From 9db5a11428bb28988c7e868e4d9d5c603f0b9e26 Mon Sep 17 00:00:00 2001
From: Cedric St-Jean <cedric.stjean@gmail.com>
Date: Mon, 25 Dec 2023 06:38:08 +0900
Subject: [PATCH] Define @qq

---
 docs/src/utilities.md |  1 +
 src/utils.jl          | 23 +++++++++++++++++++++++
 test/utils.jl         | 16 +++++++++++++++-
 3 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/docs/src/utilities.md b/docs/src/utilities.md
index 58dc89c..6ac3243 100644
--- a/docs/src/utilities.md
+++ b/docs/src/utilities.md
@@ -43,6 +43,7 @@ MacroTools.combinearg
 
 ```@docs
 MacroTools.@q
+MacroTools.@qq
 MacroTools.isexpr
 MacroTools.rmlines
 MacroTools.unblock
diff --git a/src/utils.jl b/src/utils.jl
index 4d1aca2..9b7a48b 100644
--- a/src/utils.jl
+++ b/src/utils.jl
@@ -36,6 +36,29 @@ macro q(ex)
   esc(Expr(:quote, striplines(ex)))
 end
 
+struct Flag end
+
+to_flag(ex) = MacroTools.prewalk(x->x isa LineNumberNode ? Flag() : x, ex)
+to_line(l::LineNumberNode, ex) = MacroTools.prewalk(x->x isa Flag ? l : x, ex)
+
+"""
+    @qq [expression]
+
+Like the `quote` keyword but replace construction site line numbers with __source__.
+Line numbers of interpolated expressions are preserved. The result is that line numbers will be
+attributed to the macro usage site, instead of the macro source code.
+
+Only works inside of a macro definition.
+
+See also: [`@q`](@ref)
+"""
+macro qq(ex)
+    # This was a difficult macro to write; the round-trip to Flag appears to be necessary.
+    # Crucially, we want interpolated expressions to preserve their line numbers.
+    esc(:($MacroTools.to_line(__source__, $(Expr(:quote, to_flag(ex))))))
+end
+
+
 """
     isexpr(x, ts...)
 
diff --git a/test/utils.jl b/test/utils.jl
index 84e962c..f468845 100644
--- a/test/utils.jl
+++ b/test/utils.jl
@@ -1,4 +1,4 @@
-using MacroTools: isdef, flatten, striplines
+using MacroTools: isdef, flatten, striplines, @qq
 
 @testset "utils" begin
     ex1 = :(function foo(a) return a; end)
@@ -45,3 +45,17 @@ end
         @test flatten(ex) |> striplines == ex |> striplines
     end
 end
+
+## Test for @qq
+
+macro my_fff_def(a)
+    @qq function fff() $a end
+end
+
+@my_fff_def begin   # line where fff() is defined
+    function g()    # line where fff()() is defined
+        22
+    end
+end
+
+@test which(fff,()).line == which(fff(),()).line - 1