )
 
 

media/libcubeb/src/moz.build

@@ -95,7 +95,7 @@ if CONFIG['MOZ_AAUDIO'] or CONFIG['MOZ_OPENSL']:
 
 if CONFIG['MOZ_AAUDIO']:
     SOURCES += ['cubeb_aaudio.cpp']
-    SOURCES['cubeb_aaudio.cpp'].flags += ['-D__ANDROID_UNAVAILABLE_SYMBOLS_ARE_WEAK__']
+    SOURCES['cubeb_aaudio.cpp'].flags += ['-Wno-unguarded-availability']
     DEFINES['USE_AAUDIO'] = True
 
 if CONFIG['MOZ_OPENSL']:

memory/replace/logalloc/replay/moz.build

@@ -29,6 +29,11 @@ if CONFIG["OS_TARGET"] == "Darwin":
     # when building with MACOSX_DEPLOYMENT_TARGET < 10.15 with >= 10.15 SDK.
     # We have our own definition of the function, so it doesn't matter what the SDK says.
     SOURCES["Replay.cpp"].flags += ["-Wno-unguarded-availability-new"]
+elif CONFIG["OS_TARGET"] == "Android":
+    # Work around "warning: 'aligned_alloc' is only available on Android 27 or
+    # lower. We have our own definition of the function, so it doesn't matter.
+    SOURCES["Replay.cpp"].flags += ["-Wno-unguarded-availability"]
+
 
 if CONFIG["MOZ_REPLACE_MALLOC_STATIC"] and (CONFIG["MOZ_DMD"] or CONFIG["MOZ_PHC"]):
     UNIFIED_SOURCES += [