[SCons] Split `targets.py`, apply flags from tools

Split `targets` tool logic, moving all the compiler-specific flags to a
new `common_compiler_flags.py` file, and everything else (CPPDEFINES,
optimize option logic, dev build logic, etc) to the `godotcpp` tool.

The default tools now apply the common compiler flags by importing the
file and explicitly calling `configure`.

1 files changed, 94 insertions, 0 deletions

diff --git a/tools/common_compiler_flags.py b/tools/common_compiler_flags.py
new file mode 100644
index 0000000..838dbcf
--- /dev/null
+++ b/tools/common_compiler_flags.py
@@ -0,0 +1,94 @@
+import os
+import subprocess
+import sys
+
+
+def using_clang(env):
+    return "clang" in os.path.basename(env["CC"])
+
+
+def is_vanilla_clang(env):
+    if not using_clang(env):
+        return False
+    try:
+        version = subprocess.check_output([env.subst(env["CXX"]), "--version"]).strip().decode("utf-8")
+    except (subprocess.CalledProcessError, OSError):
+        print("Couldn't parse CXX environment variable to infer compiler version.")
+        return False
+    return not version.startswith("Apple")
+
+
+def exists(env):
+    return True
+
+
+def generate(env):
+    # Require C++17
+    if env.get("is_msvc", False):
+        env.Append(CXXFLAGS=["/std:c++17"])
+    else:
+        env.Append(CXXFLAGS=["-std=c++17"])
+
+    # Disable exception handling. Godot doesn't use exceptions anywhere, and this
+    # saves around 20% of binary size and very significant build time.
+    if env["disable_exceptions"]:
+        if env.get("is_msvc", False):
+            env.Append(CPPDEFINES=[("_HAS_EXCEPTIONS", 0)])
+        else:
+            env.Append(CXXFLAGS=["-fno-exceptions"])
+    elif env.get("is_msvc", False):
+        env.Append(CXXFLAGS=["/EHsc"])
+
+    if not env.get("is_msvc", False):
+        if env["symbols_visibility"] == "visible":
+            env.Append(CCFLAGS=["-fvisibility=default"])
+            env.Append(LINKFLAGS=["-fvisibility=default"])
+        elif env["symbols_visibility"] == "hidden":
+            env.Append(CCFLAGS=["-fvisibility=hidden"])
+            env.Append(LINKFLAGS=["-fvisibility=hidden"])
+
+    # Set optimize and debug_symbols flags.
+    # "custom" means do nothing and let users set their own optimization flags.
+    if env.get("is_msvc", False):
+        if env["debug_symbols"]:
+            env.Append(CCFLAGS=["/Zi", "/FS"])
+            env.Append(LINKFLAGS=["/DEBUG:FULL"])
+
+        if env["optimize"] == "speed":
+            env.Append(CCFLAGS=["/O2"])
+            env.Append(LINKFLAGS=["/OPT:REF"])
+        elif env["optimize"] == "speed_trace":
+            env.Append(CCFLAGS=["/O2"])
+            env.Append(LINKFLAGS=["/OPT:REF", "/OPT:NOICF"])
+        elif env["optimize"] == "size":
+            env.Append(CCFLAGS=["/O1"])
+            env.Append(LINKFLAGS=["/OPT:REF"])
+        elif env["optimize"] == "debug" or env["optimize"] == "none":
+            env.Append(CCFLAGS=["/Od"])
+    else:
+        if env["debug_symbols"]:
+            # Adding dwarf-4 explicitly makes stacktraces work with clang builds,
+            # otherwise addr2line doesn't understand them.
+            env.Append(CCFLAGS=["-gdwarf-4"])
+            if env.dev_build:
+                env.Append(CCFLAGS=["-g3"])
+            else:
+                env.Append(CCFLAGS=["-g2"])
+        else:
+            if using_clang(env) and not is_vanilla_clang(env):
+                # Apple Clang, its linker doesn't like -s.
+                env.Append(LINKFLAGS=["-Wl,-S", "-Wl,-x", "-Wl,-dead_strip"])
+            else:
+                env.Append(LINKFLAGS=["-s"])
+
+        if env["optimize"] == "speed":
+            env.Append(CCFLAGS=["-O3"])
+        # `-O2` is friendlier to debuggers than `-O3`, leading to better crash backtraces.
+        elif env["optimize"] == "speed_trace":
+            env.Append(CCFLAGS=["-O2"])
+        elif env["optimize"] == "size":
+            env.Append(CCFLAGS=["-Os"])
+        elif env["optimize"] == "debug":
+            env.Append(CCFLAGS=["-Og"])
+        elif env["optimize"] == "none":
+            env.Append(CCFLAGS=["-O0"])