From 803bf6493630b0d3597076075736591d83a664ff Mon Sep 17 00:00:00 2001
From: "Richard (Rikki) Andrew Cattermole" <richard@cattermole.co.nz>
Date: Wed, 18 Sep 2024 19:21:07 +1200
Subject: [PATCH] Implement pragma compile on import bugzilla #24869

---
 changelog/dmd.pragma.compileonimport.dd       | 30 +++++++++++++++++++
 compiler/src/dmd/frontend.h                   |  1 +
 compiler/src/dmd/id.d                         |  1 +
 compiler/src/dmd/main.d                       | 24 +++++++--------
 compiler/src/dmd/pragmasem.d                  | 12 ++++++++
 compiler/test/runnable/compileonimport.d      | 10 +++++++
 .../runnable/imports/compileonimportlib.d     |  7 +++++
 7 files changed, 73 insertions(+), 12 deletions(-)
 create mode 100644 changelog/dmd.pragma.compileonimport.dd
 create mode 100644 compiler/test/runnable/compileonimport.d
 create mode 100644 compiler/test/runnable/imports/compileonimportlib.d

diff --git a/changelog/dmd.pragma.compileonimport.dd b/changelog/dmd.pragma.compileonimport.dd
new file mode 100644
index 000000000000..b366ba1c9689
--- /dev/null
+++ b/changelog/dmd.pragma.compileonimport.dd
@@ -0,0 +1,30 @@
+Add a new pragma to compile on import
+
+The pragma ``compileOnImport``, will convert an imported module into one that will be compiled into your binary.
+
+This is the same behavior as the ``-i`` switch, except it is a pragma in a module.
+
+A library module:
+
+```d
+module mylib;
+pragma(compileOnImport);
+
+void callMe() {
+    import std.stdio;
+    writeln("Hello!");
+}
+```
+
+The user module:
+
+```d
+module theuser;
+import mylib;
+
+void main() {
+    callMe(); // Hello!
+}
+```
+
+Compile with ``dmd -I. theuser.d``
diff --git a/compiler/src/dmd/frontend.h b/compiler/src/dmd/frontend.h
index 845e4889e95a..4b4ee557ae12 100644
--- a/compiler/src/dmd/frontend.h
+++ b/compiler/src/dmd/frontend.h
@@ -8583,6 +8583,7 @@ struct Id final
     static Identifier* startaddress;
     static Identifier* crt_constructor;
     static Identifier* crt_destructor;
+    static Identifier* compileOnImport;
     static Identifier* tohash;
     static Identifier* tostring;
     static Identifier* getmembers;
diff --git a/compiler/src/dmd/id.d b/compiler/src/dmd/id.d
index f676361d958b..63a913a77f18 100644
--- a/compiler/src/dmd/id.d
+++ b/compiler/src/dmd/id.d
@@ -352,6 +352,7 @@ immutable Msgtable[] msgtable =
     { "startaddress" },
     { "crt_constructor" },
     { "crt_destructor" },
+    { "compileOnImport" },
 
     // For special functions
     { "tohash", "toHash" },
diff --git a/compiler/src/dmd/main.d b/compiler/src/dmd/main.d
index 27b3e5b8f977..b06173f54e79 100644
--- a/compiler/src/dmd/main.d
+++ b/compiler/src/dmd/main.d
@@ -567,20 +567,20 @@ private int tryMain(size_t argc, const(char)** argv, ref Param params)
             message("semantic3 %s", m.toChars());
         m.semantic3(null);
     }
-    if (includeImports)
+
+    // Will be empty if no module has pragma(compileOnImport) or -i is passed to compiler.
+    // Note: DO NOT USE foreach here because Module.amodules.length can
+    //       change on each iteration of the loop
+    for (size_t i = 0; i < compiledImports.length; i++)
     {
-        // Note: DO NOT USE foreach here because Module.amodules.length can
-        //       change on each iteration of the loop
-        for (size_t i = 0; i < compiledImports.length; i++)
-        {
-            auto m = compiledImports[i];
-            assert(m.isRoot);
-            if (params.v.verbose)
-                message("semantic3 %s", m.toChars());
-            m.semantic3(null);
-            modules.push(m);
-        }
+        auto m = compiledImports[i];
+        assert(m.isRoot);
+        if (params.v.verbose)
+            message("semantic3 %s", m.toChars());
+        m.semantic3(null);
+        modules.push(m);
     }
+
     Module.runDeferredSemantic3();
     if (global.errors)
         removeHdrFilesAndFail(params, modules);
diff --git a/compiler/src/dmd/pragmasem.d b/compiler/src/dmd/pragmasem.d
index 3a455fb3d1a8..76c1f339115b 100644
--- a/compiler/src/dmd/pragmasem.d
+++ b/compiler/src/dmd/pragmasem.d
@@ -320,6 +320,18 @@ void pragmaDeclSemantic(PragmaDeclaration pd, Scope* sc)
             .error(pd.loc, "%s `%s` takes no argument", pd.kind, pd.toPrettyChars);
         return declarations();
     }
+    else if (pd.ident == Id.compileOnImport)
+    {
+        import dmd.compiler;
+
+        if (!sc._module.isRoot())
+        {
+            sc._module.importedFrom = sc._module;
+            compiledImports.push(sc._module);
+        }
+
+        return declarations();
+    }
     else if (!global.params.ignoreUnsupportedPragmas)
     {
         error(pd.loc, "unrecognized `pragma(%s)`", pd.ident.toChars());
diff --git a/compiler/test/runnable/compileonimport.d b/compiler/test/runnable/compileonimport.d
new file mode 100644
index 000000000000..5af110719a81
--- /dev/null
+++ b/compiler/test/runnable/compileonimport.d
@@ -0,0 +1,10 @@
+/*
+REQUIRED_ARGS: -Irunnable/imports
+*/
+module compileonimport;
+import compileonimportlib;
+
+void main() {
+    bool v = runMe();
+    assert(v);
+}
diff --git a/compiler/test/runnable/imports/compileonimportlib.d b/compiler/test/runnable/imports/compileonimportlib.d
new file mode 100644
index 000000000000..ebc12b366989
--- /dev/null
+++ b/compiler/test/runnable/imports/compileonimportlib.d
@@ -0,0 +1,7 @@
+module compileonimportlib;
+
+pragma(compileOnImport);
+
+bool runMe() {
+    return true;
+}