Bug 1883940 - Replace MOZ_CXX11 autoconf macro by a moz.configure check r=glandium

Differential Revision: https://phabricator.services.mozilla.com/D203781

build/autoconf/toolchain.m4

@@ -81,37 +81,3 @@ AC_PROG_CXX
 
 PATH=$_SAVE_PATH
 ])
-
-AC_DEFUN([MOZ_CXX11],
-[
-dnl Updates to the test below should be duplicated further below for the
-dnl cross-compiling case.
-AC_LANG_CPLUSPLUS
-if test "$GNU_CXX"; then
-    AC_CACHE_CHECK([whether 64-bits std::atomic requires -latomic],
-        ac_cv_needs_atomic,
-        AC_TRY_LINK(
-            [#include <cstdint>
-             #include <atomic>],
-            [ std::atomic<uint64_t> foo; foo = 1; ],
-            ac_cv_needs_atomic=no,
-            _SAVE_LIBS="$LIBS"
-            LIBS="$LIBS -latomic"
-            AC_TRY_LINK(
-                [#include <cstdint>
-                 #include <atomic>],
-                [ std::atomic<uint64_t> foo; foo = 1; ],
-                ac_cv_needs_atomic=yes,
-                ac_cv_needs_atomic="do not know; assuming no")
-            LIBS="$_SAVE_LIBS"
-        )
-    )
-    if test "$ac_cv_needs_atomic" = yes; then
-      MOZ_NEEDS_LIBATOMIC=1
-    else
-      MOZ_NEEDS_LIBATOMIC=
-    fi
-    AC_SUBST(MOZ_NEEDS_LIBATOMIC)
-fi
-AC_LANG_C
-])

build/moz.configure/libraries.configure

@@ -114,3 +114,35 @@ with only_when(moz_use_pthreads):
         compilation_flags.cxxflags.extend(pthread_flags.cflags)
 
     set_config("MOZ_USE_PTHREADS", True)
+
+
+with only_when(building_with_gnu_cc):
+
+    @template
+    def check_std_atomic_requirements(flag=None, when=None):
+        return try_link(
+            includes=["cstdint", "atomic"],
+            body="std::atomic<uint64_t> foo; foo = 1;",
+            flags=flag or [],
+            when=when,
+        )
+
+    is_libatomic_optional = check_std_atomic_requirements()
+    is_libatomic_required = check_std_atomic_requirements(
+        flag="-latomic", when=~is_libatomic_optional
+    )
+
+    @depends(is_libatomic_optional, is_libatomic_required)
+    @checking("whether 64-bits std::atomic requires -latomic")
+    def checking_needs_libatomic(is_libatomic_optional, is_libatomic_required):
+        if is_libatomic_optional:
+            return False
+        if is_libatomic_required:
+            return True
+        return "do not know; assuming no"
+
+    set_config(
+        "LIBATOMIC_LIBS",
+        ["-latomic"],
+        when=depends(checking_needs_libatomic)(lambda c: c is True),
+    )

js/src/build/moz.build

@@ -90,8 +90,7 @@ if CONFIG["OS_ARCH"] == "WINNT":
             "synchronization",
         ]
 
-if CONFIG["MOZ_NEEDS_LIBATOMIC"]:
+OS_LIBS += CONFIG["LIBATOMIC_LIBS"]
-    OS_LIBS += ["atomic"]
 
 if CONFIG["TARGET_OS"] == "iOS":
     OS_LIBS += ["-framework BrowserEngineCore"]

js/src/old-configure.in

@@ -429,13 +429,6 @@ if test -n "$COMPILE_ENVIRONMENT"; then
 fi
 
 if test -z "$SKIP_COMPILER_CHECKS"; then
-dnl Checks for typedefs, structures, and compiler characteristics.
-dnl ========================================================
-
-AC_LANG_CPLUSPLUS
-
-MOZ_CXX11
-
 
 dnl ========================================================
 dnl Put your C++ language/feature checks below

media/ffvpx/libavutil/moz.build

@@ -90,7 +90,6 @@ OS_LIBS += CONFIG['REALTIME_LIBS']
 if CONFIG['OS_TARGET'] != 'WINNT':
     OS_LIBS += ['m']
 
-if CONFIG['MOZ_NEEDS_LIBATOMIC']:
+OS_LIBS += CONFIG["LIBATOMIC_LIBS"]
-    OS_LIBS += ['atomic']
 
 include("../ffvpxcommon.mozbuild")

memory/mozjemalloc_info/moz.build

@@ -21,8 +21,7 @@ USE_LIBS += [
 # The memory library defines this, so it's needed here too.
 DEFINES["IMPL_MFBT"] = True
 
-if CONFIG["MOZ_NEEDS_LIBATOMIC"]:
+OS_LIBS += CONFIG["LIBATOMIC_LIBS"]
-    OS_LIBS += ["atomic"]
 
 UNIFIED_SOURCES += [
     "/mfbt/double-conversion/double-conversion/bignum-dtoa.cc",

memory/replace/logalloc/replay/moz.build

@@ -79,8 +79,7 @@ USE_LIBS += [
 # The memory library defines this, so it's needed here too.
 DEFINES["IMPL_MFBT"] = True
 
-if CONFIG["MOZ_NEEDS_LIBATOMIC"]:
+OS_LIBS += CONFIG["LIBATOMIC_LIBS"]
-    OS_LIBS += ["atomic"]
 
 OS_LIBS += CONFIG["DL_LIBS"]
 

mfbt/moz.build

@@ -205,8 +205,7 @@ SOURCES["lz4/xxhash.c"].flags += ["-Wno-unused-function"]
 
 DisableStlWrapping()
 
-if CONFIG["MOZ_NEEDS_LIBATOMIC"]:
+OS_LIBS += CONFIG["LIBATOMIC_LIBS"]
-    OS_LIBS += ["atomic"]
 
 DEFINES["LZ4LIB_VISIBILITY"] = ""
 

old-configure.in

@@ -446,14 +446,6 @@ else
 fi # COMPILE_ENVIRONMENT
 
 if test -z "$SKIP_COMPILER_CHECKS"; then
-dnl Checks for typedefs, structures, and compiler characteristics.
-dnl ========================================================
-AC_LANG_CPLUSPLUS
-
-MOZ_CXX11
-
-AC_LANG_C
-
 
 dnl ========================================================
 dnl Put your C++ language/feature checks below

toolkit/library/moz.build

@@ -86,8 +86,7 @@ def Libxul(name, output_category=None):
 
     Libxul_defines()
 
-    if CONFIG["MOZ_NEEDS_LIBATOMIC"]:
+    OS_LIBS += CONFIG["LIBATOMIC_LIBS"]
-        OS_LIBS += ["atomic"]
 
     # TouchBar-related classes are only available in the 10.12.2 SDK and later.
     # We need to weak link these classes until we've upgraded our SDK to at