From 43eb1e43b6b22a0343104387431db7f32a88b16c Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Mon, 3 Feb 2025 06:46:29 +0200
Subject: Optimize maybe-used diag_record

It turns out the std::ostringstream member of butl::diag_record is quite
expensive to construct but to never use.
---
 libbuild2/cc/compile-rule.cxx | 28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

(limited to 'libbuild2/cc/compile-rule.cxx')

diff --git a/libbuild2/cc/compile-rule.cxx b/libbuild2/cc/compile-rule.cxx
index c8955bc..53d38ac 100644
--- a/libbuild2/cc/compile-rule.cxx
+++ b/libbuild2/cc/compile-rule.cxx
@@ -2350,9 +2350,9 @@ namespace build2
 
                 if (verb > 2)
                 {
-                  diag_record dr;
-                  dr << error << "header " << f << " not found and no "
-                     << "rule to generate it";
+                  diag_record dr (error);
+                  dr << "header " << f << " not found and no rule to "
+                     << "generate it";
 
                   if (verb < 4)
                     dr << info << "re-run with --verbose=4 for more information";
@@ -2925,8 +2925,8 @@ namespace build2
 
                 if (verb > 2)
                 {
-                  diag_record dr;
-                  dr << error << "header '" << f << "' not found";
+                  diag_record dr (error);
+                  dr << "header '" << f << "' not found";
 
                   if (verb < 4)
                     dr << info << "re-run with --verbose=4 for more information";
@@ -4060,9 +4060,8 @@ namespace build2
           //
           bool df (!ctx.match_only && !ctx.dry_run_option);
 
-          diag_record dr;
-          dr << error << "header " << h << " not found and no rule to "
-             << "generate it";
+          diag_record dr (error);
+          dr << "header " << h << " not found and no rule to generate it";
 
           if (df)
             dr << info << "failure deferred to compiler diagnostics";
@@ -4134,9 +4133,8 @@ namespace build2
           //
           bool df (!ctx.match_only && !ctx.dry_run_option);
 
-          diag_record dr;
-          dr << error << "header " << hp << " not found and no rule to "
-             << "generate it";
+          diag_record dr (error);
+          dr << "header " << hp << " not found and no rule to generate it";
 
           if (df)
             dr << info << "failure deferred to compiler diagnostics";
@@ -4985,7 +4983,7 @@ namespace build2
               if (pr.wait ())
               {
                 {
-                  diag_record dr;
+                  maybe_diag_record dr;
 
                   if (bad_error)
                     dr << fail << "expected error exit status from "
@@ -5093,7 +5091,7 @@ namespace build2
                 // preprocessed source files).
                 //
                 {
-                  diag_record dr;
+                  maybe_diag_record dr;
                   if (force_gen_skip && *force_gen_skip == skip_count)
                   {
                     dr <<
@@ -5101,11 +5099,11 @@ namespace build2
                       info << "run the following two commands to investigate";
 
                     dr << info;
-                    print_process (dr, args.data ()); // No pipes.
+                    print_process (*dr, args.data ()); // No pipes.
 
                     init_args ((gen = true));
                     dr << info << "";
-                    print_process (dr, args.data ()); // No pipes.
+                    print_process (*dr, args.data ()); // No pipes.
                   }
 
                   if (dbuf.is_open ())
-- 
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