From b9d0839c6e9bc586e2862ff9457ac582354b8347 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Mon, 27 Apr 2020 09:46:34 +0200
Subject: Require explicit variable type in scope::{assign,append}()

---
 libbuild2/scope.hxx        | 65 +++++++++++++++++++++++++++-------------------
 libbuild2/version/init.cxx |  9 ++++---
 2 files changed, 44 insertions(+), 30 deletions(-)

diff --git a/libbuild2/scope.hxx b/libbuild2/scope.hxx
index 39be143..e1cdf78 100644
--- a/libbuild2/scope.hxx
+++ b/libbuild2/scope.hxx
@@ -187,6 +187,22 @@ namespace build2
     value&
     assign (const variable* var) {return vars.assign (var);} // For cached.
 
+    template <typename T>
+    T&
+    assign (const variable& var, T&& val)
+    {
+      value& v (assign (var) = forward<T> (val));
+      return v.as<T> ();
+    }
+
+    template <typename T>
+    T&
+    assign (const variable* var, T&& val)
+    {
+      value& v (assign (var) = forward<T> (val));
+      return v.as<T> ();
+    }
+
     // Assign an untyped non-overridable variable with project visibility.
     //
     value&
@@ -195,47 +211,44 @@ namespace build2
       return assign (var_pool ().insert (move (name)));
     }
 
-    // As above, but assign a typed variable.
+    // As above, but assign a typed variable (note: variable type must be
+    // specified explicitly).
     //
-    template <typename T>
+    template <typename V>
     value&
     assign (string name)
     {
-      return vars.assign (var_pool ().insert<T> (move (name)));
+      return vars.assign (var_pool ().insert<V> (move (name)));
     }
 
-    template <typename T>
-    T&
+    template <typename V, typename T>
+    V&
     assign (string name, T&& val)
     {
-      value& v (assign<T> (move (name)) = forward<T> (val));
-      return v.as<T> ();
+      value& v (assign<V> (move (name)) = forward<T> (val));
+      return v.as<V> ();
     }
 
-    template <typename T>
-    T&
-    assign (const variable& var, T&& val)
-    {
-      value& v (assign (var) = forward<T> (val));
-      return v.as<T> ();
-    }
+    // Return a value suitable for appending. If the variable does not exist
+    // in this scope's map, then outer scopes are searched for the same
+    // variable. If found then a new variable with the found value is added to
+    // this scope and returned. Otherwise this function proceeds as assign().
+    //
+    value&
+    append (const variable&);
 
-    template <typename T>
-    T&
-    assign (const variable* var, T&& val)
+    value&
+    append (string name)
     {
-      value& v (assign (var) = forward<T> (val));
-      return v.as<T> ();
+      return append (var_pool ().insert (move (name)));
     }
 
-    // Return a value suitable for appending. If the variable does not
-    // exist in this scope's map, then outer scopes are searched for
-    // the same variable. If found then a new variable with the found
-    // value is added to this scope and returned. Otherwise this
-    // function proceeds as assign().
-    //
+    template <typename V>
     value&
-    append (const variable&);
+    append (string name)
+    {
+      return append (var_pool ().insert<V> (move (name)));
+    }
 
     // Target type/pattern-specific variables.
     //
diff --git a/libbuild2/version/init.cxx b/libbuild2/version/init.cxx
index d30dc24..7c5d589 100644
--- a/libbuild2/version/init.cxx
+++ b/libbuild2/version/init.cxx
@@ -226,13 +226,14 @@ namespace build2
       // Note also that we have "gifted" the config.version variable name to
       // the config module.
       //
-      auto set = [&rs] (auto var, auto val)
+      auto set = [&rs] (const char* var, auto val)
       {
-        rs.assign (var, move (val));
+        using T = decltype (val);
+        rs.assign<T> (var, move (val));
       };
 
-      if (!sum.empty ()) set (ctx.var_project_summary, move (sum));
-      if (!url.empty ()) set (ctx.var_project_url,     move (url));
+      if (!sum.empty ()) rs.assign (ctx.var_project_summary, move (sum));
+      if (!url.empty ()) rs.assign (ctx.var_project_url,     move (url));
 
       set ("version", v.string ());  // Project version (var_version).
 
-- 
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