Merge pull request #35309 from JuliaLang/jb/fix35305

fix #35305, need escaping when printing string macro calls

Author: JeffBezanson

base/show.jl

@@ -1500,11 +1500,13 @@ function show_unquoted(io::IO, ex::Expr, indent::Int, prec::Int, quote_level::In
                is_core_macro(args[1], "@big_str")
             print(io, args[3])
         # x"y" and x"y"z
-        elseif isa(args[1], Symbol) &&
+        elseif isa(args[1], Symbol) && nargs >= 3 && isa(args[3], String) &&
                startswith(string(args[1]::Symbol), "@") &&
                endswith(string(args[1]::Symbol), "_str")
             s = string(args[1]::Symbol)
-            print(io, s[2:prevind(s,end,4)], "\"", args[3], "\"")
+            print(io, s[2:prevind(s,end,4)], "\"")
+            escape_raw_string(io, args[3])
+            print(io, "\"")
             if nargs == 4
                 print(io, args[4])
             end

base/strings/io.jl

@@ -523,6 +523,55 @@ julia> println(raw"\\\\x \\\\\\"")
 """
 macro raw_str(s); s; end
 
+"""
+    escape_raw_string(s::AbstractString)
+    escape_raw_string(io, s::AbstractString)
+
+Escape a string in the manner used for parsing raw string literals.
+For each double-quote (`"`) character in input string `s`, this
+function counts the number _n_ of preceeding backslash (`\\`) characters,
+and then increases there the number of backslashes from _n_ to 2_n_+1
+(even for _n_ = 0). It also doubles a sequence of backslashes at the end
+of the string.
+
+This escaping convention is used in raw strings and other non-standard
+string literals. (It also happens to be the escaping convention
+expected by the Microsoft C/C++ compiler runtime when it parses a
+command-line string into the argv[] array.)
+
+See also: [`escape_string`](@ref)
+"""
+function escape_raw_string(io, str::AbstractString)
+    escapes = 0
+    for c in str
+        if c == '\\'
+            escapes += 1
+        else
+            if c == '"'
+                # if one or more backslashes are followed by
+                # a double quote then escape all backslashes
+                # and the double quote
+                escapes = escapes * 2 + 1
+            end
+            while escapes > 0
+                write(io, '\\')
+                escapes -= 1
+            end
+            escapes = 0
+            write(io, c)
+        end
+    end
+    # also escape any trailing backslashes,
+    # so they do not affect the closing quote
+    while escapes > 0
+        write(io, '\\')
+        write(io, '\\')
+        escapes -= 1
+    end
+end
+escape_raw_string(str::AbstractString) = sprint(escape_raw_string, str;
+                                                sizehint = lastindex(str) + 2)
+
 ## multiline strings ##
 
 """

test/show.jl

@@ -1133,6 +1133,9 @@ z856739 = [:a, :b]
 @test sprint(show, Meta.parse("a\"b\"c")) == ":(a\"b\"c)"
 @test sprint(show, Meta.parse("aa\"b\"")) == ":(aa\"b\")"
 @test sprint(show, Meta.parse("a\"b\"cc")) == ":(a\"b\"cc)"
+@test sprint(show, Meta.parse("a\"\"\"issue \"35305\" \"\"\"")) == ":(a\"issue \\\"35305\\\" \")"
+@test sprint(show, Meta.parse("a\"\$\"")) == ":(a\"\$\")"
+@test sprint(show, Meta.parse("a\"\\b\"")) == ":(a\"\\b\")"
 # 11111111111111111111, 0xfffffffffffffffff, 1111...many digits...
 @test sprint(show, Meta.parse("11111111111111111111")) == ":(11111111111111111111)"
 # @test_repr "Base.@int128_str \"11111111111111111111\""

test/strings/io.jl

@@ -148,6 +148,7 @@
         @test "aaa \\g \n" == unescape_string(str, ['g'])
         @test "aaa \\g \\n" == unescape_string(str, ['g', 'n'])
     end
+    @test Base.escape_raw_string(raw"\"\\\"\\-\\") == "\\\"\\\\\\\"\\\\-\\\\"
 end
 @testset "join()" begin
     @test join([]) == join([],",") == ""