syntax: use fewer newlines in heredocs with minify

Given the shell

  a=$(
    cat <<EOF
    hello
  EOF
  )

We would format it into

  a=$(cat \
  <<EOF)
    hello
  EOF

First, this makes bash unhappy, as it wants to find the closing EOF
before we close the command substitution. Teach rightParen to use a
newline if there are any pending heredocs, even if we're minifying.

Second, the escaped newline before the redirect is unnecessary.

Now, we format the shell into

  a=$(cat <<EOF
    hello
  EOF
  )

Thanks to Andrey Kaipov for the report and test cases.

Fixes #923.

syntax/printer.go

@@ -308,7 +308,7 @@ func (p *Printer) spacePad(pos Pos) {
 // wantsNewline reports whether we want to print at least one newline before
 // printing a node at a given position. A zero position can be given to simply
 // tell if we want a newline following what's just been printed.
-func (p *Printer) wantsNewline(pos Pos) bool {
+func (p *Printer) wantsNewline(pos Pos, escapingNewline bool) bool {
 	if p.mustNewline {
 		// We must have a newline here.
 		return true
@@ -319,7 +319,10 @@ func (p *Printer) wantsNewline(pos Pos) bool {
 		// as that might move them further down to the wrong place.
 		return false
 	}
-	// THe newline is optional, and we want it via either wantNewline or via
+	if escapingNewline && p.minify {
+		return false
+	}
+	// The newline is optional, and we want it via either wantNewline or via
 	// the position's line.
 	return p.wantNewline || pos.Line() > p.line
 }
@@ -351,7 +354,7 @@ func (p *Printer) spacedToken(s string, pos Pos) {
 }
 
 func (p *Printer) semiOrNewl(s string, pos Pos) {
-	if p.wantsNewline(Pos{}) {
+	if p.wantsNewline(Pos{}, false) {
 		p.newline(pos)
 		p.indent()
 	} else {
@@ -509,7 +512,7 @@ func (p *Printer) newlines(pos Pos) {
 		p.firstLine = false
 		return // no empty lines at the top
 	}
-	if !p.wantsNewline(pos) {
+	if !p.wantsNewline(pos, false) {
 		return
 	}
 	p.flushHeredocs()
@@ -527,15 +530,15 @@ func (p *Printer) newlines(pos Pos) {
 }
 
 func (p *Printer) rightParen(pos Pos) {
-	if !p.minify {
+	if len(p.pendingHdocs) > 0 || !p.minify {
 		p.newlines(pos)
 	}
 	p.WriteByte(')')
 	p.wantSpace = spaceRequired
 }
 
 func (p *Printer) semiRsrv(s string, pos Pos) {
-	if p.wantsNewline(pos) {
+	if p.wantsNewline(pos, false) {
 		p.newlines(pos)
 	} else {
 		if !p.wroteSemi {
@@ -955,7 +958,7 @@ func (p *Printer) casePatternJoin(pats []*Word) {
 		if i > 0 {
 			p.spacedToken("|", Pos{})
 		}
-		if p.wantsNewline(w.Pos()) {
+		if p.wantsNewline(w.Pos(), true) {
 			if !anyNewline {
 				p.incLevel()
 				anyNewline = true
@@ -1015,7 +1018,7 @@ func (p *Printer) stmt(s *Stmt) {
 	}
 	p.incLevel()
 	for _, r := range s.Redirs[startRedirs:] {
-		if p.wantsNewline(r.OpPos) {
+		if p.wantsNewline(r.OpPos, true) {
 			p.bslashNewl()
 		}
 		if p.wantSpace == spaceRequired {
@@ -1413,7 +1416,7 @@ func (p *Printer) nestedStmts(stmts []*Stmt, last []Comment, closing Pos) {
 func (p *Printer) assigns(assigns []*Assign) {
 	p.incLevel()
 	for _, a := range assigns {
-		if p.wantsNewline(a.Pos()) {
+		if p.wantsNewline(a.Pos(), true) {
 			p.bslashNewl()
 		} else {
 			p.spacePad(a.Pos())

syntax/printer_test.go

@@ -1068,6 +1068,15 @@ func TestPrintMinify(t *testing.T) {
 		},
 		samePrint("foo >bar 2>baz <etc"),
 		samePrint("<<-EOF\n$(a|b)\nEOF"),
+		{
+			"a=$(\n\tcat <<'EOF'\n  hello\nEOF\n)",
+			"a=$(cat <<'EOF'\n  hello\nEOF\n)",
+		},
+		{
+			"(\n\tcat <<EOF\n hello\nEOF\n)",
+			"(cat <<EOF\n hello\nEOF\n)",
+		},
+		samePrint("diff -y <(cat <<EOF\n1\n2\n3\nEOF\n) <(cat <<EOF\n1\n4\n3\nEOF\n)"),
 	}
 	parser := NewParser(KeepComments(true))
 	printer := NewPrinter(Minify(true))
@@ -1161,8 +1170,8 @@ func TestPrintOptionsNotBroken(t *testing.T) {
 		{"SingleLine", []PrinterOption{SingleLine(true)}},
 	} {
 		printer := NewPrinter(opts.list...)
-		for i, tc := range append(fileTests, fileTestsNoPrint...) {
-			t.Run(fmt.Sprintf("File%s%03d", opts.name, i), func(t *testing.T) {
+		for _, tc := range append(fileTests, fileTestsNoPrint...) {
+			t.Run("File"+opts.name, func(t *testing.T) {
 				parser := parserPosix
 				if tc.Bats != nil {
 					parser = parserBats
@@ -1189,8 +1198,8 @@ func TestPrintOptionsNotBroken(t *testing.T) {
 				}
 			})
 		}
-		for i, tc := range printTests {
-			t.Run(fmt.Sprintf("Print%s%03d", opts.name, i), func(t *testing.T) {
+		for _, tc := range printTests {
+			t.Run("Print"+opts.name, func(t *testing.T) {
 				prog, err := parserBash.Parse(strings.NewReader(tc.in), "")
 				if err != nil {
 					t.Fatal(err)