Go patch committed: Check for floating-point exponent overflow

[Ian Lance Taylor]

This patch to the Go frontend checks for floating-point exponent
overflow.  Previously we just ignored the error and carried on.  This
forces us to ignore some floating point constants in the mksysinfo and
mkrsysinfo shell scripts, and forces us to update a couple of tests.
Bootstrapped and ran Go testsuite on x86_64-pc-linux-gnu.  Committed
to mainline.

Ian
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91ea9a4f1e2a91f8e61a57399f08cf243eceea65
diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE
index 6567db167a2..40242cc6a3f 100644
--- a/gcc/go/gofrontend/MERGE
+++ b/gcc/go/gofrontend/MERGE
@@ -1,4 +1,4 @@
-526037336231593939a517b7c0b2892d413adb40
+1317de50147304a226b3ec5c4d81376470c358e5
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.
diff --git a/gcc/go/gofrontend/lex.cc b/gcc/go/gofrontend/lex.cc
index e71b8cddf65..0baf4e4e24b 100644
--- a/gcc/go/gofrontend/lex.cc
+++ b/gcc/go/gofrontend/lex.cc
@@ -1316,9 +1316,13 @@ Lex::gather_number()
 	}
     }
 
+  mpfr_clear_overflow();
   mpfr_t val;
   int r = mpfr_init_set_str(val, num.c_str(), base, MPFR_RNDN);
   go_assert(r == 0);
+  if (mpfr_overflow_p())
+    go_error_at(this->location(),
+		"floating-point exponent too large to represent");
 
   bool is_imaginary = *p == 'i';
   if (is_imaginary)
diff --git a/gcc/testsuite/go.test/test/fixedbugs/issue11326b.go b/gcc/testsuite/go.test/test/fixedbugs/issue11326b.go
index 8aba4d91215..b5f933bfea1 100644
--- a/gcc/testsuite/go.test/test/fixedbugs/issue11326b.go
+++ b/gcc/testsuite/go.test/test/fixedbugs/issue11326b.go
@@ -1,5 +1,9 @@
 // run
 
+// Does not work with gccgo, which uses a smaller (but still permitted)
+// exponent size.
+// +build !gccgo
+
 // Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
diff --git a/gcc/testsuite/go.test/test/fixedbugs/issue13471.go b/gcc/testsuite/go.test/test/fixedbugs/issue13471.go
index 9bfc8c3d2cf..9069412ffa6 100644
--- a/gcc/testsuite/go.test/test/fixedbugs/issue13471.go
+++ b/gcc/testsuite/go.test/test/fixedbugs/issue13471.go
@@ -9,17 +9,17 @@
 package main
 
 func main() {
-	const _ int64 = 1e646456992 // ERROR "integer too large|floating-point constant truncated to integer"
-	const _ int32 = 1e64645699  // ERROR "integer too large|floating-point constant truncated to integer"
-	const _ int16 = 1e6464569   // ERROR "integer too large|floating-point constant truncated to integer"
-	const _ int8 = 1e646456     // ERROR "integer too large|floating-point constant truncated to integer"
-	const _ int = 1e64645       // ERROR "integer too large|floating-point constant truncated to integer"
+	const _ int64 = 1e646456992 // ERROR "integer too large|floating-point constant truncated to integer|exponent too large"
+	const _ int32 = 1e64645699  // ERROR "integer too large|floating-point constant truncated to integer|exponent too large"
+	const _ int16 = 1e6464569   // ERROR "integer too large|floating-point constant truncated to integer|exponent too large"
+	const _ int8 = 1e646456     // ERROR "integer too large|floating-point constant truncated to integer|exponent too large"
+	const _ int = 1e64645       // ERROR "integer too large|floating-point constant truncated to integer|exponent too large"
 
-	const _ uint64 = 1e646456992 // ERROR "integer too large|floating-point constant truncated to integer"
-	const _ uint32 = 1e64645699  // ERROR "integer too large|floating-point constant truncated to integer"
-	const _ uint16 = 1e6464569   // ERROR "integer too large|floating-point constant truncated to integer"
-	const _ uint8 = 1e646456     // ERROR "integer too large|floating-point constant truncated to integer"
-	const _ uint = 1e64645       // ERROR "integer too large|floating-point constant truncated to integer"
+	const _ uint64 = 1e646456992 // ERROR "integer too large|floating-point constant truncated to integer|exponent too large"
+	const _ uint32 = 1e64645699  // ERROR "integer too large|floating-point constant truncated to integer|exponent too large"
+	const _ uint16 = 1e6464569   // ERROR "integer too large|floating-point constant truncated to integer|exponent too large"
+	const _ uint8 = 1e646456     // ERROR "integer too large|floating-point constant truncated to integer|exponent too large"
+	const _ uint = 1e64645       // ERROR "integer too large|floating-point constant truncated to integer|exponent too large"
 
-	const _ rune = 1e64645 // ERROR "integer too large|floating-point constant truncated to integer"
+	const _ rune = 1e64645 // ERROR "integer too large|floating-point constant truncated to integer|exponent too large"
 }
diff --git a/libgo/mkrsysinfo.sh b/libgo/mkrsysinfo.sh
index c28f0e5f1f6..e016ca4dc59 100755
--- a/libgo/mkrsysinfo.sh
+++ b/libgo/mkrsysinfo.sh
@@ -26,6 +26,7 @@ grep -v '^// ' gen-sysinfo.go | \
   grep -v '^type _*locale[_ ]' | \
   grep -v 'in6_addr' | \
   grep -v 'sockaddr_in6' | \
+  egrep -v '^const _*FLT(64|128)_(NORM_)?MAX' | \
   sed -e 's/\([^a-zA-Z0-9_]\)_timeval\([^a-zA-Z0-9_]\)/\1timeval\2/g' \
       -e 's/\([^a-zA-Z0-9_]\)_timespec_t\([^a-zA-Z0-9_]\)/\1timespec\2/g' \
       -e 's/\([^a-zA-Z0-9_]\)_timespec\([^a-zA-Z0-9_]\)/\1timespec\2/g' \
diff --git a/libgo/mksysinfo.sh b/libgo/mksysinfo.sh
index b32a0266b71..24d4ce2df6b 100755
--- a/libgo/mksysinfo.sh
+++ b/libgo/mksysinfo.sh
@@ -38,6 +38,7 @@ grep -v '^// ' gen-sysinfo.go | \
   grep -v '^type _*locale[_ ]' | \
   grep -v 'in6_addr' | \
   grep -v 'sockaddr_in6' | \
+  egrep -v '^const _*FLT(64|128)_(NORM_)?MAX' | \
   sed -e 's/\([^a-zA-Z0-9_]\)_timeval\([^a-zA-Z0-9_]\)/\1Timeval\2/g' \
       -e 's/\([^a-zA-Z0-9_]\)_timespec_t\([^a-zA-Z0-9_]\)/\1Timespec\2/g' \
       -e 's/\([^a-zA-Z0-9_]\)_timespec\([^a-zA-Z0-9_]\)/\1Timespec\2/g' \