From 4177d70e63893d0a2c76beb9166ebbf79c4697a0 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Mon, 26 Aug 2019 15:38:23 +0200
Subject: Add support for for_install prerequisite-specific var in link rule

Also reserve for_test.
---
 build2/cc/link-rule.cxx    | 25 +++++++++++++++++++++++++
 build2/cc/link-rule.hxx    |  1 +
 libbuild2/install/init.cxx |  1 +
 libbuild2/test/init.cxx    |  4 ++++
 4 files changed, 31 insertions(+)

diff --git a/build2/cc/link-rule.cxx b/build2/cc/link-rule.cxx
index bfc31d7..fa6d5e4 100644
--- a/build2/cc/link-rule.cxx
+++ b/build2/cc/link-rule.cxx
@@ -1299,6 +1299,7 @@ namespace build2
       }
 
       md.binless = binless;
+      md.start = start;
 
       switch (a)
       {
@@ -1801,6 +1802,30 @@ namespace build2
         ts = target_state::changed;
       }
 
+      // Check for the for_install variable on each prerequisite and blank out
+      // those that don't match. Note that we have to do it after updating
+      // prerequisites to keep the dependency counts straight.
+      //
+      if (const variable* var_fi = ctx.var_pool.find ("for_install"))
+      {
+        // Parallel prerequisites/prerequisite_targets loop.
+        //
+        size_t i (md.start);
+        for (prerequisite_member p: group_prerequisite_members (a, t))
+        {
+          const target*& pt (t.prerequisite_targets[a][i++]);
+
+          if (pt == nullptr)
+            continue;
+
+          if (lookup l = p.prerequisite.vars[var_fi])
+          {
+            if (cast<bool> (l) != for_install)
+              pt = nullptr;
+          }
+        }
+      }
+
       // (Re)generate pkg-config's .pc file. While the target itself might be
       // up-to-date from a previous run, there is no guarantee that .pc exists
       // or also up-to-date. So to keep things simple we just regenerate it
diff --git a/build2/cc/link-rule.hxx b/build2/cc/link-rule.hxx
index c572ab3..da6181b 100644
--- a/build2/cc/link-rule.hxx
+++ b/build2/cc/link-rule.hxx
@@ -116,6 +116,7 @@ namespace build2
         optional<bool> for_install;
 
         bool binless; // Binary-less library.
+        size_t start; // Parallel prerequisites/prerequisite_targets start.
 
         link_rule::libs_paths libs_paths;
       };
diff --git a/libbuild2/install/init.cxx b/libbuild2/install/init.cxx
index d2321b5..445f2b1 100644
--- a/libbuild2/install/init.cxx
+++ b/libbuild2/install/init.cxx
@@ -209,6 +209,7 @@ namespace build2
         // the trailing directory separator.
         //
         vp.insert<path>   ("install",         variable_visibility::target);
+        vp.insert<bool>   ("for_install",     variable_visibility::prereq);
         vp.insert<string> ("install.mode",    variable_visibility::project);
         vp.insert<bool>   ("install.subdirs", variable_visibility::project);
       }
diff --git a/libbuild2/test/init.cxx b/libbuild2/test/init.cxx
index 923f047..5681b37 100644
--- a/libbuild2/test/init.cxx
+++ b/libbuild2/test/init.cxx
@@ -97,6 +97,10 @@ namespace build2
         vp.insert<target_triplet> ("test.target", variable_visibility::project)
       };
 
+      // This one is used by other modules/rules.
+      //
+      vp.insert<bool> ("for_test", variable_visibility::prereq);
+
       // These are only used in testscript.
       //
       vp.insert<strings> ("test.redirects", variable_visibility::project);
-- 
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