Switch CARBON_CHECK to a format string API (#4285)

This switches `DCHECK` and `FATAL` as well.

The goal is to reduce the code size impact of these assertions so that
we can keep more of them enabled. Currently, the largest cost I see from
`CHECK` is not the actual check or the cold code itself, but actually
the failure to inline trivial functions due to the presence of the cold
code. This means that our goal isn't to reduce apparent code size in the
final binary but the LLVM IR cost assessed for these routines in the
inliner, which closely correlates with code size but is a bit different.

As discussed in #4283, experimentation shows that a single function call
with a minimal number of arguments is the lowest cost model for these.
This is easily achieved with a format-string API that internally uses
`llvm::formatv`. This PR is essentially the `CHECK` version of #4283.

However, the check macros are substantially harder to make work with
both format strings and streaming because they also take a condition.
Also, unexpectedly, I was very successful at devising a regular
expression based automated rewrite from the streaming to the format
string form with only low 10s of manual fixes. This includes compacting
strings broken up across lines, etc. Given how well that went, I've
prepared this PR which just directly switches to the format string API
and migrate everything to use it.

One nice side-effect is that the format string approach ends up greatly
simplifying the implementation here as well.

This is ... *shockingly* effective. Parsing speeds up by more than 3%
with just this change. And checking speeds up by **8%** with this change
alone:
```
BM_CompileAPIFileDenseDecls<Phase::Parse>/256      86.3µs ± 1%  82.9µs ± 1%  -3.94%  (p=0.000 n=17+19)
BM_CompileAPIFileDenseDecls<Phase::Parse>/1024      431µs ± 1%   415µs ± 1%  -3.76%  (p=0.000 n=18+19)
BM_CompileAPIFileDenseDecls<Phase::Parse>/4096     1.77ms ± 1%  1.71ms ± 1%  -3.18%  (p=0.000 n=18+19)
BM_CompileAPIFileDenseDecls<Phase::Parse>/16384    7.44ms ± 1%  7.17ms ± 2%  -3.56%  (p=0.000 n=18+20)
BM_CompileAPIFileDenseDecls<Phase::Parse>/65536    30.7ms ± 1%  29.7ms ± 1%  -3.15%  (p=0.000 n=18+20)
BM_CompileAPIFileDenseDecls<Phase::Parse>/262144    131ms ± 1%   127ms ± 1%  -2.81%  (p=0.000 n=18+18)
BM_CompileAPIFileDenseDecls<Phase::Check>/256       878µs ± 2%   800µs ± 1%  -8.91%  (p=0.000 n=19+20)
BM_CompileAPIFileDenseDecls<Phase::Check>/1024     1.88ms ± 2%  1.72ms ± 1%  -8.56%  (p=0.000 n=19+20)
BM_CompileAPIFileDenseDecls<Phase::Check>/4096     5.78ms ± 2%  5.28ms ± 1%  -8.70%  (p=0.000 n=20+18)
BM_CompileAPIFileDenseDecls<Phase::Check>/16384    21.9ms ± 1%  20.1ms ± 1%  -8.02%  (p=0.000 n=18+20)
BM_CompileAPIFileDenseDecls<Phase::Check>/65536    90.4ms ± 2%  83.1ms ± 1%  -8.04%  (p=0.000 n=19+20)
BM_CompileAPIFileDenseDecls<Phase::Check>/262144    381ms ± 2%   352ms ± 1%  -7.79%  (p=0.000 n=19+19)
```

---------

Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Co-authored-by: josh11b <15258583+josh11b@users.noreply.github.com>

testing/file_test/autoupdate.cpp

@@ -21,8 +21,8 @@ static auto ParseLineNumber(absl::string_view matched_line_number) -> int {
   trimmed = trimmed.trim();
   // NOLINTNEXTLINE(google-runtime-int): API requirement.
   long long val;
-  CARBON_CHECK(!llvm::getAsSignedInteger(trimmed, 10, val))
-      << matched_line_number;
+  CARBON_CHECK(!llvm::getAsSignedInteger(trimmed, 10, val), "{0}",
+               matched_line_number);
   return val;
 }
 
@@ -60,7 +60,7 @@ auto FileTestAutoupdater::CheckLine::RemapLineNumbers(
       RE2::PartialMatch(line_cursor, *replacement_->re, &matched_line_number);
     }
     if (matched_line_number.empty()) {
-      CARBON_CHECK(found_one) << line_;
+      CARBON_CHECK(found_one, "{0}", line_);
       return;
     }
     found_one = true;
@@ -195,9 +195,9 @@ auto FileTestAutoupdater::BuildCheckLines(llvm::StringRef output,
       absl::string_view filename;
       if (RE2::PartialMatch(line, *default_file_re_, &filename)) {
         auto it = file_to_number_map.find(filename);
-        CARBON_CHECK(it != file_to_number_map.end())
-            << "default_file_re had unexpected match in '" << line << "' (`"
-            << default_file_re_->pattern() << "`)";
+        CARBON_CHECK(it != file_to_number_map.end(),
+                     "default_file_re had unexpected match in '{0}' (`{1}`)",
+                     line, default_file_re_->pattern());
         default_file_number = it->second;
       }
     }
@@ -218,7 +218,7 @@ auto FileTestAutoupdater::AddRemappedNonCheckLine() -> void {
 }
 
 auto FileTestAutoupdater::AddTips() -> void {
-  CARBON_CHECK(tips_.empty()) << "Should only add tips once";
+  CARBON_CHECK(tips_.empty(), "Should only add tips once");
 
   tips_.reserve(4);
   // This puts commands on a single line so that they can be easily copied.
@@ -278,12 +278,12 @@ auto FileTestAutoupdater::StartSplitFile() -> void {
   // Advance the file.
   ++output_file_number_;
   output_line_number_ = 0;
-  CARBON_CHECK(output_file_number_ == non_check_line_->file_number())
-      << "Non-sequential file: " << non_check_line_->file_number();
+  CARBON_CHECK(output_file_number_ == non_check_line_->file_number(),
+               "Non-sequential file: {0}", non_check_line_->file_number());
 
   // Each following file has precisely one split line.
-  CARBON_CHECK(non_check_line_->line_number() < 1)
-      << "Expected a split line, got " << *non_check_line_;
+  CARBON_CHECK(non_check_line_->line_number() < 1,
+               "Expected a split line, got {0}", *non_check_line_);
   // The split line is ignored when calculating line counts.
   new_lines_.push_back(non_check_line_);
 
@@ -300,8 +300,8 @@ auto FileTestAutoupdater::Run(bool dry_run) -> bool {
   // Print everything until the autoupdate line.
   while (non_check_line_->line_number() != autoupdate_line_number_) {
     CARBON_CHECK(non_check_line_ != non_check_lines_.end() &&
-                 non_check_line_->file_number() == 0)
-        << "Missed autoupdate?";
+                     non_check_line_->file_number() == 0,
+                 "Missed autoupdate?");
     AddRemappedNonCheckLine();
     ++non_check_line_;
   }