Bazel build implementation, doesn't provide options for the compilation modes opt and debug (#2395)

* Bazel add default compliation args for opt and debug. Can be overriden

* Add docstrings for new compilation mode override flags

* Remove cc_args_list shims, which arent needed anymore for cc_feature

* Add Compilation mode overrides to the BAZEL_ONLY_ALLOWLIST, these dont exist in Cmake

* For completness add the fastbuild default options, and override flag

* Remove the default options for fastbuiild, as the bazel doc defaults didnt make much sense, nor work. Leaving these for completness and future addition

* Rename the config and constraint labels from OVERRIDE to REMOVE_DEFS

* Change naming of flags from PICO_COMPILATION_XXX_REMOVE_DEFS to PICO_COMPILATION_NO_XXX_ARGS for OPT, FASTBUILD & DEBUG variants

* Fixup spellling mistakes, and comments

* Fix typo PICO_COMPILATION_NO_FASBUILD_ARGS to FASTBUILD

bazel/config/BUILD.bazel

@@ -300,3 +300,21 @@ label_flag(
     name = "PICO_MBEDTLS_CONFIG",
     build_setting_default = "//bazel:empty_cc_lib",
 )
+
+# PICO_BAZEL_CONFIG: PICO_COMPILATION_NO_OPT_ARGS, Makes the opt compilation mode a no-op so custom optimization arguments can be injected via the --copt flag instead, type=bool, default=0, group=build
+bool_flag(
+    name = "PICO_COMPILATION_NO_OPT_ARGS",
+    build_setting_default = False,
+)
+
+# PICO_BAZEL_CONFIG: PICO_COMPILATION_NO_DEBUG_ARGS, Makes the debug compilation mode a no-op so custom debug arguments can be injected via the --copt flag instead, type=bool, default=0, group=build
+bool_flag(
+    name = "PICO_COMPILATION_NO_DEBUG_ARGS",
+    build_setting_default = False,
+)
+
+# PICO_BAZEL_CONFIG: PICO_COMPILATION_NO_FASTBUILD_ARGS, Makes the fastbuild compilation mode a no-op so custom fastbuild arguments can be injected via the --copt flag instead, type=bool, default=0, group=build
+bool_flag(
+    name = "PICO_COMPILATION_NO_FASTBUILD_ARGS",
+    build_setting_default = False,
+)

bazel/constraint/BUILD.bazel

@@ -258,3 +258,18 @@ label_flag_matches(
     flag = "//bazel/config:PICO_MBEDTLS_CONFIG",
     value = "//bazel:empty_cc_lib",
 )
+
+config_setting(
+    name = "pico_compilation_no_opt_args_set",
+    flag_values = {"//bazel/config:PICO_COMPILATION_NO_OPT_ARGS": "True"},
+)
+
+config_setting(
+    name = "pico_compilation_no_debug_args_set",
+    flag_values = {"//bazel/config:PICO_COMPILATION_NO_DEBUG_ARGS": "True"},
+)
+
+config_setting(
+    name = "pico_compilation_no_fastbuild_args_set",
+    flag_values = {"//bazel/config:PICO_COMPILATION_NO_FASTBUILD_ARGS": "True"},
+)

bazel/toolchain/BUILD.bazel

@@ -89,15 +89,46 @@ cc_args(
 )
 
 cc_args(
-    name = "opt_debug_args",
+    name = "debug_args",
     actions = [
         "@rules_cc//cc/toolchains/actions:compile_actions",
         "@rules_cc//cc/toolchains/actions:link_actions",
     ],
-    args = [
+    args = select({
-        "-Og",  # TODO: Make this configurable.
+        "//bazel/constraint:pico_compilation_no_debug_args_set": [],
+        "//conditions:default": [
+            "-Og",
             "-g3",
         ],
+    })
+)
+
+cc_args(
+    name = "opt_args",
+    actions = [
+        "@rules_cc//cc/toolchains/actions:compile_actions",
+        "@rules_cc//cc/toolchains/actions:link_actions",
+    ],
+    args = select({
+        "//bazel/constraint:pico_compilation_no_opt_args_set": [],
+        "//conditions:default": [
+            "-O2",
+            "-DNDEBUG",
+        ],
+    })
+)
+
+cc_args(
+    name = "fastbuild_args",
+    actions = [
+        "@rules_cc//cc/toolchains/actions:compile_actions",
+        "@rules_cc//cc/toolchains/actions:link_actions",
+    ],
+    args = select({
+        "//bazel/constraint:pico_compilation_no_fastbuild_args_set": [],
+        # The conditions default are kept as nothing here, The bazel docs default are -gmlt -Wl,-S.
+        "//conditions:default": [],
+    })
 )
 
 configurable_toolchain_feature(
@@ -132,16 +163,23 @@ configurable_toolchain_feature(
     linkopts = ["-Wl,-z,max-page-size=4096"],
 )
 
-# TODO: Make this shim unnecessary.
+
-cc_args_list(
+cc_feature(
-    name = "all_opt_debug_args",
+    name = "dbg",
-    args = [":opt_debug_args"],
+    args = [":debug_args"],
+    overrides = "@rules_cc//cc/toolchains/features:dbg",
 )
 
 cc_feature(
-    name = "override_debug",
+    name = "opt",
-    args = [":all_opt_debug_args"],
+    args = [":opt_args"],
-    overrides = "@rules_cc//cc/toolchains/features:dbg",
+    overrides = "@rules_cc//cc/toolchains/features:opt",
+)
+
+cc_feature(
+    name = "fastbuild",
+    args = [":fastbuild_args"],
+    overrides = "@rules_cc//cc/toolchains/features:fastbuild",
 )
 
 HOSTS = (
@@ -180,7 +218,9 @@ _HOST_CPU_CONSTRAINTS = {
     tags = ["manual"],  # Don't try to build this in wildcard builds.
     known_features = [
         "@rules_cc//cc/toolchains/args:experimental_replace_legacy_action_config_features",
-        "@pico-sdk//bazel/toolchain:override_debug",
+        "@pico-sdk//bazel/toolchain:dbg",
+        "@pico-sdk//bazel/toolchain:opt",
+        "@pico-sdk//bazel/toolchain:fastbuild",
         "@pico-sdk//bazel/toolchain:gc_sections",
         "@pico-sdk//bazel/toolchain:cxx_no_exceptions",
         "@pico-sdk//bazel/toolchain:cxx_no_rtti",
@@ -189,7 +229,6 @@ _HOST_CPU_CONSTRAINTS = {
     ],
     enabled_features = [
         "@rules_cc//cc/toolchains/args:experimental_replace_legacy_action_config_features",
-        "@pico-sdk//bazel/toolchain:override_debug",
     ] + select({
         "//bazel/constraint:pico_no_gc_sections_enabled": [],
         "//conditions:default": [":gc_sections"],
@@ -232,7 +271,9 @@ _HOST_CPU_CONSTRAINTS = {
     tags = ["manual"],  # Don't try to build this in wildcard builds.
     known_features = [
         "@rules_cc//cc/toolchains/args:experimental_replace_legacy_action_config_features",
-        "@pico-sdk//bazel/toolchain:override_debug",
+        "@pico-sdk//bazel/toolchain:dbg",
+        "@pico-sdk//bazel/toolchain:opt",
+        "@pico-sdk//bazel/toolchain:fastbuild",
         "@pico-sdk//bazel/toolchain:gc_sections",
         "@pico-sdk//bazel/toolchain:cxx_no_exceptions",
         "@pico-sdk//bazel/toolchain:cxx_no_rtti",
@@ -241,7 +282,6 @@ _HOST_CPU_CONSTRAINTS = {
     ],
     enabled_features = [
         "@rules_cc//cc/toolchains/args:experimental_replace_legacy_action_config_features",
-        "@pico-sdk//bazel/toolchain:override_debug",
     ] + select({
         "//bazel/constraint:pico_no_gc_sections_enabled": [],
         "//conditions:default": [":gc_sections"],

tools/compare_build_systems.py

@@ -158,6 +158,10 @@ BAZEL_ONLY_ALLOWLIST = (
     "PICO_BT_ENABLE_BLE",
     "PICO_BT_ENABLE_CLASSIC",
     "PICO_BT_ENABLE_MESH",
+    # Compilation modes remove, These allow the user to remove the defaults, with no args. See --compilation_mode cmd line option
+    "PICO_COMPILATION_NO_OPT_ARGS",
+    "PICO_COMPILATION_NO_DEBUG_ARGS",
+    "PICO_COMPILATION_NO_FASTBUILD_ARGS",
 )