Add clang-tidy support

For every file which we can run clang-tidy (C/C++ clang-built), we add a
new build node that depends on the object file (since clang-tidy does
not export a depfile), and is depended on by the link step. This is
better than how we're doing it in make, since calling tidy can be turned
on or off without needing to rebuild the object files.

This does not attempt to port WITH_TIDY_ONLY from Make, since the way
that it works is broken (due to the lack of a depfile).

Bug: 32244182
Test: WITH_TIDY=true mmma -j bionic/libc
Test: ./soong (Setting ClangTidy: true)
Change-Id: I40bbb5bb00d292d72bf1c293b93080b5f9f6d8ea

cc/check.go

@@ -105,3 +105,31 @@ func CheckBadHostLdlibs(ctx ModuleContext, prop string, flags []string) {
 		}
 	}
 }
+
+// Check for bad clang tidy flags
+func CheckBadTidyFlags(ctx ModuleContext, prop string, flags []string) {
+	for _, flag := range flags {
+		flag = strings.TrimSpace(flag)
+
+		if !strings.HasPrefix(flag, "-") {
+			ctx.PropertyErrorf(prop, "Flag `%s` must start with `-`", flag)
+		} else if strings.HasPrefix(flag, "-fix") {
+			ctx.PropertyErrorf(prop, "Flag `%s` is not allowed, since it could cause multiple writes to the same source file", flag)
+		} else if strings.HasPrefix(flag, "-checks=") {
+			ctx.PropertyErrorf(prop, "Flag `%s` is not allowed, use `tidy_checks` property instead", flag)
+		} else if strings.Contains(flag, " ") {
+			ctx.PropertyErrorf(prop, "Bad flag: `%s` is not an allowed multi-word flag. Should it be split into multiple flags?", flag)
+		}
+	}
+}
+
+// Check for bad clang tidy checks
+func CheckBadTidyChecks(ctx ModuleContext, prop string, checks []string) {
+	for _, check := range checks {
+		if strings.Contains(check, " ") {
+			ctx.PropertyErrorf("tidy_checks", "Check `%s` invalid, cannot contain spaces", check)
+		} else if strings.Contains(check, ",") {
+			ctx.PropertyErrorf("tidy_checks", "Check `%s` invalid, cannot contain commas. Split each entry into it's own string instead", check)
+		}
+	}
+}