[AST] Introduce a minimal SubstitutionMap dump for use inside expressions.

Within a dump of a DeclRef (or, more likely, a larger entity that includes one),
the full multiline details of a substitution map are likely to not be hugely
relevant, and just get in the way of understanding the interesting parts of the
dump. Thus, this is a variant that is a single line and just includes the
substitutions; the conformances (or, at least, the protocols involved) can be
inferred from the generic signature combined with those substitutions.

The style is controlled via a enum rather than a boolean, to avoid problems with
trying to pass an indent like `map->dump(out, indent)`, where the integer indent
coerces to a bool, rather than error.

Fixes rdar://problem/40074968.

Author: huonw

include/swift/AST/SubstitutionMap.h

@@ -218,8 +218,12 @@ class SubstitutionMap {
   /// Verify that this substitution map is valid.
   void verify() const;
 
+  /// Whether to dump the full substitution map, or just a minimal useful subset
+  /// (on a single line).
+  enum class DumpStyle { Minimal, Full };
   /// Dump the contents of this substitution map for debugging purposes.
-  void dump(llvm::raw_ostream &out, unsigned indent = 0) const;
+  void dump(llvm::raw_ostream &out, DumpStyle style = DumpStyle::Full,
+            unsigned indent = 0) const;
 
   LLVM_ATTRIBUTE_DEPRECATED(void dump() const, "only for use in the debugger");
 

lib/AST/ASTDumper.cpp

@@ -23,6 +23,7 @@
 #include "swift/AST/ParameterList.h"
 #include "swift/AST/ProtocolConformance.h"
 #include "swift/AST/TypeVisitor.h"
+#include "swift/Basic/Defer.h"
 #include "swift/Basic/QuotedString.h"
 #include "swift/Basic/STLExtras.h"
 #include "llvm/ADT/APFloat.h"
@@ -2905,7 +2906,8 @@ static void dumpProtocolConformanceRec(
       break;
 
     out << '\n';
-    conf->getSubstitutionMap().dump(out, indent + 2);
+    conf->getSubstitutionMap().dump(out, SubstitutionMap::DumpStyle::Full,
+                                    indent + 2);
     out << '\n';
     for (auto subReq : conf->getConditionalRequirements()) {
       out.indent(indent + 2);
@@ -2939,27 +2941,33 @@ void ProtocolConformance::dump(llvm::raw_ostream &out, unsigned indent) const {
   dumpProtocolConformanceRec(this, out, indent, visited);
 }
 
-void SubstitutionMap::dump(llvm::raw_ostream &out, unsigned indent) const {
+void SubstitutionMap::dump(llvm::raw_ostream &out,
+                           SubstitutionMap::DumpStyle style,
+                           unsigned indent) const {
   auto *genericSig = getGenericSignature();
   out.indent(indent);
 
   auto printParen = [&](char p) {
     PrintWithColorRAII(out, ParenthesisColor) << p;
   };
   printParen('(');
+  SWIFT_DEFER { printParen(')'); };
   out << "substitution_map generic_signature=";
   if (genericSig == nullptr) {
     out << "<nullptr>";
-    printParen(')');
     return;
   }
 
   genericSig->print(out);
   auto genericParams = genericSig->getGenericParams();
   auto replacementTypes = getReplacementTypesBuffer();
   for (unsigned i : indices(genericParams)) {
-    out << "\n";
-    out.indent(indent + 2);
+    if (style == SubstitutionMap::DumpStyle::Minimal) {
+      out << " ";
+    } else {
+      out << "\n";
+      out.indent(indent + 2);
+    }
     printParen('(');
     out << "substitution ";
     genericParams[i]->print(out);
@@ -2970,6 +2978,10 @@ void SubstitutionMap::dump(llvm::raw_ostream &out, unsigned indent) const {
       out << "<<unresolved concrete type>>";
     printParen(')');
   }
+  // A minimal dump doesn't need the details about the conformances, a lot of
+  // that info can be inferred from the signature.
+  if (style == SubstitutionMap::DumpStyle::Minimal)
+    return;
 
   // We only really need to print a conformance once across this whole map.
   llvm::SmallPtrSet<const ProtocolConformance *, 8> visited;

lib/AST/ConcreteDeclRef.cpp

@@ -56,7 +56,7 @@ void ConcreteDeclRef::dump(raw_ostream &os) {
   // If specialized, dump the substitutions.
   if (isSpecialized()) {
     os << " [with ";
-    getSubstitutions().dump(os);
+    getSubstitutions().dump(os, SubstitutionMap::DumpStyle::Minimal);
     os << ']';
   }
 }

test/Driver/dump-parse.swift

@@ -54,3 +54,10 @@ enum TrailingSemi {
     return y;
   };
 };
+
+// The substitution map for a declref should be relatively unobtrustive.
+// CHECK-AST-LABEL:   (func_decl "generic(_:)" <T : Hashable> interface type='<T where T : Hashable> (T) -> ()' access=internal captures=(<generic> )
+func generic<T: Hashable>(_: T) {}
+// CHECK-AST:       (pattern_binding_decl
+// CHECK-AST:         (declref_expr type='(Int) -> ()' location={{.*}} range={{.*}} decl=main.(file).generic@{{.*}} [with (substitution_map generic_signature=<T where T : Hashable> (substitution T -> Int))] function_ref=unapplied))
+let _: (Int) -> () = generic