From 4e0bf1b76aebbf7b86f3445960d7402925fd0ae6 Mon Sep 17 00:00:00 2001
From: Walter Bright <walter@walterbright.com>
Date: Fri, 20 May 2022 09:50:15 -0700
Subject: [PATCH] ImportC add Windows cl preprocessor #define support

---
 src/dmd/cparse.d                              |  9 +++-
 src/dmd/link.d                                | 51 ++++++++++++++-----
 .../{testdefines.c => imports/defines.c}      |  2 +-
 test/compilable/testdefines.d                 |  4 ++
 4 files changed, 51 insertions(+), 15 deletions(-)
 rename test/compilable/{testdefines.c => imports/defines.c} (59%)
 create mode 100644 test/compilable/testdefines.d

diff --git a/src/dmd/cparse.d b/src/dmd/cparse.d
index 8bcd35e1b621..344933ace83c 100644
--- a/src/dmd/cparse.d
+++ b/src/dmd/cparse.d
@@ -5156,6 +5156,11 @@ final class CParser(AST) : Parser!AST
                 {
                     auto id = n.ident;
                     scan(&n);
+                    if (n.value == TOK.endOfLine)       // #define identifier
+                    {
+                        nextDefineLine();
+                        continue;
+                    }
                     if (n.value == TOK.int32Literal)
                     {
                         const value = n.intvalue;
@@ -5168,12 +5173,14 @@ final class CParser(AST) : Parser!AST
                             AST.Expression e = new AST.IntegerExp(scanloc, value, AST.Type.tint32);
                             auto v = new AST.VarDeclaration(scanloc, AST.Type.tint32, id, new AST.ExpInitializer(scanloc, e), STC.manifest);
                             symbols.push(v);
+                            nextDefineLine();
+                            continue;
                         }
                     }
                 }
                 skipToNextLine();
             }
-            else
+            else if (n.value != TOK.endOfLine)
             {
                 skipToNextLine();
             }
diff --git a/src/dmd/link.d b/src/dmd/link.d
index 020505b771d3..0968d7b0d7ae 100644
--- a/src/dmd/link.d
+++ b/src/dmd/link.d
@@ -1058,7 +1058,7 @@ public int runPreprocessor(const(char)[] cpp, const(char)[] filename, const(char
                  */
                 OutBuffer buf;
                 buf.writestring(cpp);
-                buf.printf(" /P /nologo %.*s /FI%s /Fi%.*s",
+                buf.printf(" /P /Zc:preprocessor /PD /nologo %.*s /FI%s /Fi%.*s",
                     cast(int)filename.length, filename.ptr, importc_h, cast(int)output.length, output.ptr);
 
                 /* Append preprocessor switches to command line
@@ -1077,24 +1077,46 @@ public int runPreprocessor(const(char)[] cpp, const(char)[] filename, const(char
 
                 ubyte[2048] buffer = void;
 
-                bool firstLine = true;
+                OutBuffer linebuf;      // each line from stdout
+                bool print = false;     // print line collected from stdout
+
+                /* Collect text captured from stdout to linebuf[].
+                 * Then decide to print or discard the contents.
+                 * Discarding lines that consist only of a filename is necessary to pass
+                 * the D test suite which diffs the output. CL's emission of filenames cannot
+                 * be turned off.
+                 */
                 void sink(ubyte[] data)
                 {
-                    if (firstLine)
+                    foreach (c; data)
                     {
-                        for (size_t i = 0; 1; ++i)
+                        switch (c)
                         {
-                            if (i == data.length)
-                                return;
-                            if (data[i] == '\n')        // reached end of first line
-                            {
-                                data = data[i + 1 .. data.length];
-                                firstLine = false;
+                            case '\r':
+                                break;
+
+                            case '\n':
+                                if (print)
+                                    printf("%s\n", linebuf.peekChars());
+
+                                // set up for next line
+                                linebuf.setsize(0);
+                                print = false;
+                                break;
+
+                            case '\t':
+                            case ';':
+                            case '(':
+                            case '\'':
+                            case '"':   // various non-filename characters
+                                print = true; // mean it's not a filename
+                                goto default;
+
+                            default:
+                                linebuf.writeByte(c);
                                 break;
-                            }
                         }
                     }
-                    printf("%.*s", cast(int)data.length, data.ptr);
                 }
 
                 // Convert command to wchar
@@ -1103,7 +1125,10 @@ public int runPreprocessor(const(char)[] cpp, const(char)[] filename, const(char
                 auto szCommand = toWStringz(buf.peekChars()[0 .. buf.length], smbuf);
 
                 int exitCode = runProcessCollectStdout(szCommand.ptr, buffer[], &sink);
-                printf("\n");
+
+                if (linebuf.length && print)  // anything leftover from stdout collection
+                    printf("%s\n", defines.peekChars());
+
                 return exitCode;
             }
             else
diff --git a/test/compilable/testdefines.c b/test/compilable/imports/defines.c
similarity index 59%
rename from test/compilable/testdefines.c
rename to test/compilable/imports/defines.c
index 0e54447e758a..f5bd6971375d 100644
--- a/test/compilable/testdefines.c
+++ b/test/compilable/imports/defines.c
@@ -1,3 +1,3 @@
-// DISABLED: win64 win32mscoff
+/* */
 #define GHI 3
 _Static_assert(GHI == 3, "1");
diff --git a/test/compilable/testdefines.d b/test/compilable/testdefines.d
new file mode 100644
index 000000000000..fad20002f989
--- /dev/null
+++ b/test/compilable/testdefines.d
@@ -0,0 +1,4 @@
+// EXTRA_FILES: imports/defines.c
+import imports.defines;
+
+static assert(GHI == 3);