From 0353b231d51ab7ea5ead98ac838e7c2ba1b0df89 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Tue, 20 Apr 2021 11:19:28 +0200
Subject: Track changes to environment in cc rules

---
 libbuild2/cc/common.hxx       |  4 ++++
 libbuild2/cc/compile-rule.cxx |  7 ++++++-
 libbuild2/cc/link-rule.cxx    | 11 +++++++----
 libbuild2/cc/module.cxx       | 14 ++++++++++++++
 libbuild2/cc/module.hxx       |  2 ++
 5 files changed, 33 insertions(+), 5 deletions(-)

(limited to 'libbuild2/cc')

diff --git a/libbuild2/cc/common.hxx b/libbuild2/cc/common.hxx
index 612d081..758c675 100644
--- a/libbuild2/cc/common.hxx
+++ b/libbuild2/cc/common.hxx
@@ -170,6 +170,8 @@ namespace build2
       const string& tsys;           // x.target.system
       const string& tclass;         // x.target.class
 
+      const string& env_checksum;   // config_module::env_checksum
+
       bool modules;                 // x.features.modules
       bool symexport;               // x.features.symexport
 
@@ -230,6 +232,7 @@ namespace build2
             const process_path& path,
             const strings& mode,
             const target_triplet& tgt,
+            const string& env_cs,
             bool fm,
             bool fs,
             const dir_paths& sld,
@@ -250,6 +253,7 @@ namespace build2
             cmaj (mj), cmin (mi),
             cpath (path), cmode (mode),
             ctgt (tgt), tsys (ctgt.system), tclass (ctgt.class_),
+            env_checksum (env_cs),
             modules (fm),
             symexport (fs),
             importable_headers (nullptr),
diff --git a/libbuild2/cc/compile-rule.cxx b/libbuild2/cc/compile-rule.cxx
index b5016bc..ce586bb 100644
--- a/libbuild2/cc/compile-rule.cxx
+++ b/libbuild2/cc/compile-rule.cxx
@@ -197,7 +197,7 @@ namespace build2
     compile_rule::
     compile_rule (data&& d)
         : common (move (d)),
-          rule_id (string (x) += ".compile 4")
+          rule_id (string (x) += ".compile 5")
     {
       static_assert (sizeof (match_data) <= target::data_size,
                      "insufficient space");
@@ -929,6 +929,11 @@ namespace build2
         if (dd.expect (cast<string> (rs[x_checksum])) != nullptr)
           l4 ([&]{trace << "compiler mismatch forcing update of " << t;});
 
+        // Then the compiler environment checksum.
+        //
+        if (dd.expect (env_checksum) != nullptr)
+          l4 ([&]{trace << "environment mismatch forcing update of " << t;});
+
         // Then the options checksum.
         //
         // The idea is to keep them exactly as they are passed to the compiler
diff --git a/libbuild2/cc/link-rule.cxx b/libbuild2/cc/link-rule.cxx
index 9c72969..0ab61b1 100644
--- a/libbuild2/cc/link-rule.cxx
+++ b/libbuild2/cc/link-rule.cxx
@@ -37,7 +37,7 @@ namespace build2
     link_rule::
     link_rule (data&& d)
         : common (move (d)),
-          rule_id (string (x) += ".link 2")
+          rule_id (string (x) += ".link 3")
     {
       static_assert (sizeof (match_data) <= target::data_size,
                      "insufficient space");
@@ -2427,10 +2427,13 @@ namespace build2
           l4 ([&]{trace << "linker mismatch forcing update of " << t;});
       }
 
-      // Hash and compare any changes to the environment.
+      // Then the linker environment checksum (original and our modifications).
       //
-      if (dd.expect (env_cs.string ()) != nullptr)
-        l4 ([&]{trace << "environment mismatch forcing update of " << t;});
+      {
+        bool e (dd.expect (env_checksum) != nullptr);
+        if (dd.expect (env_cs.string ()) != nullptr || e)
+          l4 ([&]{trace << "environment mismatch forcing update of " << t;});
+      }
 
       // Next check the target. While it might be incorporated into the linker
       // checksum, it also might not (e.g., VC link.exe).
diff --git a/libbuild2/cc/module.cxx b/libbuild2/cc/module.cxx
index 5bb3f60..7ef8cd5 100644
--- a/libbuild2/cc/module.cxx
+++ b/libbuild2/cc/module.cxx
@@ -202,8 +202,22 @@ namespace build2
         }
       }
 
+      // Hash the environment (used for change detection).
+      //
+      // Note that for simplicity we use the combined checksum for both
+      // compilation and linking (which may compile, think LTO).
+      //
+      {
+        sha256 cs;
+        hash_environment (cs, xi.compiler_environment);
+        hash_environment (cs, xi.platform_environment);
+        env_checksum = cs.string ();
+      }
+
       // Assign values to variables that describe the compiler.
       //
+      // @@ TODO: env_checksum.
+      //
       rs.assign (x_path) = process_path_ex (xi.path, x_name, xi.checksum);
       const strings& xm (cast<strings> (rs.assign (x_mode) = move (mode)));
 
diff --git a/libbuild2/cc/module.hxx b/libbuild2/cc/module.hxx
index f9d435d..ed6ec41 100644
--- a/libbuild2/cc/module.hxx
+++ b/libbuild2/cc/module.hxx
@@ -59,6 +59,8 @@ namespace build2
 
       const compiler_info* x_info;
 
+      string env_checksum; // Environment checksum (also in x.path).
+
       // Temporary storage for data::sys_*_dirs_*.
       //
       size_t sys_lib_dirs_mode;
-- 
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