From bb25d82a3bd83a479ac511d6d23a55a117804a2c Mon Sep 17 00:00:00 2001
From: Martin Kinkelin <kinke@users.noreply.github.com>
Date: Thu, 10 Apr 2025 23:03:54 +0200
Subject: [PATCH] build.d: Fix dependencies on generated string-import files
 (#21192)

This is just a byproduct of taking a closer look at this code,
as part of investigating the recent CI failures on Windows, where
the VERSION and SYSCONFDIR.imp rules seem to run twice - and then
fail for the 2nd run, Windows complaining about another process using
the file. I guess that could be an Anti-malware process running right
after creating the file the first time. And both rules check the file
contents as part of their condition, so if the rule is processed twice,
we try to immediately read its contents after the write.

Each of these 2 auto-generated files is string-imported exactly once:

* `SYSCONFDIR.imp` in the driver's `dmd/dinifile.d` (and actually on
  Posix only)
* `VERSION` in the lexer's `dmd/globals.d`

I've revised the deps accordingly, which might avoid processing these
rules multiple times as a side-effect.
---
 compiler/src/build.d | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/compiler/src/build.d b/compiler/src/build.d
index 18dd9a531d..2bc12af6b4 100755
--- a/compiler/src/build.d
+++ b/compiler/src/build.d
@@ -263,7 +263,6 @@ alias lexer = makeRuleWithArgs!((MethodInitializer!BuildRule builder, BuildRule
     .sources(sources.lexer)
     .deps([
         versionFile,
-        sysconfDirFile,
         common(suffix, extraFlags)
     ])
     .msg("(DC) LEXER" ~ suffix)
@@ -378,7 +377,7 @@ alias backend = makeRuleWithArgs!((MethodInitializer!BuildRule builder, BuildRul
         ).array)
 );
 
-/// Returns: the rules that generate required string files: VERSION and SYSCONFDIR.imp
+/// Returns: the rule that generates string-import file `VERSION` (for the lexer)
 alias versionFile = makeRule!((builder, rule) {
     alias contents = memoize!(() {
         if (dmdRepo.buildPath(".git").exists)
@@ -420,6 +419,7 @@ alias versionFile = makeRule!((builder, rule) {
     .commandFunction(() => writeText(rule.target, contents));
 });
 
+/// Returns: the rule that generates string-import file `SYSCONFDIR.imp` (for the driver)
 alias sysconfDirFile = makeRule!((builder, rule) => builder
     .target(env["G"].buildPath("SYSCONFDIR.imp"))
     .condition(() => !rule.target.exists || rule.target.readText != env["SYSCONFDIR"])
@@ -469,7 +469,7 @@ alias dmdExe = makeRuleWithArgs!((MethodInitializer!BuildRule builder, BuildRule
         .sources(dmdSources.chain(lexer.targets, backend.targets, common.targets).array)
         .target(env["DMD_PATH"] ~ targetSuffix)
         .msg("(DC) DMD" ~ targetSuffix)
-        .deps([lexer, backend, common])
+        .deps([sysconfDirFile, lexer, backend, common])
         .command([
             env["HOST_DMD_RUN"],
             "-of" ~ rule.target,
@@ -757,13 +757,15 @@ alias runCxxUnittest = makeRule!((runCxxBuilder, runCxxRule) {
         .name("cxx-unittest")
         .description("Build the C++ unittests")
         .msg("(DC) CXX-UNITTEST")
-        .deps([lexer(null, null), cxxFrontend])
+        .deps([sysconfDirFile, lexer(null, null), cxxFrontend])
         .sources(sources.dmd.driver ~ sources.dmd.frontend ~ sources.root ~ sources.common ~ env["D"].buildPath("cxxfrontend.d"))
         .target(env["G"].buildPath("cxx-unittest").exeName)
         .command([ env["HOST_DMD_RUN"], "-of=" ~ exeRule.target, "-vtls", "-J" ~ env["RES"],
                     "-L-lstdc++", "-version=NoMain", "-version=NoBackend"
             ].chain(
-                flags["DFLAGS"], exeRule.sources, exeRule.deps.map!(d => d.target)
+                flags["DFLAGS"], exeRule.sources,
+                // don't compile deps[0], the SYSCONFDIR.imp string-import file
+                exeRule.deps[1 .. $].map!(d => d.target)
             ).array)
     );
 
@@ -967,7 +969,7 @@ alias html = makeRule!((htmlBuilder, htmlRule) {
             .sources(sourceArray)
             .target(env["DOC_OUTPUT_DIR"].buildPath(d2html(source)[srcDir.length + 1..$]
                 .replace(dirSeparator, "_")))
-            .deps([dmdDefault, versionFile, sysconfDirFile])
+            .deps([dmdDefault])
             .command([
                 dmdDefault.deps[0].target,
                 "-o-",