From 331c61e385b5d5b43a320666fd49ff30dea1548e Mon Sep 17 00:00:00 2001
From: Nicholas Wilson <iamthewilsonator@hotmail.com>
Date: Wed, 27 Sep 2023 16:02:04 +0800
Subject: [PATCH] implement `pragma(__ctfe [,bool])`

---
 dmd/dsymbolsem.d   | 16 ++++++++++++--
 dmd/statementsem.d | 53 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+), 2 deletions(-)

diff --git a/dmd/dsymbolsem.d b/dmd/dsymbolsem.d
index a777d695dde..5915f2b97f2 100644
--- a/dmd/dsymbolsem.d
+++ b/dmd/dsymbolsem.d
@@ -1711,7 +1711,7 @@ version (IN_LLVM)
             }
             return se;
         }
-        void declarations()
+        void declarations(bool skipCodegen = false)
         {
             if (!pd.decl)
                 return;
@@ -1729,7 +1729,13 @@ version (IN_LLVM)
                     s.dsymbolSemantic(sc2);
                     continue;
                 }
-
+                if (pd.ident == Id.ctfe)
+                {
+                    if (auto fd = s.isFuncDeclaration())
+                    {
+                        fd.skipCodegen = skipCodegen;
+                    }
+                }
                 s.dsymbolSemantic(sc2);
                 if (pd.ident != Id.mangle)
                 {
@@ -1893,6 +1899,12 @@ else // !IN_LLVM
 
             return declarations();
         }
+        else if (pd.ident == Id.ctfe)
+        {
+            bool skipCodegen;
+            pragmaCtfeSemanitc(pd.loc, sc, pd.args, skipCodegen);
+            return declarations(skipCodegen);
+        }
         else if (pd.ident == Id.mangle)
         {
             if (!pd.args)
diff --git a/dmd/statementsem.d b/dmd/statementsem.d
index c35449a6897..3e1369058dc 100644
--- a/dmd/statementsem.d
+++ b/dmd/statementsem.d
@@ -1844,6 +1844,21 @@ Statement statementSemanticVisit(Statement s, Scope* sc)
                 return setError();
             }
         }
+        else if (ps.ident == Id.ctfe)
+        {
+            if (auto fd = sc.func)
+            {
+                bool skipCodegen;
+                if (!pragmaCtfeSemanitc(ps.loc, sc, ps.args, skipCodegen))
+                    return setError();
+                fd.skipCodegen = skipCodegen;
+            }
+            else
+            {
+                ps.error("`pragma(__ctfe)` is not inside a function");
+                return setError();
+            }
+        }
         else if (!global.params.ignoreUnsupportedPragmas)
         {
             ps.error("unrecognized `pragma(%s)`", ps.ident.toChars());
@@ -5033,6 +5048,44 @@ private void debugThrowWalker(Statement s)
     s.accept(walker);
 }
 
+bool pragmaCtfeSemanitc(Loc loc, Scope* sc, Expressions *args, out bool skipCodegen)
+{
+    if (!args)
+    {
+        skipCodegen = true;
+        return true;
+    }
+    if (args.length != 1)
+    {
+        .error(loc, "one `bool` argument expected for `__ctfe`");
+        skipCodegen = true;
+        return false;
+    }
+    Expression e = (*args)[0];
+    sc = sc.startCTFE();
+    e = e.expressionSemantic(sc);
+    e = resolveProperties(sc, e);
+    sc = sc.endCTFE();
+
+    e = e.ctfeInterpret();
+    if (!e)
+    {
+        skipCodegen = true;
+        return false;
+    }
+    (*args)[0] = e;
+    auto opt = e.toBool();
+    if (opt.isEmpty())
+    {
+        .error(loc, "one `bool` argument expected for `__ctfe`");
+        skipCodegen = true;
+        return false;
+    }
+    skipCodegen = opt.get();
+    return true;
+    
+}
+
 /***********************************************************
  * Evaluate and print a `pragma(msg, args)`
  *