Add --check option to scripts/baremetal.sh

Only effective together with --rom, makes two changes:
- abort in case of build warnings
- skip writing statistics

The goal is to make sure we build cleanly in the configuration used for
measuring code size, with all the compilers we use, both because we care about
that configuration and those compilers, and because any warnings would cast a
shadow on the code size measurements.

Currently the build fails with armc5 due to a pre-existing warning in PK, this
will be fixed in the next commit.

The next commit will also add an all.sh component to make sure we have no
regression in the future. (Which is the motivation for --check skipping
statistics: an all.sh component should probably not leave files around.)

While at it, fix two things:

1. The call to gcc --version was redundant with the echo line below
2. WARNING_CFLAGS shouldn't be overriden with armclang, as it would remove the
-Wall -Wextra and any directory-specific warning (such as
-Wdeclaration-after-statement in library). It's meant to be overriden only
with compilers that don't accept the default value (namely armc5 here).

scripts/baremetal.sh

@@ -75,15 +75,20 @@ baremetal_build_gcc()
     echo "Create 32-bit library-only baremetal build (GCC, config: $BAREMETAL_CONFIG)"
     gcc_ver=$($GCC_CC --version | head -n 1 | sed -n 's/^.*\([0-9]\.[0-9]\.[0-9]\).*$/\1/p')
 
-    CFLAGS_BAREMETAL="-Os -mthumb -mcpu=cortex-m0plus"
+    CFLAGS_BAREMETAL="-Os -mthumb -mcpu=cortex-m0plus --std=c99"
+    if [ $check -ne 0 ]; then
+        CFLAGS_BAREMETAL="$CFLAGS_BAREMETAL -Werror"
+    fi
     CFLAGS="$CFLAGS_BAREMETAL $CFLAGS_CONFIG"
 
-    $GCC_CC --version
-
     echo "GCC version: $gcc_ver"
     echo "Flags: $CFLAGS_BAREMETAL"
     make CC=$GCC_CC AR=$GCC_AR CFLAGS="$CFLAGS" lib -j > /dev/null
 
+    if [ $check -ne 0 ]; then
+        return
+    fi
+
     ROM_OUT_FILE="rom_files__${date}__${NAME}__gcc_${gcc_ver}"
     ROM_OUT_SYMS="rom_syms__${date}__${NAME}__gcc_${gcc_ver}"
     echo "Generate file statistics..."
@@ -108,10 +113,18 @@ baremetal_build_armc5()
     CFLAGS="$CFLAGS_BAREMETAL $CFLAGS_CONFIG"
     WARNING_CFLAGS="--strict --c99"
 
+    if [ $check -ne 0 ]; then
+        WARNING_CFLAGS="$WARNING_CFLAGS --diag_error=warning"
+    fi
+
     echo "ARMC5 version: $armc5_ver"
     echo "Flags: $WARNING_CFLAGS $CFLAGS_BAREMETAL"
     make WARNING_CFLAGS="$WARNING_CFLAGS" CC=$ARMC5_CC AR=$ARMC5_AR CFLAGS="$CFLAGS" lib -j > /dev/null
 
+    if [ $check -ne 0 ]; then
+        return
+    fi
+
     ROM_OUT_FILE="rom_files__${date}__${NAME}__armc5_${armc5_ver}"
     ROM_OUT_SYMS="rom_syms__${date}__${NAME}__armc5_${armc5_ver}"
     echo "Generate file statistics..."
@@ -132,13 +145,19 @@ baremetal_build_armc6()
     echo "Create 32-bit library-only baremetal build (ARMC6, Config: $BAREMETAL_CONFIG)"
     armc6_ver=$($ARMC6_CC --version | sed -n 's/.*ARM Compiler \([^ ]*\)$/\1/p')
 
-    CFLAGS_BAREMETAL="-Os --target=arm-arm-none-eabi -mthumb -mcpu=cortex-m0plus"
+    CFLAGS_BAREMETAL="-Os --target=arm-arm-none-eabi -mthumb -mcpu=cortex-m0plus -xc --std=c99"
+    if [ $check -ne 0 ]; then
+        CFLAGS_BAREMETAL="$CFLAGS_BAREMETAL -Werror"
+    fi
     CFLAGS="$CFLAGS_BAREMETAL $CFLAGS_CONFIG"
-    WARNING_CFLAGS="-xc -std=c99"
 
     echo "ARMC6 version: $armc6_ver"
-    echo "Flags: $WARNING_CFLAGS $CFLAGS_BAREMETAL"
-    make WARNING_CFLAGS="$WARNING_CFLAGS" CC=$ARMC6_CC AR=$ARMC6_AR CFLAGS="$CFLAGS" lib -j > /dev/null
+    echo "Flags: $CFLAGS_BAREMETAL"
+    make CC=$ARMC6_CC AR=$ARMC6_AR CFLAGS="$CFLAGS" lib -j > /dev/null
+
+    if [ $check -ne 0 ]; then
+        return
+    fi
 
     ROM_OUT_FILE="rom_files__${date}__${NAME}__armc6_${armc6_ver}"
     ROM_OUT_SYMS="rom_syms__${date}__${NAME}__armc6_${armc6_ver}"
@@ -284,7 +303,7 @@ baremetal_ram_stack() {
 }
 
 show_usage() {
-    echo "Usage: $0 [--rom [--gcc] [--armc5] [--armc6]|--ram [--stack] [--heap]]"
+    echo "Usage: $0 [--rom [--check] [--gcc] [--armc5] [--armc6]|--ram [--stack] [--heap]]"
 }
 
 test_build=0
@@ -297,6 +316,8 @@ build_armc6=0
 measure_heap=0
 measure_stack=0
 
+check=0
+
 while [ $# -gt 0 ]; do
     case "$1" in
         --gcc)   build_gcc=1;;
@@ -306,6 +327,7 @@ while [ $# -gt 0 ]; do
         --rom) raw_build=1;;
         --heap)  measure_heap=1;;
         --stack) measure_stack=1;;
+        --check) check=1;;
         -*)
             echo >&2 "Unknown option: $1"
             show_usage