Implement -stdin.

src/ddmd/globals.d

@@ -122,6 +122,7 @@ struct Param
     bool enforcePropertySyntax;
     bool betterC;           // be a "better C" compiler; no dependency on D runtime
     bool addMain;           // add a default main() function
+    bool readStdin;         // read source code from standard input
     bool allInst;           // generate code for all template instantiations
     bool check10378;        // check for issues transitioning to 10738
     bool bug10378;          // use pre- https://issues.dlang.org/show_bug.cgi?id=10378 search strategy
@@ -221,6 +222,7 @@ struct Global
     const(char)* copyright;
     const(char)* written;
     const(char)* main_d;            // dummy filename for dummy main()
+    const(char)* stdin_d;           // dummy filename for reading from stdin
     Array!(const(char)*)* path;     // Array of char*'s which form the import lookup path
     Array!(const(char)*)* filePath; // Array of char*'s which form the file import lookup path
 
@@ -339,6 +341,7 @@ struct Global
         compiler.vendor = "Digital Mars D";
         stdmsg = stdout;
         main_d = "__main.d";
+        stdin_d = "__stdin.d";
         errorLimit = 20;
     }
 }

src/ddmd/globals.h

@@ -203,6 +203,7 @@ struct Global
     const char *copyright;
     const char *written;
     const char *main_d;         // dummy filename for dummy main()
+    const char *stdin_d;        // dummy filename for reading from stdin
     Array<const char *> *path;        // Array of char*'s which form the import lookup path
     Array<const char *> *filePath;    // Array of char*'s which form the file import lookup path
 

src/ddmd/mars.d

@@ -245,6 +245,52 @@ extern (C++) void genCmain(Scope* sc)
     rootHasMain = sc._module;
 }
 
+/**
+ * Copies data from a FILE* into a newly-allocated buffer.
+ *
+ * The buffer is always null-terminated.
+ */
+ubyte[] copyFile(FILE* fp)
+{
+    enum bufIncrement = 4096;
+    size_t pos = 0;
+    size_t sz = bufIncrement;
+
+    ubyte* buf = cast(ubyte*).malloc(sz + 1); // +1 for sentinel
+    if (buf is null)
+    {
+        error(Loc(), "out of memory");
+        fatal();
+    }
+
+    assert(sz > pos);
+    size_t rlen;
+    pos += rlen = fread(buf + pos, 1, sz - pos, fp);
+    while (!ferror(fp) && !feof(fp))
+    {
+        if (pos == sz)
+        {
+            sz += bufIncrement;
+            buf = cast(ubyte*).realloc(buf, sz + 1);
+            if (buf is null)
+            {
+                error(Loc(), "out of memory");
+                fatal();
+            }
+        }
+        assert(sz > pos);
+        pos += rlen = fread(buf + pos, 1, sz - pos, fp);
+    }
+    if (ferror(fp))
+    {
+        error(Loc(), "read error");
+        fatal();
+    }
+
+    assert(pos < sz+1);
+    buf[pos] = '\0';
+    return buf[0 .. pos+1];
+}
 
 /**
  * DMD's real entry point
@@ -434,6 +480,8 @@ private int tryMain(size_t argc, const(char)** argv)
             }
             else if (strcmp(p + 1, "shared") == 0)
                 global.params.dll = true;
+            else if (strcmp(p + 1, "stdin") == 0)
+                global.params.readStdin = true;
             else if (strcmp(p + 1, "dylib") == 0)
             {
                 static if (TARGET_OSX)
@@ -1081,7 +1129,7 @@ Language changes listed by -transition=id:
     {
         fatal();
     }
-    if (files.dim == 0)
+    if (files.dim == 0 && !global.params.readStdin)
     {
         usage();
         return EXIT_FAILURE;
@@ -1210,6 +1258,10 @@ Language changes listed by -transition=id:
     {
         files.push(cast(char*)global.main_d); // a dummy name, we never actually look up this file
     }
+    if (global.params.readStdin)
+    {
+        files.push(cast(char*)global.stdin_d); // a dummy name, we don't actually look it up
+    }
     // Create Modules
     Modules modules;
     modules.reserve(files.dim);
@@ -1343,6 +1395,22 @@ Language changes listed by -transition=id:
             }
         }
     }
+    if (global.params.readStdin)
+    {
+        for (size_t i = 0; 1; i++)
+        {
+            assert(i != modules.dim);
+            Module m = modules[i];
+            if (strcmp(m.srcfile.name.str, global.stdin_d) == 0)
+            {
+                /* Slow stdio-based read, because File.read doesn't work with
+                 * stdin. */
+                auto buf = copyFile(stdin);
+                m.srcfile.setbuffer(buf.ptr, buf.length);
+                break;
+            }
+        }
+    }
     enum ASYNCREAD = false;
     static if (ASYNCREAD)
     {