From b8efee444cbfb6c370fb68f52bbcf266ed2f65a8 Mon Sep 17 00:00:00 2001
From: metagn <metagngn@gmail.com>
Date: Tue, 8 Oct 2024 00:18:45 +0300
Subject: [PATCH] process non-language pragma nodes in generics (#24254)

fixes #18649, refs #24183

Same as in #24183 for templates, we now process pragma nodes in generics
so that macro symbols are captured and the pragma arguments are checked,
but ignoring language pragma keywords.

A difference is that we cannot process call nodes as is, we have to
process their children individually so that the early untyped
macro/template instantiation in generics does not kick in.

(cherry picked from commit d72b848d1799191b4b5535336b3a708205374b31)
---
 compiler/semgnrc.nim        | 19 ++++++++++++++++++-
 tests/generics/mpragma1.nim |  3 +++
 tests/generics/mpragma2.nim |  6 ++++++
 tests/generics/tpragma.nim  | 10 ++++++++++
 4 files changed, 37 insertions(+), 1 deletion(-)
 create mode 100644 tests/generics/mpragma1.nim
 create mode 100644 tests/generics/mpragma2.nim
 create mode 100644 tests/generics/tpragma.nim

diff --git a/compiler/semgnrc.nim b/compiler/semgnrc.nim
index 2639aba6cb..74f77a679c 100644
--- a/compiler/semgnrc.nim
+++ b/compiler/semgnrc.nim
@@ -616,7 +616,24 @@ proc semGenericStmt(c: PContext, n: PNode,
     let bodyFlags = if n.kind == nkTemplateDef: flags + {withinMixin} else: flags
     n[bodyPos] = semGenericStmtScope(c, body, bodyFlags, ctx)
     closeScope(c)
-  of nkPragma, nkPragmaExpr: discard
+  of nkPragmaExpr:
+    result[1] = semGenericStmt(c, n[1], flags, ctx)
+  of nkPragma:
+    for i in 0 ..< n.len:
+      let x = n[i]
+      let prag = whichPragma(x)
+      if x.kind in nkPragmaCallKinds:
+        # process each child individually to prevent untyped macros/templates
+        # from instantiating
+        # if pragma is language-level pragma, skip name node:
+        let start = ord(prag != wInvalid)
+        for j in start ..< x.len:
+          # treat as mixin context for user pragmas & macro args
+          x[j] = semGenericStmt(c, x[j], flags+{withinMixin}, ctx)
+      elif prag == wInvalid:
+        # only sem if not a language-level pragma 
+        # treat as mixin context for user pragmas & macro args
+        result[i] = semGenericStmt(c, x, flags+{withinMixin}, ctx)
   of nkExprColonExpr, nkExprEqExpr:
     checkMinSonsLen(n, 2, c.config)
     result[1] = semGenericStmt(c, n[1], flags, ctx)
diff --git a/tests/generics/mpragma1.nim b/tests/generics/mpragma1.nim
new file mode 100644
index 0000000000..138d035df1
--- /dev/null
+++ b/tests/generics/mpragma1.nim
@@ -0,0 +1,3 @@
+macro aMacro*(u:untyped):untyped =
+  echo "in macro"
+  result = u
diff --git a/tests/generics/mpragma2.nim b/tests/generics/mpragma2.nim
new file mode 100644
index 0000000000..3c7251daf8
--- /dev/null
+++ b/tests/generics/mpragma2.nim
@@ -0,0 +1,6 @@
+import mpragma1
+proc p*[T]() =
+  proc inner() {.aMacro.} =
+    discard
+  inner()
+  discard
diff --git a/tests/generics/tpragma.nim b/tests/generics/tpragma.nim
new file mode 100644
index 0000000000..e83ef9cf45
--- /dev/null
+++ b/tests/generics/tpragma.nim
@@ -0,0 +1,10 @@
+discard """
+  nimout: '''
+in macro
+'''
+"""
+
+# issue #18649
+
+import mpragma2
+p[string]()