Issue #2262 - Build with C++14 by default

Including infrastructure changes to ensure correct opts for future changes.

Based-on: m-c 1325632, 1418047, 1418573

4 files changed, 154 insertions, 60 deletions

diff --git a/build/moz.configure/compile-checks.configure b/build/moz.configure/compile-checks.configure
index 9ef9496db5..7f45b2d4b1 100644
--- a/build/moz.configure/compile-checks.configure
+++ b/build/moz.configure/compile-checks.configure
@@ -74,55 +74,45 @@ def check_headers(*headers, **kwargs):
     return checks
 
 
-@depends(c_compiler)
-def warnings_cflags(c_compiler):
-    return []
-
-@depends(cxx_compiler)
-def warnings_cxxflags(cxx_compiler):
-    return []
-
-
-# Tests whether GCC or clang support the given warning flag, and if it is,
-# add it to the list of warning flags for the build.
-# - `warning` is the warning flag (e.g. -Wfoo)
+# Determine whether to add a given flag to the given lists of flags for C or
+# C++ compilation.
+# - `flag` is the flag to test
+# - `cflags` is a @depends function for the list of C compiler flags to add to
+# - `cxxflags` is a @depends function for the list of C++ compiler flags to
+#   add to
+# - `test_flags` is a list of flags to pass to the compiler instead of merely
+#   passing `flag`. This is especially useful for checking warning flags. If
+#   this list is empty, `flag` will be passed on its own.
 # - `compiler` (optional) is the compiler to test against (c_compiler or
 #   cxx_compiler, from toolchain.configure). When omitted, both compilers
-#   are tested.
+#   are tested; the list of flags added to is dependent on the compiler tested.
 # - `when` (optional) is a @depends function or option name conditioning
 #   when the warning flag is wanted.
 # - `check`, when not set, skips checking whether the flag is supported and
-#   adds it to the list of warning flags unconditionally. This is only meant
-#   for add_gcc_warning().
+#   adds it to the list of flags unconditionally.
 @template
-def check_and_add_gcc_warning(warning, compiler=None, when=None, check=True):
-    if compiler:
+def check_and_add_flags(flag, cflags, cxxflags, test_flags,
+                        compiler=None, when=None, check=True):
+    if compiler is not None:
         compilers = (compiler,)
     else:
         compilers = (c_compiler, cxx_compiler)
 
-    when = when or always
+    if when is None:
+        when = always
+
+    if test_flags:
+        flags = test_flags
+    else:
+        flags = [flag]
 
     for c in compilers:
         assert c in (c_compiler, cxx_compiler)
-        lang, warnings_flags = {
-            c_compiler: ('C', warnings_cflags),
-            cxx_compiler: ('C++', warnings_cxxflags),
+        lang, list_of_flags = {
+            c_compiler: ('C', cflags),
+            cxx_compiler: ('C++', cxxflags),
         }[c]
 
-        # GCC and clang will fail if given an unknown warning option like
-        # -Wfoobar. But later versions won't fail if given an unknown negated
-        # warning option like -Wno-foobar. So when we are checking for support
-        # of a negated warning option, we actually test the positive form, but
-        # add the negated form to the flags variable.
-        if (warning.startswith('-Wno-') and
-                not warning.startswith('-Wno-error=')):
-            flags = ['-Werror', '-W' + warning[5:]]
-        elif warning.startswith('-Werror='):
-            flags = [warning]
-        else:
-            flags = ['-Werror', warning]
-
         @depends(c, when)
         def result(c, when):
             if when and c.type in ('clang', 'gcc'):
@@ -131,13 +121,51 @@ def check_and_add_gcc_warning(warning, compiler=None, when=None, check=True):
         if check:
             result = c.try_compile(
                 flags=flags, when=result,
-                check_msg='whether the %s compiler supports %s' % (lang,
-                                                                   warning))
+                check_msg='whether the %s compiler supports %s' % (lang, flag))
 
-        @depends(result, warnings_flags)
-        def maybe_add_flag(result, warnings_flags):
+        @depends(result, list_of_flags)
+        def maybe_add_flag(result, list_of_flags):
             if result:
-                warnings_flags.append(warning)
+                list_of_flags.append(flag)
+
+
+@depends(c_compiler)
+def warnings_cflags(c_compiler):
+    return []
+
+@depends(cxx_compiler)
+def warnings_cxxflags(cxx_compiler):
+    return []
+
+
+# Tests whether GCC or clang support the given warning flag, and if it is,
+# add it to the list of warning flags for the build.
+# - `warning` is the warning flag (e.g. -Wfoo)
+# - `compiler` (optional) is the compiler to test against (c_compiler or
+#   cxx_compiler, from toolchain.configure). When omitted, both compilers
+#   are tested.
+# - `when` (optional) is a @depends function or option name conditioning
+#   when the warning flag is wanted.
+# - `check`, when not set, skips checking whether the flag is supported and
+#   adds it to the list of warning flags unconditionally. This is only meant
+#   for add_gcc_warning().
+@template
+def check_and_add_gcc_warning(warning, compiler=None, when=None, check=True):
+    # GCC and clang will fail if given an unknown warning option like
+    # -Wfoobar. But later versions won't fail if given an unknown negated
+    # warning option like -Wno-foobar. So when we are checking for support
+    # of a negated warning option, we actually test the positive form, but
+    # add the negated form to the flags variable.
+    if warning.startswith('-Wno-') and not warning.startswith('-Wno-error='):
+        flags = ['-Werror', '-W' + warning[5:]]
+    elif warning.startswith('-Werror='):
+        flags = [warning]
+    else:
+        flags = ['-Werror', warning]
+
+    check_and_add_flags(warning, warnings_cflags, warnings_cxxflags,
+                        flags, compiler=compiler, when=when, check=check)
+
 
 # Add the given warning to the list of warning flags for the build.
 # - `warning` is the warning flag (e.g. -Wfoo)
@@ -149,3 +177,45 @@ def check_and_add_gcc_warning(warning, compiler=None, when=None, check=True):
 @template
 def add_gcc_warning(warning, compiler=None, when=None):
     check_and_add_gcc_warning(warning, compiler, when, check=False)
+
+
+# Like the warning checks above, but for general compilation flags.
+@dependable
+def compilation_cflags():
+    return []
+
+
+@dependable
+def compilation_cxxflags():
+    return []
+
+
+# Tests whether GCC or clang support the given compilation flag; if the flag
+# is supported, add it to the list of compilation flags for the build.
+# - `flag` is the flag to test
+# - `compiler` (optional) is the compiler to test against (c_compiler or
+#   cxx_compiler, from toolchain.configure). When omitted, both compilers
+#   are tested.
+# - `when` (optional) is a @depends function or option name conditioning
+#   when the warning flag is wanted.
+# - `check`, when not set, skips checking whether the flag is supported and
+#   adds it to the list of flags unconditionally. This is only meant for
+#   add_gcc_flag().
+@template
+def check_and_add_gcc_flag(flag, compiler=None, when=None, check=True):
+    flags = ['-Werror', flag]
+
+    check_and_add_flags(flag, compilation_cflags, compilation_cxxflags,
+                        flags, compiler=compiler, when=when, check=check)
+
+
+# Add the given flag to the list of flags for the build.
+# - `flag` is the flag (e.g. -fno-sized-deallocation)
+# - `compiler` (optional) is the compiler to add the flag for (c_compiler or
+#   cxx_compiler, from toolchain.configure). When omitted, the flag is added
+#   for both compilers.
+# - `when` (optional) is a @depends function or option name conditioning
+#   when the flag is wanted.
+@template
+def add_gcc_flag(warning, compiler=None, when=None):
+    check_and_add_gcc_flag(warning, compiler, when, check=False)
diff --git a/build/moz.configure/flags.configure b/build/moz.configure/flags.configure
new file mode 100644
index 0000000000..c98f5088db
--- /dev/null
+++ b/build/moz.configure/flags.configure
@@ -0,0 +1,13 @@
+# -*- Mode: python; c-basic-offset: 4; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# We support C++14, but we don't want to enable the sized deallocation
+# facilities in C++14 yet.
+check_and_add_gcc_flag('-fno-sized-deallocation', compiler=cxx_compiler)
+
+# Please keep these last in this file.
+add_old_configure_assignment('_COMPILATION_CFLAGS', compilation_cflags)
+add_old_configure_assignment('_COMPILATION_CXXFLAGS', compilation_cxxflags)
diff --git a/build/moz.configure/toolchain.configure b/build/moz.configure/toolchain.configure
index 5f03cb2b74..cc0540ea1c 100644
--- a/build/moz.configure/toolchain.configure
+++ b/build/moz.configure/toolchain.configure
@@ -171,6 +171,9 @@ include('compilers-util.configure')
 def try_preprocess(compiler, language, source):
     return try_invoke_compiler(compiler, language, source, ['-E'])
 
+def msvc_std14(): return '-std:c++14'
+def msvc_std17(): return '-std:c++17'
+
 @imports(_from='mozbuild.configure.constants', _import='CompilerType')
 @imports(_from='mozbuild.configure.constants',
          _import='CPU_preprocessor_checks')
@@ -279,6 +282,13 @@ def get_compiler_info(compiler, language):
             'Unknown compiler or compiler not supported.')
 
     cplusplus = int(data.get('cplusplus', '0L').rstrip('L'))
+    if language == 'C++' and type=='msvc' and cplusplus == 199711:
+        # Note: MSVC still reports 199711L for __cplusplus. Fix the report by
+        # assuming it does what we asked it to do.
+        if msvc_std14() in compiler:
+            cplusplus = 201402
+        elif msvc_std17() in compiler:
+            cplusplus = 201703
     stdc_version = int(data.get('STDC_VERSION', '0L').rstrip('L'))
 
     version = data.get('VERSION')
@@ -330,16 +340,17 @@ def check_compiler(compiler, language, target):
         if info.type in ('clang-cl', 'clang', 'gcc'):
             append_flag('-std=gnu99')
 
-    # Note: MSVC, while supporting C++11, still reports 199711L for __cplusplus.
     # Note: this is a strict version check because we used to always add
-    # -std=gnu++11.
+    # -std=gnu++14.
+    cxx14_version = 201402
     if info.language == 'C++':
-        if info.type in ('clang', 'gcc') and info.language_version != 201103:
-            append_flag('-std=gnu++11')
+        if info.type in ('clang', 'gcc') and info.language_version != cxx14_version:
+            append_flag('-std=gnu++14')
         # MSVC 2015 headers include C++14 features, but don't guard them
         # with appropriate checks.
-        if info.type == 'clang-cl' and info.language_version != 201402:
+        if info.type == 'clang-cl' and info.language_version != cxx14_version:
             append_flag('-std=c++14')
+        # MSVC from 2015 on defaults to C++14.
 
     # We force clang-cl to emulate Visual C++ 2015 Update 3 with fallback to
     # cl.exe.
@@ -644,11 +655,17 @@ def compiler(language, host_or_target, c_compiler=None, other_compiler=None,
                               host_or_target)
 
         # Check that the additional flags we got are enough to not require any
-        # more flags.
-        if info.flags:
-            flags += info.flags
-            info = check_compiler(wrapper + [compiler] + flags, language,
-                                  host_or_target)
+        # more flags. If we get an exception, just ignore it; it's liable to be
+        # invalid command-line flags, which means the compiler we're checking
+        # doesn't support those command-line flags and will fail one or more of
+        # the checks below.
+        try:
+            if info.flags:
+                flags += info.flags
+                info = check_compiler(wrapper + [compiler] + flags, language,
+                                      host_or_target)
+        except FatalCheckError:
+            pass
 
         if not info.target_cpu or info.target_cpu != host_or_target.cpu:
             raise FatalCheckError(
@@ -674,10 +691,6 @@ def compiler(language, host_or_target, c_compiler=None, other_compiler=None,
                    info.target_endianness or 'unknown', host_or_target_str,
                    host_or_target.endianness))
 
-        if info.flags:
-            raise FatalCheckError(
-                'Unknown compiler or compiler not supported.')
-
         # Compiler version checks
         # ===================================================
         # Check the compiler version here instead of in `compiler_version` so
@@ -689,7 +702,7 @@ def compiler(language, host_or_target, c_compiler=None, other_compiler=None,
                 % info.version)
 
         # If you want to bump the version check here search for
-        # __cpp_static_assert above, and see the associated comment.
+        # cxx_alignof above, and see the associated comment.
         if info.type == 'clang' and not info.version:
             raise FatalCheckError(
                 'Only clang/llvm 3.6 or newer is supported.')
@@ -704,6 +717,10 @@ def compiler(language, host_or_target, c_compiler=None, other_compiler=None,
                     'See https://developer.mozilla.org/en/'
                     'Windows_Build_Prerequisites' % info.version)
 
+        if info.flags:
+            raise FatalCheckError(
+                'Unknown compiler or compiler not supported.')
+
         return namespace(
             wrapper=wrapper,
             compiler=compiler,
diff --git a/build/moz.configure/warnings.configure b/build/moz.configure/warnings.configure
index b2c3758047..2edf1748ad 100644
--- a/build/moz.configure/warnings.configure
+++ b/build/moz.configure/warnings.configure
@@ -18,9 +18,6 @@ add_old_configure_assignment(
 # lots of useful warnings
 add_gcc_warning('-Wall')
 
-# catches C++ version forward-compat issues
-add_gcc_warning('-Wc++11-compat', cxx_compiler)
-
 # catches bugs, e.g. "if (c); foo();", few false positives
 add_gcc_warning('-Wempty-body')
 
@@ -55,9 +52,6 @@ check_and_add_gcc_warning('-Wclass-varargs')
 check_and_add_gcc_warning('-Wloop-analysis')
 
 # catches C++ version forward-compat issues
-check_and_add_gcc_warning('-Wc++11-compat-pedantic', cxx_compiler)
-check_and_add_gcc_warning('-Wc++14-compat', cxx_compiler)
-check_and_add_gcc_warning('-Wc++14-compat-pedantic', cxx_compiler)
 check_and_add_gcc_warning('-Wc++1z-compat', cxx_compiler)
 
 # catches unintentional switch case fallthroughs