Run parse_util_detect_errors on -c commands

This didn't do all the syntax checks, so something like

    fish -c 'echo foo; and $status'

complained of a missing command `0` (i.e. $status), and

    fish -c 'echo foo | exec grep'

hit an assert!

So we do what read_ni does, parse each command into an ast, run
parse_util_detect_errors on it if it worked and then eval the ast.

It is possible to do this neater by modifying parser::eval, but I
can't find where.

src/fish.cpp

@@ -51,6 +51,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
 #include "intern.h"
 #include "io.h"
 #include "parser.h"
+#include "parse_util.h"
 #include "path.h"
 #include "proc.h"
 #include "reader.h"
@@ -255,7 +256,25 @@ static int run_command_list(parser_t &parser, std::vector<std::string> *cmds,
                             const io_chain_t &io) {
     for (const auto &cmd : *cmds) {
         wcstring cmd_wcs = str2wcstring(cmd);
-        parser.eval(cmd_wcs, io);
+        // Parse into an ast and detect errors.
+        parse_error_list_t errors;
+        auto ast = ast::ast_t::parse(cmd_wcs, parse_flag_none, &errors);
+        bool errored = ast.errored();
+        if (!errored) {
+            errored = parse_util_detect_errors(ast, cmd_wcs, &errors);
+        }
+        if (!errored) {
+            // Construct a parsed source ref.
+            // Be careful to transfer ownership, this could be a very large string.
+            parsed_source_ref_t ps = std::make_shared<parsed_source_t>(std::move(cmd_wcs), std::move(ast));
+            parser.eval(ps, io);
+        } else {
+            wcstring sb;
+            parser.get_backtrace(cmd_wcs, errors, sb);
+            std::fwprintf(stderr, L"%ls", sb.c_str());
+            // Note: We do not return here because that's how it historically worked.
+            // return 1;
+        }
     }
 
     return 0;

tests/checks/expansion.fish

@@ -306,12 +306,10 @@ $fish -c 'echo {'
 #CHECKERR: fish: Unexpected end of string, incomplete parameter expansion
 #CHECKERR: echo {
 #CHECKERR: ^
-#CHECKERR: 
 $fish -c 'echo {}}'
 #CHECKERR: fish: Unexpected '}' for unopened brace expansion
 #CHECKERR: echo {}}
 #CHECKERR: ^
-#CHECKERR: 
 $fish -c 'command (asd)'
 #CHECKERR: fish: Command substitutions not allowed
 #CHECKERR: command (asd)

tests/checks/invocation.fish

@@ -78,3 +78,15 @@ and echo matched
 string match -rq "echo thisshouldneverbeintheconfig" < $tmp/full.prof
 and echo matched
 # CHECK: matched
+
+$fish --no-config -c 'echo notprinted; echo foo | exec true; echo banana'
+# CHECKERR: fish: The 'exec' command can not be used in a pipeline
+# CHECKERR: echo notprinted; echo foo | exec true; echo banana
+# CHECKERR: ^
+
+# Running multiple command lists continues even if one has a syntax error.
+$fish --no-config -c 'echo $$ oh no syntax error' -c 'echo this works'
+# CHECK: this works
+# CHECKERR: fish: $$ is not the pid. In fish, please use $fish_pid.
+# CHECKERR: echo $$ oh no syntax error
+# CHECKERR: ^