Ast dump ignore wmo (#20596)

* Ignore -wmo when passing -dump-ast

* Cleanup on driver diagnostics

* Remove the FIXME.

* Add support for ignoring `-index-file`

* Revert unrelated formatting changes

* Revert back to only ignoring `-wmo`

Ignoring both `-wmo` and `-index-file` will be harder than just `-wmo`. This is because when calling the compiler and passing `-index-file` after `-dump-ast`, the option gets un-ignored by `Driver::buildOutputInfo`. Therefore, we will just ignore `-wmo` for now.

* Add tests, inspired by `Driver/batch_mode_with_WMO_or_index.swift`

Author: vinivendra

include/swift/AST/DiagnosticsDriver.def

@@ -166,6 +166,9 @@ WARNING(warn_opt_remark_disabled, none,
 WARNING(warn_ignoring_batch_mode,none,
 "ignoring '-enable-batch-mode' because '%0' was also specified", (StringRef))
 
+WARNING(warn_ignoring_wmo, none,
+        "ignoring '-wmo' because '-dump-ast' was also specified", ())
+
 WARNING(warn_ignoring_source_range_dependencies,none,
 "ignoring '-enable-source-range-dependencies' because '%0' was also specified", (StringRef))
 

lib/Driver/Driver.cpp

@@ -1764,6 +1764,17 @@ Driver::computeCompilerMode(const DerivedArgList &Args,
   const Arg *ArgRequiringSinglePrimaryCompile =
       Args.getLastArg(options::OPT_enable_source_range_dependencies);
 
+  // AST dump doesn't work with `-wmo`. Since it's not common to want to dump
+  // the AST, we assume that's the priority and ignore `-wmo`, but we warn the
+  // user about this decision.
+  // FIXME: AST dump also doesn't work with `-index-file`, but that fix is a bit
+  // more complicated than this.
+  if (Args.hasArg(options::OPT_whole_module_optimization) &&
+      Args.hasArg(options::OPT_dump_ast)) {
+    Diags.diagnose(SourceLoc(), diag::warn_ignoring_wmo);
+    return OutputInfo::Mode::StandardCompile;
+  }
+
   // Override batch mode if given -wmo or -index-file.
   if (ArgRequiringSingleCompile) {
     if (BatchModeOut) {

lib/FrontendTool/FrontendTool.cpp

@@ -894,10 +894,6 @@ static SourceFile *getPrimaryOrMainSourceFile(CompilerInvocation &Invocation,
 /// files were specified, use them; otherwise, dump the AST to stdout.
 static void dumpAST(CompilerInvocation &Invocation,
                     CompilerInstance &Instance) {
-  // FIXME: WMO doesn't use the notion of primary files, so this doesn't do the
-  // right thing. Perhaps it'd be best to ignore WMO when dumping the AST, just
-  // like WMO ignores `-incremental`.
-
   auto primaryFiles = Instance.getPrimarySourceFiles();
   if (!primaryFiles.empty()) {
     for (SourceFile *sourceFile: primaryFiles) {

test/Driver/ast_dump_with_WMO.swift

@@ -0,0 +1,38 @@
+// RUN: %empty-directory(%t)
+
+
+// Check that -wmo is ignored when -dump-ast is present and that the AST gets
+// dumped to stdout, no matter the order of the options
+
+// RUN: %swiftc_driver -whole-module-optimization -dump-ast -module-name=main %S/../Inputs/empty.swift -### 2>%t/stderr_WMO_dump | %FileCheck -check-prefix CHECK-STDOUT %s
+// RUN: %swiftc_driver -dump-ast -whole-module-optimization -module-name=main %S/../Inputs/empty.swift -### 2>%t/stderr_dump_WMO | %FileCheck -check-prefix CHECK-STDOUT %s
+// RUN: %FileCheck -check-prefix CHECK-WMO %s <%t/stderr_WMO_dump
+// RUN: %FileCheck -check-prefix CHECK-WMO %s <%t/stderr_dump_WMO
+
+
+// Check that ignoring -wmo doesn't affect the output file paths for the AST
+// dumps
+
+// RUN: cd %t
+// RUN: echo ' ' > a.swift
+// RUN: echo ' ' > main.swift
+// RUN: echo '{ "a.swift": { "ast-dump": "a.ast" }, "main.swift": { "ast-dump": "main.ast" }}' > outputFileMap.json
+
+// RUN: %swiftc_driver -whole-module-optimization -dump-ast -module-name=main -output-file-map=outputFileMap.json main.swift a.swift -### 2>%t/stderr_WMO_OFM | %FileCheck -check-prefix CHECK-OFM %s
+// RUN: %FileCheck -check-prefix CHECK-WMO %s <%t/stderr_WMO_OFM
+
+
+
+// CHECK-WMO: warning: ignoring '-wmo' because '-dump-ast' was also specified
+
+// CHECK-STDOUT-NOT: -whole-module-optimization
+// CHECK-STDOUT-NOT: -wmo
+// CHECK-STDOUT: -dump-ast
+// CHECK-STDOUT: -o -
+
+// CHECK-OFM-NOT: -whole-module-optimization
+// CHECK-OFM-NOT: -wmo
+// CHECK-OFM: -dump-ast
+// CHECK-OFM-SAME: -o main.ast
+// CHECK-OFM-NEXT: -dump-ast
+// CHECK-OFM-SAME: -o a.ast