Improve diagnostics

2 files changed, 15 insertions, 1 deletions

diff --git a/libbuild2/parser.cxx b/libbuild2/parser.cxx
index 5572104..2623bf3 100644
--- a/libbuild2/parser.cxx
+++ b/libbuild2/parser.cxx
@@ -6257,7 +6257,7 @@ namespace build2
                           type kind)
   {
     attributes as (attributes_pop ());
-    const location& l (as.loc);
+    const location& l (as.loc); // This points to value if no attributes.
 
     // Essentially this is an attribute-augmented assign/append/prepend.
     //
@@ -6376,6 +6376,17 @@ namespace build2
     }
     else
     {
+      auto df = make_diag_frame (
+        [this, var, &l](const diag_record& dr)
+        {
+          if (!l.empty ())
+          {
+            dr << info (l);
+            if (var != nullptr) dr << "variable " << var->name << ' ';
+            dr << "value is assigned here";
+          }
+        });
+
       if (kind == type::assign)
       {
         if (rhs)
diff --git a/tests/type/json/testscript b/tests/type/json/testscript
index 6dd6316..6beaf5d 100644
--- a/tests/type/json/testscript
+++ b/tests/type/json/testscript
@@ -91,6 +91,7 @@
   o = [json] '{"one":1, "two":}'
   EOI
   error: invalid json value in variable o: invalid json input: unexpected byte '}' in value
+    <stdin>:1:5: info: variable o value is assigned here
   EOE
 
   : diagnostics-duplicate-member
@@ -99,6 +100,7 @@
   o = [json] one@1 one@2
   EOI
   error: invalid json value in variable o: duplicate json object member 'one'
+    <stdin>:1:5: info: variable o value is assigned here
   EOE
 }
 
@@ -277,6 +279,7 @@
   print $s
   EOI
   error: invalid json value in variable s: unable to append array to string
+    <stdin>:3:6: info: variable s value is assigned here
   EOE
 }