Treat block in ifelse conditional as Expr wart

Instead of baking this into the parser output, we treat this extra block
as an Expr-specific oddity and add it during Expr conversion.

Author: c42f

README.md

@@ -127,7 +127,7 @@ tree", but that term has also been used for the parse tree of the full formal
 grammar for a language including any grammar hacks required to solve
 ambiguities, etc. So we avoid this term.)
 
-`JuliaSyntax` uses use a mostly recursive descent parser which closely
+`JuliaSyntax` uses a mostly recursive descent parser which closely
 follows the high level structure of the flisp reference parser. This makes the
 code familiar and reduces porting bugs. It also gives a lot of flexibility for
 designing the diagnostics, tree data structures, compatibility with different

src/expr.jl

@@ -144,6 +144,9 @@ function _to_expr(node::SyntaxNode, iteration_spec=false)
                 args[2] = Expr(:block, loc, args[2])
             end
         end
+    elseif headsym == :elseif
+        # Compat wart: add a block for the elseif conditional
+        args[1] = Expr(:block, args[1])
     elseif headsym == :(->)
         if Meta.isexpr(args[2], :block)
             pushfirst!(args[2].args, loc)

src/parser.jl

@@ -1852,7 +1852,7 @@ end
 
 # Parse if-elseif-else-end expressions
 #
-# if a xx elseif b yy else zz end   ==>  (if a (block xx) (elseif (block b) (block yy) (block zz)))
+# if a xx elseif b yy else zz end   ==>  (if a (block xx) (elseif b (block yy) (block zz)))
 function parse_if_elseif(ps, is_elseif=false, is_elseif_whitespace_err=false)
     mark = position(ps)
     word = peek(ps)
@@ -1872,23 +1872,19 @@ function parse_if_elseif(ps, is_elseif=false, is_elseif_whitespace_err=false)
         # if a xx end   ==>  (if a (block xx))
         parse_cond(ps)
     end
-    if is_elseif
-        # Wart: `elseif` condition is in a block but not `if` condition
-        emit(ps, cond_mark, K"block")
-    end
     # if a \n\n xx \n\n end   ==>  (if a (block xx))
     parse_block(ps)
     bump_trivia(ps)
     k = peek(ps)
     if k == K"elseif"
-        # if a xx elseif b yy end   ==>  (if a (block xx) (elseif (block b) (block yy)))
+        # if a xx elseif b yy end   ==>  (if a (block xx) (elseif b (block yy)))
         parse_if_elseif(ps, true)
     elseif k == K"else"
         emark = position(ps)
         bump(ps, TRIVIA_FLAG)
         if peek(ps) == K"if"
             # Recovery: User wrote `else if` by mistake ?
-            # if a xx else if b yy end  ==>  (if a (block xx) (error-t) (elseif (block b) (block yy)))
+            # if a xx else if b yy end  ==>  (if a (block xx) (error-t) (elseif b (block yy)))
             bump(ps, TRIVIA_FLAG)
             emit(ps, emark, K"error", TRIVIA_FLAG,
                  error="use `elseif` instead of `else if`")

test/syntax_tree.jl renamed to test/expr.jl

@@ -390,14 +390,14 @@ tests = [
         "export (\$f)"  =>  "(export (\$ f))"
     ],
     JuliaSyntax.parse_if_elseif => [
-        "if a xx elseif b yy else zz end" => "(if a (block xx) (elseif (block b) (block yy) (block zz)))"
+        "if a xx elseif b yy else zz end" => "(if a (block xx) (elseif b (block yy) (block zz)))"
         "if end"        =>  "(if (error) (block))"
         "if \n end"     =>  "(if (error) (block))"
         "if a end"      =>  "(if a (block))"
         "if a xx end"   =>  "(if a (block xx))"
         "if a \n\n xx \n\n end"   =>  "(if a (block xx))"
-        "if a xx elseif b yy end"   =>  "(if a (block xx) (elseif (block b) (block yy)))"
-        "if a xx else if b yy end"  =>  "(if a (block xx) (error-t) (elseif (block b) (block yy)))"
+        "if a xx elseif b yy end"   =>  "(if a (block xx) (elseif b (block yy)))"
+        "if a xx else if b yy end"  =>  "(if a (block xx) (error-t) (elseif b (block yy)))"
         "if a xx else yy end"   =>  "(if a (block xx) (block yy))"
     ],
     JuliaSyntax.parse_const_local_global => [

test/parser.jl

@@ -18,7 +18,7 @@ include("test_utils.jl")
 include("parse_stream.jl")
 include("parser.jl")
 include("parser_api.jl")
-include("syntax_tree.jl")
+include("expr.jl")
 @testset "Parsing values from strings" begin
     include("value_parsing.jl")
 end