[PATCH v2 4/8] Makefile: Disable readability-math-missing-parentheses clang-tidy check

[Stefano Brivio <sbrivio@redhat.com>]

With clang-tidy and LLVM 19:

/home/sbrivio/passt/conf.c:1218:29: error: '*' has higher precedence than '+'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses,-warnings-as-errors]
 1218 |                 const char *octet = str + 3 * i;
      |                                           ^~~~~~
      |                                           (    )
/home/sbrivio/passt/ndp.c:285:18: error: '*' has higher precedence than '+'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses,-warnings-as-errors]
  285 |                                         .len            = 1 + 2 * n,
      |                                                               ^~~~~~
      |                                                               (    )
/home/sbrivio/passt/ndp.c:329:23: error: '%' has higher precedence than '-'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses,-warnings-as-errors]
  329 |                         memset(ptr, 0, 8 - dns_s_len % 8);      /* padding */
      |                                            ^~~~~~~~~~~~~~
      |                                            (            )
/home/sbrivio/passt/pcap.c:131:20: error: '*' has higher precedence than '+'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses,-warnings-as-errors]
  131 |                 pcap_frame(iov + i * frame_parts, frame_parts, offset, &now);
      |                                  ^~~~~~~~~~~~~~~~
      |                                  (              )
/home/sbrivio/passt/util.c:216:10: error: '/' has higher precedence than '+'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses,-warnings-as-errors]
  216 |                 return (a->tv_nsec + 1000000000 - b->tv_nsec) / 1000 +
      |                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |                        (                                            )
/home/sbrivio/passt/util.c:217:10: error: '*' has higher precedence than '+'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses,-warnings-as-errors]
  217 |                        (a->tv_sec - b->tv_sec - 1) * 1000000;
      |                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |                        (                                    )
/home/sbrivio/passt/util.c:220:9: error: '/' has higher precedence than '+'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses,-warnings-as-errors]
  220 |         return (a->tv_nsec - b->tv_nsec) / 1000 +
      |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |                (                               )
/home/sbrivio/passt/util.c:221:9: error: '*' has higher precedence than '+'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses,-warnings-as-errors]
  221 |                (a->tv_sec - b->tv_sec) * 1000000;
      |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |                (                                )
/home/sbrivio/passt/util.c:545:32: error: '/' has higher precedence than '+'; add parentheses to explicitly specify the order of operations [readability-math-missing-parentheses,-warnings-as-errors]
  545 |         return clone(fn, stack_area + stack_size / 2, flags, arg);
      |                                       ^~~~~~~~~~~~~~~
      |                                       (             )

Just... no.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
---
 Makefile | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 2ebc81e..9afbb74 100644
--- a/Makefile
+++ b/Makefile
@@ -270,6 +270,12 @@ docs: README.md
 #	makes sense when those defines form an enum-like set, but
 #	weird for cases like standalone constants, and causes other
 #	awkwardness for a bunch of cases we use
+#
+# - readability-math-missing-parentheses
+#	It's been a couple of centuries since multiplication has been granted
+#	precedence over addition in modern mathematical notation. Adding
+#	parentheses to reinforce that certainly won't improve readability.
+
 
 clang-tidy: $(filter-out qrap.c,$(SRCS)) $(HEADERS)
 	clang-tidy -checks=*,-modernize-*,\
@@ -296,7 +302,8 @@ clang-tidy: $(filter-out qrap.c,$(SRCS)) $(HEADERS)
 	-concurrency-mt-unsafe,\
 	-readability-identifier-length,\
 	-misc-include-cleaner,\
-	-cppcoreguidelines-macro-to-enum \
+	-cppcoreguidelines-macro-to-enum,\
+	-readability-math-missing-parentheses \
 	-config='{CheckOptions: [{key: bugprone-suspicious-string-compare.WarnOnImplicitComparison, value: "false"}]}' \
 	--warnings-as-errors=* $(filter-out qrap.c,$(SRCS)) -- $(filter-out -pie,$(FLAGS) $(CFLAGS) $(CPPFLAGS)) -DCLANG_TIDY_58992
 
-- 
@@ -270,6 +270,12 @@ docs: README.md
 #	makes sense when those defines form an enum-like set, but
 #	weird for cases like standalone constants, and causes other
 #	awkwardness for a bunch of cases we use
+#
+# - readability-math-missing-parentheses
+#	It's been a couple of centuries since multiplication has been granted
+#	precedence over addition in modern mathematical notation. Adding
+#	parentheses to reinforce that certainly won't improve readability.
+
 
 clang-tidy: $(filter-out qrap.c,$(SRCS)) $(HEADERS)
 	clang-tidy -checks=*,-modernize-*,\
@@ -296,7 +302,8 @@ clang-tidy: $(filter-out qrap.c,$(SRCS)) $(HEADERS)
 	-concurrency-mt-unsafe,\
 	-readability-identifier-length,\
 	-misc-include-cleaner,\
-	-cppcoreguidelines-macro-to-enum \
+	-cppcoreguidelines-macro-to-enum,\
+	-readability-math-missing-parentheses \
 	-config='{CheckOptions: [{key: bugprone-suspicious-string-compare.WarnOnImplicitComparison, value: "false"}]}' \
 	--warnings-as-errors=* $(filter-out qrap.c,$(SRCS)) -- $(filter-out -pie,$(FLAGS) $(CFLAGS) $(CPPFLAGS)) -DCLANG_TIDY_58992
 
-- 
2.43.0