[pushed] c++: "" #pragma at BOF [PR108504]

[pushed] c++: "" #pragma at BOF [PR108504]

[Jason Merrill]

Tested x86_64-pc-linux-gnu, applying to trunk.

-- 8< --

Since r11-2095 we pass flags to cp_lexer_get_preprocessor_token, and
cp_lexer_new_main passes C_LEX_STRING_NO_JOIN when lexing most of the
translation unit, but doesn't do that for the very first token; as a
result, if the first token is a string literal, we try to join strings and
get confused if that encounters a pragma.

	PR c++/108504

gcc/cp/ChangeLog:

	* parser.cc (cp_lexer_new_main): Pass C_LEX_STRING_NO_JOIN for first
	token, too.

gcc/testsuite/ChangeLog:

	* g++.dg/ext/pragma1.C: New test.
---
 gcc/cp/parser.cc                   | 2 +-
 gcc/testsuite/g++.dg/ext/pragma1.C | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/ext/pragma1.C

diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index b38c22e9a3d..07ec0e14491 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -705,7 +705,7 @@ cp_lexer_new_main (void)
   /* It's possible that parsing the first pragma will load a PCH file,
      which is a GC collection point.  So we have to do that before
      allocating any memory.  */
-  cp_lexer_get_preprocessor_token (0, &token);
+  cp_lexer_get_preprocessor_token (C_LEX_STRING_NO_JOIN, &token);
   cp_parser_initial_pragma (&token);
   c_common_no_more_pch ();
 
diff --git a/gcc/testsuite/g++.dg/ext/pragma1.C b/gcc/testsuite/g++.dg/ext/pragma1.C
new file mode 100644
index 00000000000..bb258dac9a7
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/pragma1.C
@@ -0,0 +1,4 @@
+// PR c++/108504
+
+"1"				// { dg-error "" }
+#pragma GCC diagnostic push

base-commit: 049a52909075117f5112971cc83952af2a818bc1
-- 
2.31.1