From 81a3f81c046697ff011c93929c75c29f4cd39f2f Mon Sep 17 00:00:00 2001
From: Gaëtan Gilbert
Date: Sun, 15 Nov 2020 21:08:11 +0100
Subject: Intern application arguments in left-to-right order

This makes it so that we have an application `h a b` with both `a` and
`b` unbound, `a` is the one that is reported (parent commit with my current
compiler setup reports `b` first, and the code does not define which
it should be).

Ideally we would report both but that requires more code.
---
 interp/constrintern.ml           | 5 +++--
 test-suite/output/UnboundRef.out | 3 +++
 test-suite/output/UnboundRef.v   | 2 ++
 3 files changed, 8 insertions(+), 2 deletions(-)
 create mode 100644 test-suite/output/UnboundRef.out
 create mode 100644 test-suite/output/UnboundRef.v

diff --git a/interp/constrintern.ml b/interp/constrintern.ml
index 378617af04..9f10991510 100644
--- a/interp/constrintern.ml
+++ b/interp/constrintern.ml
@@ -2405,8 +2405,9 @@ let internalize globalenv env pattern_mode (_, ntnvars as lvar) c =
   and intern_args env subscopes = function
     | [] -> []
     | a::args ->
-        let (enva,subscopes) = apply_scope_env env subscopes in
-        (intern_no_implicit enva a) :: (intern_args env subscopes args)
+      let (enva,subscopes) = apply_scope_env env subscopes in
+      let a = intern_no_implicit enva a in
+      a :: (intern_args env subscopes args)
 
   in
   intern env c
diff --git a/test-suite/output/UnboundRef.out b/test-suite/output/UnboundRef.out
new file mode 100644
index 0000000000..a574e97e0f
--- /dev/null
+++ b/test-suite/output/UnboundRef.out
@@ -0,0 +1,3 @@
+File "stdin", line 1, characters 11-12:
+Error: The reference a was not found in the current environment.
+
diff --git a/test-suite/output/UnboundRef.v b/test-suite/output/UnboundRef.v
new file mode 100644
index 0000000000..fd08ae0c5c
--- /dev/null
+++ b/test-suite/output/UnboundRef.v
@@ -0,0 +1,2 @@
+Check Prop a b.
+(* Prop is because we need a real head for the application *)
-- 
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