Fix clc device selection on multi-device platform

If a platform reports multiple devices, they will all have the same name
and --device selection will be ambiguous.

This adds a --device-idx cmd-line option to directly select by index.

Author: dlopr

modules/cargo/include/cargo/argument_parser.h

@@ -219,7 +219,7 @@ class argument {
     cargo::array_view<cargo::string_view> Choices;
   };
   union {
-    bool *Bool;
+    bool *Bool = {};
     cargo::string_view *Value;
     ChoiceT Choice;
     cargo::small_vector<cargo::string_view, 4> *Values;

source/cl/tools/clc/clc.cpp

@@ -25,6 +25,7 @@
 
 #include <algorithm>
 #include <array>
+#include <charconv>
 #include <cstdio>
 #include <cstdlib>
 #include <fstream>
@@ -152,6 +153,7 @@ driver::driver()
       dry_run(false),
       input_file(),
       output_file(""),
+      device_idx(0),
       device_name_substring(""),
       cl_build_args(),
       strip_binary_header(false),
@@ -185,6 +187,9 @@ optional arguments:
                         output file path, defaults to the name of the last
                         input file "<input>.bin" if present, or "-" otherwise
                         to write to standard output
+  --device-idx index
+                        the index (1..N) of the device to select. Takes precedence
+                        over --device
   -d name, --device name
                         a substring of the device name to select, choose from:%s
   --list-devices        print the list of available devices and exit
@@ -275,6 +280,18 @@ result driver::parseArguments(int argc, char **argv) {
   CHECK(parser.add_argument({"-o", output_file}));
   CHECK(parser.add_argument({"--output", output_file}));
 
+  CHECK(parser.add_argument({
+    "--device-idx",
+    [](auto&&...){ return parse::INCOMPLETE; },
+    [this](cargo::string_view str_value){
+      auto [ptr, ec] = std::from_chars(str_value.begin(), str_value.end(), device_idx);
+      if ((ptr != str_value.end()) || (device_idx == 0)) {
+        return parse::INVALID;
+      }
+      return parse::COMPLETE;
+    },
+  }));
+
   CHECK(parser.add_argument({"-d", device_name_substring}));
   CHECK(parser.add_argument({"--device", device_name_substring}));
 
@@ -743,38 +760,51 @@ result driver::findDevice() {
     return result::failure;
   }
 
-  if (compilers.size() > 1 && device_name_substring.empty()) {
-    (void)std::fprintf(stderr,
-                       "error: Multiple devices available, please choose one "
-                       "(--device NAME):\n");
-    printMuxCompilers(compilers);
-    return result::failure;
-  }
-
-  bool found = false;
-  for (auto compiler : compilers) {
-    bool matches = true;
-    if (!device_name_substring.empty()) {
-      matches &= matchSubstring(compiler->device_info->device_name,
-                                device_name_substring);
-    }
-    if (matches) {
-      if (found) {
-        (void)std::fprintf(
-            stderr, "error: Device selection ambiguous, available devices:\n");
+  if (device_idx != 0) {
+    if (device_idx > compilers.size()) {
+        (void)std::fprintf(stderr,
+                          "error: Invalid device selection; out of bounds. "
+                          "Available devices:\n");
         printMuxCompilers(compilers);
         return result::failure;
+    }
+
+    compiler_info = compilers[device_idx - 1];
+
+  } else {
+    if (compilers.size() > 1 && device_name_substring.empty()) {
+      (void)std::fprintf(stderr,
+                        "error: Multiple devices available, please choose one "
+                        "(--device NAME | --device-idx INDEX):\n");
+      printMuxCompilers(compilers);
+      return result::failure;
+    }
+
+    bool found = false;
+    for (auto compiler : compilers) {
+      bool matches = true;
+      if (!device_name_substring.empty()) {
+        matches &= matchSubstring(compiler->device_info->device_name,
+                                  device_name_substring);
+      }
+      if (matches) {
+        if (found) {
+          (void)std::fprintf(
+              stderr, "error: Device selection ambiguous, available devices:\n");
+          printMuxCompilers(compilers);
+          return result::failure;
+        }
+        found = true;
+        compiler_info = compiler;
       }
-      found = true;
-      compiler_info = compiler;
     }
-  }
-  if (!found) {
-    (void)std::fprintf(
-        stderr,
-        "error: No device matched the given substring, available devices:\n");
-    printMuxCompilers(compilers);
-    return result::failure;
+    if (!found) {
+      (void)std::fprintf(
+          stderr,
+          "error: No device matched the given substring, available devices:\n");
+      printMuxCompilers(compilers);
+      return result::failure;
+    }
   }
 
   if (verbose) {

source/cl/tools/clc/clc.h

@@ -66,6 +66,8 @@ class driver {
   std::string input_file;
   /// @brief Path to the output file or `"-"` for `stdout`.
   cargo::string_view output_file;
+  /// @brief Device index to select from multiple devices. Takes precedence over device name.
+  size_t device_idx;
   /// @brief Device name substring to select from multiple devices.
   cargo::string_view device_name_substring;
   /// @brief List of compile options passed to `clBuildProgram`.