lto/95190 - amend -flto docs for diagnostic option handling

This documents new GCC 10 behavior on diagnostic options and -flto.

2020-05-22  Richard Biener  <rguenther@suse.de>

	PR lto/95190
	* doc/invoke.texi (flto): Document behavior of diagnostic
	options.

(cherry picked from commit ab7eca92926fdc1da880120c116a1832fce56a29)

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 076b8f4c9063d5da6ff83c5f2e03c5a130b1568b..1e2f466b17d3ce4927e7819cbb67418aa36ff4c7 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2020-05-22  Richard Biener  <rguenther@suse.de>
+
+       PR lto/95190
+       * doc/invoke.texi (flto): Document behavior of diagnostic
+       options.
+
 2020-05-21  Uroš Bizjak  <ubizjak@gmail.com>
 
        PR target/95169

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index f98161391a0984c211a348acf36ae0bd03acc3a9..539d848f2f839e377c70398bc50f5f67da9e399b 100644 (file)
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -11204,6 +11204,14 @@ conflicting translation units.  Specifically
 precedence; and for example @option{-ffp-contract=off} takes precedence
 over @option{-ffp-contract=fast}.  You can override them at link time.
 
+Diagnostic options such as @option{-Wstringop-overflow} are passed
+through to the link stage and their setting matches that of the
+compile-step at function granularity.  Note that this matters only
+for diagnostics emitted during optimization.  Note that code
+transforms such as inlining can lead to warnings being enabled
+or disabled for regions if code not consistent with the setting
+at compile time.
+
 When you need to pass options to the assembler via @option{-Wa} or
 @option{-Xassembler} make sure to either compile such translation
 units with @option{-fno-lto} or consistently use the same assembler