[BoundsSafety] Add build settings to control the bounds check mode for -fbounds-safety

This patch introduces two new build settings

The first is `CLANG_BOUNDS_SAFETY_BRINGUP_MISSING_CHECKS`. This setting can be used
to control which new bounds checks are enabled. It takes two special
values:

1. `none` - This disables all the new bounds checks. This corresponds to
   `-fno-bounds-safety-bringup-missing-checks`.
2. `default` - This will use the compiler default (i.e. the build system
   won't pass the `-fbounds-safety-bringup-missing-checks=` flag).

If the build setting value is not any of the special values it is passed
directly as an argument to `-fbounds-safety-bringup-missing-checks=`.
This allows enabling a specific set of checks. E.g.:

```
CLANG_BOUNDS_SAFETY_BRINGUP_MISSING_CHECKS=access_size,return_size
```

would pass `-fbounds-safety-bringup-missing-checks=access_size,return-size`.

The second build setting is
`CLANG_BOUNDS_SAFETY_BRINGUP_MISSING_CHECKS_OPT_OUTS`. This setting is
intended to complement the previous build setting by providing a way to
opt out of specific bounds checks. E.g.:

```
CLANG_BOUNDS_SAFETY_BRINGUP_MISSING_CHECKS=batch_0
CLANG_BOUNDS_SAFETY_BRINGUP_MISSING_CHECKS_OPT_OUTS=access_size
```

This is equivalent to

```
-fbound-safety-bringup-missing-checks=batch_0 -fno-bounds-safety-bringup-missing-checks=access_size
```

This opts the compilation unit into all checks in the `batch_0` group
except the `access_size` bounds check.

These new build settings only apply when all of the following are true:

* `CLANG_ENABLE_BOUNDS_SAFETY` or `CLANG_ENABLE_BOUNDS_ATTRIBUTES` is enabled.
* For C source files

The existing `boundsSafetyCLanguageExtension` test case has been
modified to test the behavior of these new flags.

rdar://161599307

Author: danliew-apple

Sources/SWBUniversalPlatform/Specs/Clang.xcspec

@@ -543,6 +543,44 @@
                 };
                 // Hidden.
             },
+            {
+                Name = "CLANG_BOUNDS_SAFETY_BRINGUP_MISSING_CHECKS";
+                Type = Enumeration;
+                FileTypes = (
+                    "sourcecode.c.c",
+                );
+                Values = (
+                    "none",
+                    "default",
+                );
+                DefaultValue = "default";
+                CommandLineArgs = {
+                    "none" = ( "-fno-bounds-safety-bringup-missing-checks" );
+                    // Use the compiler default
+                    "default" = ();
+                    // E.g. `batch_0` or `all` or comma separated lists of checks to enable
+                    "<<otherwise>>" = ( "-fbounds-safety-bringup-missing-checks=$(value)" );
+                };
+
+                Condition = "$(CLANG_ENABLE_BOUNDS_ATTRIBUTES) || $(CLANG_ENABLE_BOUNDS_SAFETY)";
+                // Hidden
+            },
+            {
+              Name = "CLANG_BOUNDS_SAFETY_BRINGUP_MISSING_CHECKS_OPT_OUTS";
+              Type = String;
+              FileTypes = (
+                    "sourcecode.c.c",
+                );
+              DefaultValue = "";
+              CommandLineArgs = {
+                "" = ();
+                // Comma separated list of checks to disable
+                "<<otherwise>>" = ( "-fno-bounds-safety-bringup-missing-checks=$(value)" );
+              };
+              Condition = "$(CLANG_ENABLE_BOUNDS_ATTRIBUTES) || $(CLANG_ENABLE_BOUNDS_SAFETY)";
+              AppearsAfter = "CLANG_BOUNDS_SAFETY_BRINGUP_MISSING_CHECKS";
+              // Hidden
+            },
             {
                 Name = "CLANG_ENABLE_APP_EXTENSION";
                 Type = Boolean;

Tests/SWBTaskConstructionTests/TaskConstructionTests.swift

@@ -9185,6 +9185,72 @@ fileprivate struct TaskConstructionTests: CoreBasedTests {
                     }
                 }
             }
+
+            // Test missing check build settings
+            let boundsSafetyMissingChecksSetting = "CLANG_BOUNDS_SAFETY_BRINGUP_MISSING_CHECKS"
+            let enableBoundsAttributesSetting = "CLANG_ENABLE_BOUNDS_ATTRIBUTES"
+            let boundsSafetyMissingChecksOptOutsSetting = "CLANG_BOUNDS_SAFETY_BRINGUP_MISSING_CHECKS_OPT_OUTS"
+
+            for (enableBoundsSafetyBuildSetting, enableBoundsSafetyFlag) in [
+                (enableBoundsSafetySetting,"-fbounds-safety"),
+                (enableBoundsAttributesSetting, "-fbounds-attributes")] {
+
+                // Maps an array of build overrides to a closure that tests properties of the build overrides
+                let missingChecksOverrides = [
+                    [ enableBoundsSafetyBuildSetting: "YES", boundsSafetyMissingChecksSetting: "none"]: { (task: any PlannedTask) in
+                        task.checkCommandLineContains(["-fno-bounds-safety-bringup-missing-checks"])
+                    },
+
+                    // Default behavior is not pass the compiler flag and thus use the compiler default
+                    [ enableBoundsSafetyBuildSetting: "YES", boundsSafetyMissingChecksSetting: "default"]: { (task: any PlannedTask) in
+                        task.checkCommandLineDoesNotContain("-fno-bounds-safety-bringup-missing-checks")
+                        task.checkCommandLineDoesNotContain("-fbounds-safety-bringup-missing-checks")
+                    },
+                    [ enableBoundsSafetyBuildSetting: "YES"]: { (task: any PlannedTask) in
+                        task.checkCommandLineDoesNotContain("-fno-bounds-safety-bringup-missing-checks")
+                        task.checkCommandLineDoesNotContain("-fbounds-safety-bringup-missing-checks")
+                    },
+
+
+                    [ enableBoundsSafetyBuildSetting: "YES", boundsSafetyMissingChecksSetting: "batch_0"]: { (task: any PlannedTask) in
+                        task.checkCommandLineContains(["-fbounds-safety-bringup-missing-checks=batch_0"])
+                        task.checkCommandLineDoesNotContain("-fno-bounds-safety-bringup-missing-checks")
+                    },
+                    [ enableBoundsSafetyBuildSetting: "YES", boundsSafetyMissingChecksSetting: "access_size,return_size"]: { (task: any PlannedTask) in
+                        task.checkCommandLineContains(["-fbounds-safety-bringup-missing-checks=access_size,return_size"])
+                        task.checkCommandLineDoesNotContain("-fno-bounds-safety-bringup-missing-checks")
+                    },
+
+                    // Opt-outs
+                    [ enableBoundsSafetyBuildSetting: "YES",
+                      boundsSafetyMissingChecksSetting: "batch_0",
+                      boundsSafetyMissingChecksOptOutsSetting: "access_size"]: { (task: any PlannedTask) in
+                        task.checkCommandLineContains([
+                            "-fbounds-safety-bringup-missing-checks=batch_0",
+                            "-fno-bounds-safety-bringup-missing-checks=access_size"])
+                    },
+                    [ enableBoundsSafetyBuildSetting: "YES",
+                      boundsSafetyMissingChecksSetting: "batch_0",
+                      boundsSafetyMissingChecksOptOutsSetting: "access_size,return_size"]: { (task: any PlannedTask) in
+                        task.checkCommandLineContains([
+                            "-fbounds-safety-bringup-missing-checks=batch_0",
+                            "-fno-bounds-safety-bringup-missing-checks=access_size,return_size"])
+                    },
+                ]
+
+                for (overrides, checkOverrideProperties) in missingChecksOverrides {
+                    await tester.checkBuild(BuildParameters(configuration: "Debug", overrides: overrides), runDestination: .macOS, fs: fs) { results -> Void in
+                        results.checkTarget("AppTarget") { target -> Void in
+                            results.checkTask(.matchTarget(target), .matchRuleType("CompileC"), body: {task in
+                                // Check the overrides contains -fbounds-safety or -fbounds-attributes
+                                task.checkCommandLineContains([enableBoundsSafetyFlag])
+                                // Check properties specific to this array of overrides
+                                checkOverrideProperties(task)
+                            })
+                        }
+                    }
+                }
+            }
         }
     }